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A License Plate Recognition and Speed Detection System

1. aif Fig 13 Speed Trailer Fig 14 Hand held Radar The purpose was to have these units act as a sensor to start the camera operation and trigger the license plate recognition software From our initial research we concluded that commercially available speed trailers and professional quality police radar units were far too expensive for this project Speed trailers cost around 5 000 and police radar units cost around 800 Since the ultimate goal of this pilot project was to combine speed detection license plate recognition and wireless mesh networks into a viable system we felt that the financial support we had could be better utilized in other areas 24 We briefly considered laser rangefinders but decided they were too dangerous and costly even if we could obtain ones that were used by law enforcement A special class of laser is required for police laser radar detectors which adds to their cost The laser rangefinders used for measuring distance on a golf course for example are not manufactured in a way that allows them to be pointed at people Thus they would be extremely dangerous if used to measure vehicle speeds We would also have the problem of measuring the speed of an object since these units are for distance only The traffic classifier units and traffic counters with road tubes while less expensive than the speed trailers and police radar units have the major drawback of needing to place a portion of the unit in the
2. Falcon e _ s a a mo o Ps o m m E AC Joe No No Yes TJ No iS a a ca DS ma Je es ves No rs Trooper Mw No Yes No sl A a a Elite Ka 1 SpeedTrak e e No Yes Yes Yes 94 LINE McCoy s LAW LINE MPH Industries MPH Industries MPH Industries MPH Industries MPH Industries MPH Industries MPH Industries MPH Industries Municipal Electronics Progressive Electronics Tribar Industries Tribar Industries Vindicator MANUFACTURER Elite K 1 SpeedTrak Elite KD Direction Sensing D E N ka h No Y o Fl a ht Series II Speedgun fel T e Yes ves No Yes BA Ge KT FO HB zas lel Te Ms e E Yes a Pe es a LA KGP Muni Quip pe a vai e ves a a Ore UNITS PREVIOUSLY APPROVED BUT NO LONGER IN PRODUCTION MODEL BAND S M MANUFACT MODEL BAND SM CMI Speedgun X M Kustom Signals KR 11 K M Magnum Decatur Electronics Hunter X M Kustom Signals Road Runner K S Decatur Electronics Hunter HHM X M Kustom Signals Trooper X M Decatur Electronics MVR 715 x M Kustom Signals PRO 1000 DS X M Decatur Electronics MVR 724 K M MPH Industries BEE 36 A X K M Decatur Electronics RA GUN GN X S MPH Industries K 15 X K S 1 Decatur Electronics RA GUN KN K S MPH Industries K 35 X K S 1 Federal Signals Enforcer K M MPH Industries S 80 X K M Kustom Signals HR 8 K S MPH Industries S 80 MC X K M Kustom Signals HAWK K M MPH Industr
3. 21 2008 00 791GP Sat May 03 13 50 21 2008 00 T J Sat May 03 13 51 40 2008 00 1f8 Sat May 03 13 51 40 2008 00 791FPB Sat May 03 13 51 40 2008 00 791GPB Sat May 03 13 51 40 2008 00 791GP Sat May 03 13 52 03 2008 00 791GPB Sat May 03 13 52 03 2008 00 791IPB Sat May 03 13 52 03 2008 00 I91IPB Sat May 03 13 52 04 2008 00 791 PB Sat May 03 13 52 04 2008 00 7911P8 Sat May 03 13 52 04 2008 00 791UP8 Sat May 03 13 52 04 2008 00 791FPB Sat May 03 13 52 04 2008 00 63 It should also be noted testing was done to make sure the application could communicate with the serial interface circuit board Even though the radar gun was malfunctioning we installed a dummy program on the serial interface board that continuously sent random 2 digit numbers I tested to make sure that these numbers were received displayed on the computer screen and recorded to a file along with the license plate number and time and date A picture taken during testing is shown below Fig 46 LPR exe application in action 64 VI Additional Applications The license plate recognition and speed detection system we have designed and implemented for this project can be further extended to other types of applications One such application would consist of a traffic display that would flash a driver s license number and warning message if the driver were speeding Similar systems exist today These speed display sign
4. Camera to vehicle distance 25 71 tan 6 Degrees 2 490 58 40 88 Camera Field of View Distance 2 x Y 2 x 25 71 50 42 12 64 14 Maximum Vehicle Travel Distance 39 51 2 14 12 64 Maximum Vehicle Travel Distance 6 69 When vehicle is in center of lane 96
5. Vehicles are imaged at a distance for three reasons One the camera angle as depicted in figure 9 should be kept at a minimum The larger the angle the more distorted the license plate characters will be due to 3D to 2D translation effects 14 Horizontal angle must not exceed 40 degrees Ref 33 Two the camera angle should also be kept at a minimum to prevent motion blur The larger the camera angle the quicker a vehicle will move across the camera s field of view causing a higher chance of motion blur And three a larger time frame window will be given for capturing an image of a passing car if it is imaged at a distance This will prevent vehicles from passing the camera without having their image taken It should be noted that the distance between vehicle and camera not be so great that minimal light from the license plate reaches the camera A balance must be achieved to obtain optimum picture quality Car Distance Video Camera Fig 9 Video camera orientation Telephoto lenses have three relevant specifications focal length horizontal field of view and aperture The focal length determines how much an image will be magnified The higher the value the higher the magnification A license plate under higher magnification will spread across more pixels in an image which in turn increases character recognition accuracy However this will decrease the horizontal field of view The horizontal field of view HFOV speci
6. across the image minimizing the number of pixels each license plate character spreads across It is desirable for a license plate character to cover a certain number of pixels in order to be accurately recognized For example if a camera s HFOV is 5 feet across and its horizontal image size is 640 pixels then the character 1 whose width is only 5 16 will be 3 pixels wide 5 16 5 12 640 pixels This may or may not be enough pixels depending on the object character recognition algorithms being used On the other hand having too many pixels can cause a negative effect The more pixels an image contains the longer it will take image processing routines to process the image A balance must be met It should also be noted that camera images should be clear and sharp with little noise Cameras that output digital signals such as DTV or computer protocol signals such as IEEE 1394 generally have better image quality than cameras that output analog signals such NTSC or PAL It is desirable for an LPR customized camera to output a clear sharp image to increase the accuracy of software image processing and character recognition routines Also depending on how the video camera is implemented it should either have a trigger port or a very high frame rate The trigger port is used to signal the camera when to take a picture The camera trigger port is connected to the trigger component of the LPR system that senses when a car is present If the
7. allocated Ka band 33 4 to 36 GHz for use with traffic control radars These units have a narrow beamwidth but they are also affected by weather conditions which shortens their operating range Manufacturers of Ka band radar have engineered their systems to provide channels either 12 100 MHz wide or 200 MHz wide Since the allocated operating frequency spans a 2600 MHz range a radar gun with a 100MHz channel width will have 26 different channels for its operation resulting in less interference with the system The last of the radar type systems is the LIDAR or LADAR The acronym stands for Llght Detection And Ranging or Laser Detection And Ranging and they were developed in the 1990 s They use Class 1 eye safe pulsed Infra red IR laser diodes at frequencies at the upper end of the IR spectrum and produce very narrow beams This is an important attribute when trying to measure vehicle speeds in congested areas These units are harder to operate compared to X and K band radar units They need to be pointed directly at the moving vehicle using a crosshair sight Thus the operating officer needs to be stationary when using a LIDAR whereas X and K band radars can be used in a moving police vehicle In either case the officer operating the radar unit must be trained and certified in their operation Photo radars figure 53 and Red Light Cameras figure 54 are two types of automated traffic enforcement devices that are used in
8. and converts it back to the decimal value of the vehicle s speed When the Ramsey kit was assembled we used IC sockets to mount the IC chips instead of soldering them directly to the printed circuit board This allowed us to solder the ribbon cable to the BCD counter chip without having to worry about damaging the chip or any other chip during assembly In testing the Radar Gun BasicStamp combination it was noticed that the digital readout on the Radar Gun went blank which meant we did not have an independent confirmation of the vehicle s speed The problem appeared to be caused by too large a drain at the BasicStamp connection To remedy the problem we first unsoldered the ribbon cable from the Readout s BCD output pins Then we purchased a second dual BCD decade counter and mounted it on the HomeWork module s breadboard Next the input signal was taken from the Readout s Quad NAND gate IC chip at pin 11 The second BCD counter was wired on the breadboard exactly as the one on the Readout s circuit board except it draws power directly from the lantern batteries and the second BCD s output pins were now connected to the HomeWork board s input pins 51 V B 4 Table of License Plate Recognition Speed Detection System Hardware Components Table 5 Our LPR SD Hardware Components Component Description Store Bought From Purchase Price Unibrain Fire I Board Color www unibrain com 10
9. appropriate driver Other than these specifications an LPR customized computer is much like any other desktop PC Table 3 LPR Computer Specifications Characteristic Desired Value Camera Interface Must match camera output or have PC card that can connect to camera Computer Case Weather proof Power Consumption Minimum power input Processing Power Comparable to high end desktop machine The more processors the better Wireless capability Needed if wired technology is unavailable Capture Card Driver Must be compatible with image processing software 111 D LPR Trigger The fourth component of an LPR system is a trigger License plate recognition systems need triggers to detect the presence of a vehicle and to signal the system to start capturing images of passing vehicles There are many different types of triggers An example of a trigger is MDL s LaserAce IM OEM Laser Modules specifications given in Appendix B MDL s LaserAce modules are laser range finders that detect the presence of a car using laser technology A trigger is composed of some type of sensor that senses the presence of a passing vehicle and outputs an electrical signal when a vehicle is detected This signal is sent to a camera s external trigger port The camera starts to capture images when this signal is received Most triggers are not 21 specifically sold fold for license plate recognition and must be customized to
10. by the Department of Public Safety The National Highway Safety Commission has set 65 55 mph as the speed limit on much of the Federal Interstate Highway system with lower limits set for densely populated areas It is the responsibility of the individual states to establish appropriate speed limits for roadways that are not part of the Interstate system For example Connecticut General Statute Title 14 Chapter 249 Part 1 Section 14 309 assigns the responsibility for determining safe speed limits to State Highway Traffic Commission In most states motor vehicle violations are considered warrant less misdemeanor violations and in general they fall under common law practice Ref 28 According to common 76 law a warrant less crime must be committed in presence of a police officer and the arrest for the crime must be immediate This has lead to a number of legal challenges to moving violation arrests based on the use of photo radars or red light cameras The challenges have two components First since the photo radar red light cameras are machines and not human beings the requirement in presence of a police officer was not met Second the infraction was recorded by a device that required the retrieval of film or the processing of digital data introducing a time delay the arrest was not immediate An on line review Lexus Nexus and Loislaw databases has shown the courts to be unsympathetic to these arguments provided that the citation
11. never take a doughnut break Christian Science Monitor 08827729 10 7 99 Vol 91 Issue 219 31 AN ACT CONCERNING ENFORCEMENT OF SPEEDING AND TRAFFIC CONTROL SIGNAL VIOLATIONS Connecticut General Assembly HB0574407563HRO January Session 2005 32 Author Hi Tech Solutions Date May 2 2004 License Plate Recognition A Tutorial Retrieved February 3 2008 from http www licenseplaterecognition com 33 Author Unknown Date Unknow EagleVision License Plate Camera Model Reg Retrieved February 9 2008 from http www eaglevision1 com LPR REG specs pdf 34 Author Lutchann Date April 17 2004 Choosing a Video Source Retrieved January 18 2008 from http www litech org spook whichcam html 35 Author Intel Corporation Date Unknown CXCORE Reference Manual 36 Author Intel Corporation Date Unknown CV Reference Manual 37 Author Intel Corporation Date 2001 Open Source Computer Vision Library 38 Author Unknown Date Unknown Welcome to OpenCV Wiki Retrieved January 21 2008 from http opencvlibrary sourceforge net 39 Author Remon Spekreijse Date A communication class for a serial port Retrieved March 17 2008 from http www codeguru com cpp in network serialcommunications article php c2483 40 Author Intel Date Unknown Intel Integrated Performance Primitives v5 3 Update 1 for Windows on IA 32 Intel Architecture Release Notes 41 Author Edmund Optics Date Unknow Electronic Imag
12. provide evenly distributed illumination from the foreground to background for the entire scene The shorter and thicker bulb filaments operating at lower voltages and temperatures are less vulnerable to shock and vibration The result of these features is a high performance illuminator with 40 higher efficiency and 50 longer life than traditional illuminators The U S Patented UF500 by Extreme CCTV is the favored illuminator in the UK where night time video monitoring is broadly utilized for proactive policing 91 Product Image Applications e Night time surveillance where normal lighting is too expensive or prohibited e Covert surveillance in a wide range of outdoor conditions Prison properties e School ground properties e Airport grounds where visible lighting is prohibited e Police surveillance to streets and buildings e Enhancement to motorized pan tilt zoom cameras for low light and backlight conditions Certifications Compliance CSA Std C222 No 0 M1991 CSA Std C22 2 No 0 4 M1982 CSA Std C22 2 No 66 1983 CSA Std C22 2 No 205 M1963 CSA Std C22 2 No 91 M91 CSA Std C22 2 No 250 00 UL Std No 506 UL Std No 50 UL Std No 1598 General Requirements Bonding amp Gmdg of Elec Equip Specialty Transformers Signal Equipment Special Purpose Enclosure Luminaires Transformers Specialty Enclosures for Elec Equip Luminaires EagleVision Reg L1 License Plate capture camera Extreme CCTV
13. real time traffic flow The map would be scroll and zoom capable showing the locations of LPR Speed systems When an LPR Speed system is clicked on a table is displayed listing vehicle information such as at what time vehicles passed and at what speed they were traveling Queries could also be run against the database such as Show the travel paths taken by a vehicle with license plate number FDE124 between 8 00 AM and 10 00 AM on December 8 2006 The map would highlight which LPR Speed systems the vehicle had passed and at what times This type of application could be helpful for many different types of scenarios Law enforcement could easily track a criminal s path in real time and be able to locate and capture them 70 VII State of the Art Commercial Systems One of the first traffic radar systems was built by Automatic Signal Company for the Connecticut State Police in 1947 These early radar units were based on heavy bulky vacuum tube technology and consisted of three parts a 45 lb box containing the transmitter receiver a strip chart recorder used to produce a permanent record and a calibrated analog meter to provide a reading in miles per hour Originally the transmitter receiver was mounted on a stand alone tripod or it was bolted to the hood of the patrol car It is interesting to compare this description with figure 52 which shows today s technology Fig 52 Modern Radar Gun 71 The hand held radar gu
14. roadway We felt that this would require special permission from the various regulatory agencies State Department of Transportation State Traffic Commission City of New Britain etc which may have taken a long time to be granted if at all Both the PIR motion detectors and the ultrasonic rangefinder while inexpensive have problems with the wide detection field and short effective distance The camera system we decided to use provides a quality image at distances from 50 to 500 feet depending on which camera lens is installed Although the PIR detector could cover the shorter end of this range it would respond to any motion within a 60 degree field of view The ultrasonic detector suffered from an extremely short usable range which did not exceed 10 feet This leaves us with the microwave radar units of which we found two very inexpensive types Mattel Toys makes one for their Hot Wheels 1 64 in scale cars fig 15 and the other one is a kit made by Ramsey Electronics fig 16 25 Fig 15 Hot Wheels Radar Gun Fig 16 Ramsey Electronics Radar Kit Since the Mattel Radar Gun was the least expensive we purchased that one first Both of these units operate in the microwave range of frequencies The Mattel unit at 10 525 Gigahertz GHz is an X band radar unit the Ramsey kit at 2 6 GHz is in the now obsolete S band Ref 10 Both units determine the speed of an object based on the Doppler Effect 26 The Doppler Effect f
15. the pointing al direction We expect the beam width to be in the range of 15 to 20 degrees although we haven t measured it The oscillating electromagnetic wave induces an alternating current in the antenna wire This current forms the signal we are trying to detect The signal is passed to a Schottky diode a k a hot carrier diode These diodes have low junction capacitance low junction voltage and fast switching speeds making them ideal for the detection of low voltage high frequency signals The signal then passes through a low pass filter circuit This circuit is formed by the R3 lkohm resister and the surface mounted 0 001 micro Farad capacitor C7 A low pass filter is used when we are interested in frequencies below a specified cutoff level The following equation is used to calculate the cutoff frequency Fc 1 DER EC Where Fc the cutoff frequency m 3 1415 R resistance in Ohms C capacitance in Farads For this section of the circuit the cutoff frequency is 159 2 kHz The Ramsey user s manual states the correct Doppler shift at the operating frequency is 7 76 Hz per mile an hour Ref 1 Since the readout provides for a two digit display we can measure speeds up to 99 mph This gives a Doppler shift of approximately 770 Hz The filtered signal now passes to the base of a NPN 2N3904 transistor that is configured as a common emitter amplifier The 2N3904 is a general purpose transistor that can amplif
16. various parts of the United States Fig 53 Photo Radar Fig 54 Red Light Camera The FDA Center for Devices and Radiological Health regulates the manufacture and sale of laser devices in the United States Class1 lasers are defined by the American National Standards Institute 73 Early in their development stages these devices used wet film cameras to record alleged violators actions This required a police officer to manually retrieve the film have it developed and then it required visual inspection to obtain a license plate number When Charge Coupled Device CCD cameras became available in digital cameras they replaced the film camera The pictures could now be recorded on flash drives saving the time and expense of developing film However an officer still had to retrieve the flash drive With the proliferation of wireless communications devices it should only be a matter of time before a company like Hi Tech Solutions replaces the wired connections in the diagram below with wireless connections via Bluetooth or ZigBee technology For a listing of major radar gun manufacturers please see Appendix A Typical SeeLane Configuration Database Fig 55 Possible Traffic Enforcement Network 74 As with any new technology affecting people s lives automated traffic enforcement systems have been the object of various legal challenges which we ll briefly discuss in the next section Legality of LPR traffic vio
17. 06 VIER Concha siO Nendor IX References gives oi cv n n r doi Appendix A Our LPR SD System Component Specifications Appendix B Commercial Components scsecssssseeeeee Appendix C Camera Setup Calculations ccsceseeeees I Abstract Since the 1980 s law enforcement has deployed traffic enforcement camera systems to monitor roadways for traffic violations There are a variety of commercially available systems today that can capture images of vehicles running red lights passing toll booths without paying speeding or traveling on restricted lanes In many cases the LPR unit is added as retrofit in addition to existing solutions such as a magnetic card reader or ticket dispenser reader in order to add more functionality to the existing facility Ref 32 Basic systems capture images of passing vehicles and require human intervention to decipher license plate numbers A person will have to analyze the picture containing the traffic violation decipher the license plate number of the violating vehicle and generate the fine for the violation More advanced systems use image processing techniques to extract license plate numbers from camera images This allows traffic fines to be automatically generated and sent to the appropriate violator without the need for human intervention These types of systems are called license plate recognition LPR systems or automatic number plate recognition ANPR syste
18. 2 44PM 3 30PM Weather Sunny Light Source Used Sun Camera to vehicle distance 38 feet Speeds Tested mph 5 10 30 40 62 Plate Number 791GPB Test Results The license plate was detected at all speeds Most of the tests resulted in 4 to 6 license plate characters being detected correctly Recorded Results 91GPB Sun Apr 20 14 44 10 2008 00 Actual plate 791GPB 791GPB Sun Apr 20 14 44 10 2008 00 791GPB Sun Apr 20 14 44 10 2008 00 791GPB Sun Apr 20 14 44 10 2008 00 791GPB Sun Apr 20 14 44 11 2008 00 791GP8 Sun Apr 20 14 44 11 2008 00 791GPB Sun Apr 20 14 44 11 2008 00 791GPB Sun Apr 20 14 44 11 2008 00 791GPB Sun Apr 20 14 44 11 2008 00 791GPB Sun Apr 20 14 44 11 2008 00 791GP Sun Apr 20 14 44 11 2008 00 716PB Sun Apr 20 14 49 36 2008 00 7916P Sun Apr 20 14 57 53 2008 00 7916P1 Sun Apr 20 15 02 16 2008 00 Day 3 May 3 2008 1 30PM 2 15PM Weather Overcast Light Source Used Artificial lighting from a set of vehicle fog lights Camera to vehicle distance 40 feet Speeds Tested mph 5 10 25 30 Plate Number 791GPB Test Results The license was detected at all speeds Most of the tests resulted in 4 to 6 license plate characters being detected correctly Recorded Results 791GPB Sat May 03 13 50 21 2008 00 791GPB Sat May 03 13 50 21 2008 00 791GPB Sat May 03 13 50 21 2008 00 791GPB Sat May 03 13 50
19. 3 The source code on the microprocessor was locked 4 The locks could be removed only by erasing the entire code 5 Even though the ATmega88 has UART pins we doubted the code was written to address them 6 A search of the Internet revealed only one partial circuit diagram which was of little help 29 7 The source codes and circuit diagrams are proprietary property of Mattel Toys and they would not release them even for a discontinued toy Given these drawbacks the only part of the Mattel Speed Gun that might prove useful would be the detector tube with it s transmit and receive antennas all other supporting circuitry would have to be designed from scratch We felt we had another alternative in the Ramsey Electronics SG7 kit which will be described later 30 V Our System Design and Implementation V A Overview The system designed and implemented for this project is called the license plate recognition speed detection LPR SD system The system receives two inputs One input consists of live video taken of passing vehicles traveling down a throughway The second input is the speed of passing cars obtained from a radar gun The LPR SD system processes these inputs and outputs a computer file The file contains information on passing cars including their license plate number the speed they were traveling and the time and date they passed Computer file _ Containing vehicle Gi information License Plate k
20. 5 Video Camera 12V AC adapter www unibrain com 20 Unibrain FirWire 400 CardBus www unibrain com 45 Card Unibrain 50mm Telephoto Lens www unibrain com 70 Ramsey Electronics SG7 kit www ramseyelectronics com 70 Radar Kit Basic Stamp Training Kit www parallax com 80 Serial Interface Circuit Board Compaq nc6220 Laptop www hp com pj Computer TOTAL 390 Note We did not include the cost of the laptop computer V C LPR Software There are software packages available for license plate recognition An example is HI TECH Solutions SeeCar Software Recognition Package pricelist given in Appendix B However these software packages cost over 4 000 per license which was beyond our budget limits Instead we wrote our own software to perform the license plate recognition We researched free available software libraries to minimize the amount of customized code that would need to be written Customized code was written to glue these libraries together and provide any additional functionality The libraries and customized code were combined in to one application executable called LPR exe The executable runs on Microsoft Windows XP The following screen shots show the menus and windows of the application 52 Application Main Window 8 License Plate Recognition Camera Mode Rate LPR Help Displaying 29 2 fps 2 2 dropped Fig 37 LPR exe application main window The picture above shows the main window of t
21. A License Plate Recognition and Speed Detection System Leo Cetinski David Dawson A Special Project Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science In Computer Information Technology Department of Computer Science Management Information Systems and Industrial Technology Central Connecticut State University New Britain CT 4 2008 Thesis Advisor Dr Farid Farahmand Contents I ADSI ACE evursase vis sode v d ioten eaea II IN POMUCNON 5 akide HI License Plate Recognition Concepts seeee A LPR Light SOUFCE 0 0 oe c vesvese vese ece vese eve cen onevesese B EPR Camera nsien c s ri t C LPRGomputer viosn k si s Ds EPR IrIOOON stanit detet end dd e e des IV Speed Detection Radar Concepts ccscceecesees V Our System Design and Implementation Ar OVERVIOW es aa on dans na dar kd B Components dei dd eens 1 LPR Component cessssscsssesseees 2 Radar Guda 3 Serial Interface Circuit Board 4 Table of System Components C LPR SOMWaAres fia case DO cee irois 1 Instructions for Running the Software 2 Software Architecture cccceeeeeeoes 3 Application Layer Algorithms D T SHNO oinakion inc onndsh sesi d non VI Additional Applications anale uec on ee eee ee eee e once once VII State of the Art Commercial Systems 0
22. Key G e Extreme s proprietary DHC Imaging technology for definitive high contrast license plate capture e Precision engineered optics captures plates from vehicles moving up to 100mph 160kph for high speed applications e Metaphase LEDs deliver powerful infrared illumination for effective license plate capture up to 75ft 23m e Advanced ambient rejection technology solves problems related to glare from sunlight headlights and high beams e 00TVL 1 2 LXR CCD for excellent performance under infrared e 24 7 license plate capture in day or dark conditions e Energy efficient operation at 12VDC or 24VAC e Small compact housing with covert installer friendly design e Suitable for outdoor use in all weather conditions e Long life LEDs save time and money by eliminating bulb changes e High contrasi DHC Imaging allows optimal DYR integration or Automatic License Plate Recognition ALPR performance e DHC lmaging technology delivers images of both conventional plates and Digital License Plates DLPs Product Description REG L1 featuring DHC Imaging delivers advanced performance license plate capture for technical surveillance and represents the third generation of license plate capture solutions from Extreme CCTV Combining Extreme s latest propnetary technology DHC Imaging integrates advances in optics infrared illumination and Ambient Rejection technology to produce high contrast license plate image
23. R SD System Process Flow Retrieve picture of throughway NO Does licensd plate exist in image Get vehicle speed Detect license plate characters Record time vehicle speed and vehicle license plate numbers Fig 23 LPR SD system process flow 33 V B License Plate Recognition Speed Detection System Components V B 1 LPR Components The license plate recognition part of our system includes the light source video camera and computer components Our budget limited us to the most basic appliances We used a vehicle s headlights for a light source a FireWire webcam for a video camera and a laptop for a computer We also tried using just sun light for a light source Pictures of our system setup are given below The system was setup two different ways One way was to position the system in front of a vehicle and use the vehicle s headlights for a light source This is shown in figure 24 Another way our system was setup was to position the system on top of a small desk and use only the sun as a light source as shown in figure 25 5 3 2006 Fig 24 Image of our LPR SD system in front of a vehicle 34 Fig 25 Image of our LPR SD system positioned on desk using sun as light source One major difference between our system and a commercial license plate recognition system is our use of visible light to illuminate the license plate Most LPR systems use near infrared light It should be noted that both t
24. adable image picture or leave on auto settings 7 Click Rate gt 30fps Sets camera to send images at 30 frames per second 8 Click LPR gt Set Threshold plate number Enter the license plate number of the vehicle in focus 9 Click LPR gt Set Intensity Threshold This will set the intensity threshold 10 A popup window will show the chosen intensity threshold Make sure this number is not 0 and click OK ee Ov Once the threshold is set the application can start recording license plates of passing vehicles Click LPR gt Start Recording to record license plate numbers to a file named licensePlates txt 55 V C 2 Software Architecture To create the application we researched available software libraries that were within our budget limits We then created customized C C code to glue these libraries together as well as add any additional functionality We used Microsoft Visual C to compile and link the application A diagram of the software layer architecture is given below Fig 41 Application software layer architecture The LPR application layer contains the customized code we created for the application It calls functions contained in the lower layer libraries The Microsoft MFC library was used to help create the user interface It contains C classes for creating application windows and menus This library is not free and comes with certain versions of the Microsoft Visual Studio package The Intel OpenCV Open Com
25. age processing object character recognition video camera communication and serial port communication Learn how to use those libraries 9 Create customized software code to call those libraries and perform the necessary functions required by the application 10 Perform tests to measure the quality of the system Bl On Po a This document coincides with the system we have built for our capstone project It first describes license plate recognition LPR and radar technologies in general It then outlines the system we designed and implemented for our application along with its limitations and the test cases we ran against the system This document then goes on to describe how our application could be extended for other types of applications It also discusses available commercial systems that detect traffic violations and their legality III License Plate Recognition Concepts License plate recognition LPR is becoming an established technology Its development over the past two decades has given rise to highly accurate systems Whole systems can now be purchased for specific applications ranging from private parking access to traffic light violation detection Different applications require different systems An LPR system can be located on the side of or above a roadway at a toll booth or at another type of entrance way All LPR systems follow a basic high level process The process starts when a sensor detects the presence of a vehic
26. appendix C Our LPR system used a standard laptop Compaq nc6220 to run the image processing and object character recognition software The processing power of the laptop was fast enough to detect the presence of a vehicle in an image within the 30 frames per second time limit It was also fast enough to perform the character recognition before a second vehicle would pass We also purchased a FireWire PCMCIA card for the laptop to be able to connect the video camera to the laptop since it did not have a FireWire port Using a laptop is impractical for an LPR system Most systems need to be weatherproofed 38 V B 2 Radar Gun The Ramsey Kit Ramsey Electronics of Victor New York Ref 3 has been selling hobby electronic kits since the early 1970 s The advantages of using the Ramsey kit over hacking the Mattel toy is that the kit has a full schematic diagram and all parts are labeled Thus it is easier to locate the point in the Ramsey circuit where we could tap into the circuit for an RS232 fed line We purchased and assembled a kit similar to the one shown below Fig 29 Ramsey Radar Gun Kit The Microwave Oscillator Circuitry The kit contains two printed circuit boards that require assembly the microwave oscillator board and the speed readout board We will discuss each in turn Figure 30 is the circuit diagram for the microwave oscillator Figure 31 shows the completed circuit board 39 Please note for reader convenie
27. be incorporated in to the LPR system Other types of triggers include pressure sensors infrared sensors magnetic field detector sensors and video cameras Pressure sensors consist of tubes or wires that are laid across the roadway When a vehicle rolls over the tube or wire the pressure in the tube rises or the resistance in the wire changes causing the sensor to output an electrical pulse Infrared sensors use infrared light to detect the presence of a vehicle It is similar to the sensors located on an automatic garage door opener that prevent the door from closing when an object is located under the door The infrared sensor consists of an emitter and receiver The emitter sends infrared light to the receiver If the receiver does not receive the infrared light it sends an electrical pulse signaling an object is in its path A magnetic field detector sensor detects the presence of vehicle by the vehicle s magnetic field All vehicles have a magnetic field due to the large amount of metal used by them Video cameras can also act as triggers They can continually monitor the street and use image processing techniques to detect the presence of a moving object For traffic violation type applications laser range finders are mostly used to trigger the camera There are certain specifications that are desirable for an LPR customized trigger It is desirable to have a sensor that is unobtrusive as possible If tubes or wires cannot be laid across the r
28. be sending speed and license plate information to the traffic sign The data size would consist of a few bytes for each car ZigBee wireless technology would match the performance and range needed Digiboard s ZigBee modules such as the XBee PRO Znet 2 5 OEM RF Module would work well These modules connect to the serial port of a computer and provide 250kpbs bandwidth at up to one mile away There are many different traffic display signs available We would only need one which could be programmed through a serial or USB port It would not need speed radar capability since our LPR system would already be sending speed information A computer would be 66 needed to communicate with the traffic display and also to receive the wireless signals being sent by the LPR system A Via mini ITX computer would be a good match for the requirements needed Customized software would also need to be created Overall the system would be very similar to the system we developed for this project However instead of recording license plate and speed information to a file they would be sent wirelessly to the remote computer connected to the traffic display sign Another type of application our system could be extended to is a wireless network of LPR Speed detection systems connected together in a hierarchical star topology The network would span across a city or town and be monitored by the local law enforcement Each LPR Speed system would record speeds and license p
29. by the user Set threshold value to 0 Compare license plate characters detected in image to those input by the user Record how many characters match Increment threshold value Go to step 3 until threshold reaches 255 When the previous steps are complete an array will be created such as the one shown below Threshold 147 148 149 150 151 152 153 154 155 Matches 5 6 5 6 5 6 6 6 5 8 Fig 45 Array of correct character matches made for a particular threshold value The array contains how many character matches were made for each threshold 59 9 The algorithm then finds the longest run of maxes and finds their median This median is the optimal intensity threshold I E intensity threshold 152 154 2 153 intensity threshold is an integer This completes the description of the application developed for this project By using existing free or relatively free software libraries and creating our own customized code we were able to build an executable that could recognize and record the license plate numbers of passing vehicles V D Testing Testing was done throughout the build of the system Tests were run against each individual component to ensure its functionality Three separate components the radar gun the serial interface circuit board and the license plate recognition software were each tested separately A full system test was never accomplished due to a malfunction
30. ce should be physically located near the video camera License plates are coated with reflective paint When a light source shines on an object coated with reflective paint the light rays are reflected back to the light source origin This effect causes the license plate to be significantly illuminated compared to other objects in the picture An example of this effect is shown in the figures below Fig 2 Camera located near light source Fig 3 Camera located away from light source Ve test Light Rays Tay te te te e Light Source eer Video Video Camera Gy Camera iB Fig 4 Camera located near light source Fig 5 Camera located away from light source The picture in figure 2 was taken with a light source and camera located near each other The light rays striking the license plate in figure 2 are depicted in figure 4 In figure 2 light rays striking the license plate are mostly reflected back to the light source where the camera is also located This is what causes the license plate to be more illuminated than the rest of the objects in the picture The picture in figure 3 was taken with a light source and camera that were separated by an angle of 45 degrees Light rays striking the license plate in figure 3 are depicted in figure 5 Again most light rays reflecting off of the vehicle license plate are reflected back to the light source However in this case since the video camera is no longer near the light so
31. ce them into a hierarchical tree 060000090 Fig 44 Mapping image contours in to a tree structure 58 W1 B2 B3 B4 W5 Bo B7 B8 B9 B10 and B11 are all contours W1 is the top node in the tree It contains all other contours B2 contains contour W5 W5 contain all the license plate character contours Traverse down the tree and locate any nodes that have 3 to 6 children that are all of a certain size and are positioned at the same height These contours are most likely license plate characters Therefore a license plate has been detected Once a license plate is detected the contours are passed on to the character recognition functions These functions convert the images to text Another algorithm coded at the application layer automatically calculates the most optimal threshold value The intensity threshold value is used by image processing functions to determine which pixels are changed to white and which are changed to black The algorithm to set this intensity threshold value is simple The user enters a license plate number that is currently being viewed by the camera The software then tries a range of threshold values to determine which threshold value provides the closest match to the license plate entered by the user This threshold value is then used for all subsequent license plate detections The algorithm steps are given below SHQYEN e GP p Receive the correct license plate characters input
32. cessed 5 06 2007 3 Ramsey Kit http www ramseyelectronics com Accessed 4 24 2008 4 Hot Wheels Internal view http www edparadis com radar Accessed 3 17 2008 5 Layered Circuit Board http www edparadis com radar Accessed 3 17 2008 6 Ramsey Microwave Oscillator PCB www rcgroups com forums showthread php t 205460 7 Ramsey Readout PCB www rcgroups com forums showthread php t 205460 8 HomeWork Board http www parallax com 9 Modern radar unit www answers com topic radar gun 10 Photo Radar http www CopRadar com 11 Red Light Camera http en wikipedia org wiki Road rule_enforcement_camera 12 Microwave Oscillator Circuit Diagram Speedy Personal Speed Radar Kit Ramsey Electronics Model No SG7 13 Readout Circuit Diagram Speedy Personal Speed Radar Kit Ramsey Electronics Model No SG 7 14 Doppler Effect http www glenbrook k12 il us GBSSCI PHY S CLASS waves u1013d html 82 15 Radar Setup http mpdc dc gov mpdc cwp view a 1240 g 548005 mpdcNav_GID 1552 mpdcNav 7C31886 7C asp 16 License Plate Recognition A Tutorial http www licenseplaterecognition com 17 Doppler Radar http en wikipedia org wiki Doppler_radar 18 Collura J and Heaslip K Next Generation Automated Enforcement Automated Speed Enforcement and Variable Speed Limit Signs Combined to Make Roadways Safer Philip E Rollhaus Jr Roadway Safety Essay Contest 2005 19 Managing Speed Review of C
33. d Once the PIC is programmed it will continue to run its program ad infinitum To stop the program just unplug the battery to start it again just plug the battery back in The program we used to acquire data from the Ramsey Radar Gun is shown below Speed Gun Sensor Uses a Ramsey Electronics SG7 Personal Radar Speed Gun kit as a speed sensor 8STAMP BS2 YSPBASIC 2 5 Main INPUT 15 Sets pins as input pins INPUT 14 INPUT 13 INPUT 12 INPUT 11 INPUT 10 INPUT 9 INPUT 8 PAUSE 200 Pauses program for 200 milliseconds DEBUG BINI IN15 BINI IN14 BINI IN13 BINI IN12 BINI IN11 BINI INIO BINI IN9 BINI IN8 CR Reads the value on each pin and sends it to the laptop GOTO Main Loops endlessly END The Speed Gun Sensor program runs a BasicStamp2 module STAMP BS2 using the PBasic v 2 5 programming language PBASIC 2 5 In the Main section of the program 50 we Set pins 8 to 15 as input pins and pause the program for 200 milliseconds This pause time was chosen because it is somewhat longer than the cycling time of the BCD counter which requires 143 milliseconds to update itself After pausing the DEBUG routine sends the value on each input pin out the serial port to the laptop via an RS232 connection The value on pin 15 represents the most significant bit and the value on pin 8 represents the least significant bit in the Binary Coded Decimal The laptop computer takes this binary input
34. d the high frame rate in order to capture images of passing vehicles before they drove out of the camera s view The camera output images in digital format at 640x480 pixels Therefore pictures were clean with little noise and the high resolution provided the needed detail to recognize license plate characters A 50 mm focal length lens was mounted on the camera providing the magnification needed to image vehicles at a distance One major advantage of using this camera was that it used the IDC DCAM Instrumentation amp Industrial Digital Camera protocol Most FireWire webcams available are compliant with the IIDC specification This means that no device specific driver is necessary to interface with the camera Ref 34 I was able to find a free software library for this protocol and used it to communicate with the webcam One major disadvantage of using this camera was the long exposure time needed to capture images using a telephoto lens The long exposure time limited the speed vehicles could travel without causing any blur 36 Our video camera served two functions One it had to capture high quality images of passing license plates for the recognition software to extract and recognize license plate characters and two it was used as a trigger to detect the presence of a license plate in an image We had to make sure the camera was capable of performing both functions We also needed to know how to setup the camera to perform both functi
35. e 2 DDR2 533 667 SDRAM sockets Up to 3 2568 memory size Built in Intel Graphics with GMA X3100 Technology 1 PCI Express 16 1 PCI 32 bit 1 PCI Express Mini Card 1 ATA 100 40 pin 2 SATA 3Gb sec connectors 8 USB 2 0 1 Intel 82566DC 10110071 000 1 Intel 82573L 1010071000 ALC888 7 1 5 1 channel HD audio codec 1 PS2 mouse port 1 PS2 keyboard port 1 VGA port 1 RS 232 COM port 2 LAN ports 4 USB 2 0 ports 6 Audio jacks line out line in mic in rear surround out center subwoofer out S PDIF out optical 1 IDE slot 1 L YDS connector 1 DIO connector 16 GPIO 1 RS 232 COM connector 1 Parallel port connector 1 SIPDIF connector 2 SATA connectors 1 TV out connector 2 USB 2 0 connectors for 4 USB ports 1 Front panel connector 1 Amplifier connector 4 pin 2 Fan connectors ATX power connector 88 MDL LaserAce IM OEM Laser Modules LaserAce IM Overview Product number 9001 Make an Enquiry OEM Laser Module More Information The LaserA4ce IM OEM Laser Modules are compact class 1 eye safe rugged multipurpose laser distance meters for integration into OEM applications The laser distance measuring modules have been specifically designed for additional integration each giving a reflectorless range of up to 700m 2300ft 300m 1000ft 150m 500ft and 35m 110ft for the IM700 IM300 IM150 and IM35 respectively The sensors can be integrated into a number of suitable system applica
36. e Center and the tightened airport security that 47 resulted we felt it would be asking for trouble to follow this suggestion Thus we decided to accept the limitation of a two digit display We came across some Blogs on the web during the course of our investigations concerning the size of an object that can be detected by the radar gun To detect an object its physical size must be equal to or greater than the wavelength of the impinging radiation The Ramsey radar gun operates at a frequency of 2 6 GHz So an object larger than the corresponding wavelength will be detected while smaller objects will go unseen Use the following formula to calculate the wavelength A corresponding to a frequency of 2 6 GHz N c f where A wavelength c speed of light 186 000 miles per second f frequency in Hertz Hz Thus A 186 000 miles second 2 600 000 000 cycles second 0 00007154 miles x 5280 ft mile 0 3777 ft x 12 in ft 4 53 in At a frequency of 2 6 GHz the smallest object that can be detected is 4 53 inches in diameter 48 V B 3 Serial Interface Circuit Board The optical character recognition system stores the processed images on a laptop computer We wanted to store the speed data from the Ramsey Radar Gun on the same computer The Radar Gun kit was not designed to provide a computer interface so we decided to solder an eight wire ribbon cable to the output pins of the dual BCD decade counter IC chip The ribbon cab
37. e light into electrical energy The CCD chip sensors must be extremely sensitive to near infrared light This is to offset the minimum amount of light energy that will fall on the CCD as previously discussed Sensitivity is usually defined in a camera specification called the minimum illumination It is measured in LUX The lower the LUX value the more sensitive the camera is to light A very low LUX value is desirable for license plate recognition Consumer cameras are built to be sensitive to mostly visible light An LPR camera needs to be sensitive to near infrared light The graphs below show the difference in sensitivity between a standard consumer CCD chip and one specialized for infrared imaging 17 Sensitivity 100 80 60 40 20 400 500 600 700 800 900 1000 Wavelength nm Fig 11 Sensitivity for standard consumer CCD Ref 43 Sensitivity 100 80 60 40 20 400 500 600 700 800 900 1000 Wavelength nm Fig 12 Sensitivity for LPR CCD An LPR CCD is much more sensitive than a standard consumer CCD chip at the near infrared wavelengths of light gt 700nm Such sensitivity is necessary to capture detailed images of high speed moving objects at a distance with near infrared illumination Another CCD specification is the large number of image pixels needed to accurately recognize license plate characters If the camera s field of view covers most of the lane s width the license plate will extend only a small portion
38. e plate recognition is similar to a standard PC running a Windows or Linux operating system An example of a good candidate computer would consist of an MSI Industrial GM965 Mini ITX motherboard running an Intel Core 2 Duo Mobile processor see appendix B There are several characteristics an LPR customized computer should have A powerful microprocessor and much memory are needed to perform the demanding calculations needed by the image processing and object character recognition algorithms Having multiple processors is a plus due to the parallel nature of these algorithms For example one processor can run low level image processing functions while another processor performs object character recognition functions For roadside LPR systems it is desirable to have computers that are compact weather proof and consume minimum electricity They may need to have wireless communication if wired technology is unavailable The LPR computer may also need to have an image acquisition capture card in order to connect to a camera The type of card is dependent on the camera interface If camera output is an analog 20 signal such as NTSC a capture card with composite input is needed If the camera output is a computer standard such as the IEEE1394 protocol a FireWire card may be necessary It is important to note that different types of cards require different software drivers and the license plate recognition software must be able to communicate with the
39. e stays within its lane its license plate will be illuminated when it passes A summary of desirable LPR light source characteristics is given in the table below When a light source contains these characteristics the intended license plate will be properly illuminated Table 1 LPR Light Source Characteristics Characteristic Desired Value Physical Location As close as possible to camera aperture Wavelength of light Near infrared 12 Uniform and Constant To be as uniform and constant as Intensity possible Power of intensity To provide enough lighting so that image detail meets image processing requirements Projection Beam Angle To cover entire width of street lane 111 B LPR Camera The second component of a license plate recognition system is the video camera The video camera captures images of passing vehicles and transfers those images to the computer An industrial or computer vision grade video camera provides the characteristics required by LPR systems A good example is the LXR CX800 specifications are given in Appendix B A video camera for license plate recognition has three components a long pass filter a telephoto lens and a CCD chip A description of these components and their characteristics is provided in the following paragraphs License Plate Image Digital re JA Constitution State Signal i Output I CONNECTICUT I I CCD Teleph
40. ehicle was traveling The license plate number shown in this window is not an image but text The three application windows show how the software converts live video to license plate number data 54 Object 4 Image Character Processing Recognition License Number Functions Functions 791GPB Speed 00 Fig 40 LPR exe application windows showing image progression V C 1 Instructions for Running the Application The application is run by double clicking the LPR exe icon on the desktop Before the application can successfully record license plate numbers of passing vehicles the intensity threshold must first be set The intensity threshold is a value used by the image processing algorithms and will be described in more detail later To set the intensity threshold the video camera should be placed in its final position along the roadside The camera should be focused on a vehicle license plate The vehicle should be in the center of its lane approximately 38 5 from the camera lens Click Camera gt check link This will search the laptop for attached cameras Click Camera gt select camera This will select the desired camera Click Camera gt init camera This will initialize the camera Click Mode gt 640x480 Mono 8 bit Camera images will be 640x480 pixels each pixel will have an 8 bit value Click Camera gt Show Camera Click Camera gt Control Dialog Optional Set appropriate camera settings for a clear re
41. ense plate number for each passing vehicle is recorded in a computer file We researched available technology and currently available systems and components to build our system with We found commercial systems available for license plate recognition but for the most part did not include the calculation of the speed of the vehicle We researched how feasible it would be to convert a currently available LPR system to also include the speed of the vehicle We found that commercial systems were well beyond our budget limits costing over 8 000 We also found most systems to be closed systems They did not provide the open interfaces needed to configure them for our project s application Instead of using a commercial system the LPR component of our system was built from scratch We also found commercially available radar guns capable of detecting a vehicle s speed and able to connect directly to a computer Again we found that these radar guns were well beyond our budget limits costing 1 000 or more If we had more resources our project would have been much simpler We could have simply used a Stalker Radar Speed Sensor www stalkerradar com along with HI TECH Solutions SeeRoad LPR system www htsol com Since most commercially available products were out of our reach we had to build our system mostly from scratch We used available components to build our own LPR system and used two electronics kits to build the radar gun We designed a s
42. fered by Zigbee would be large enough even to handle the increased bandwidth needs at nodes closer to the police station This is due to the small data size of the information being transferred across the network If there were a need to have LPR systems further distant from the police station such a system could be implemented using cell phone technology such as CDMA or GSM The network architecture could have a hierarchical star topology such as the one shown below 68 ucts NG F N E uA and i s wk a kta vi v awe P A I oc 4 AO ata NJi f n Fig 50 LPR application of networked LPR SD systems in a hierarchical star shaped network At the police station the central database would record all traffic information received from the remote LPR Speed systems An application would run on top of the database that could display this information on to a dispatcher s computer screen A map would display where a vehicle had passed as well as at what time the vehicle had passed and the speed they were traveling An example is shown below 69 YAHOO gt gt Gh Ave ie LPR 44 1h fd 44Dr 11St ees E ZA ty R t 1 License Time Date Speed 4 Pe 894245 8 30A 8 9 07 54 ke s 1 429054 8 28A 8 9 07 56 as 342456 8 26A 8 9 07 54 i g 1 384956 8 26A 8 9 07 51 I 245689 8 25A 8 9 07 45 De Se a a i ox 2 R 45th Ay 100m 250 ft Yahoo 2008 Data NAVTEQ2008 Fig 51 Example of an LPR application window showing
43. fication defines how much of a view is captured in a picture The HFOV specification is given as an angle and is depicted in the diagram below The HFOV should be wide enough to capture an image of a license plate of a passing vehicle that is traveling within its lane For example if a 15 lane is 9 feet wide the HFOV should be at least 5 feet wide in order to capture the license plate of a passing vehicle even when the vehicle is traveling within its lane Viaeo Camera NE Fig 10 Camera horizontal field of view Another telephoto lens specification is the aperture The telephoto lens aperture defines the size of the hole that allows light to pass through The larger the value the more light enters the camera providing faster exposure times Hovvever too large a value vvill provide a smaller depth of field and the image will be in focus for only a small range The depth of field DOF of a lens is its ability to maintain a desired amount of image quality as the object is positioned closer to and further from best focus Ref 41 A telephoto lens that meets LPR requirements will have a depth of field capable of imaging cars at varying distances and also allow enough light to enter for fast exposure times 16 The video camera has another component called the charge coupled device CCD chip Light passes through the telephoto lens and lands on the video camera s CCD The CCD converts electromagnetic energy received from th
44. hase of a SeeCar SRP Price 4 250 per license discounts apply to volume orders as per table below Applicable Countries Worldwide specific country list available upon request Payment Terms Prepayment upon placement of order Quantity Discount Schedule Pin ty Max Gty Discount Price S 93 Commercial Radar Gun Specifications Speed Measuring Device Police Radar CONSUMER PRODUCT LIST CPL January 2003 UNITS CURRENTLY IN PRODUCTION S Stationary M Moving MANUFACTURER MODEL eal fos E PJ HANDHELD SAME DUAL 2 FASTES DIRECTION ANTENNA TARGE Applied Concepts Applied Concepts Applied Concepts Applied Concepts Applied Concepts Decatur Electronics Decatur Electronics Decatur Electronics Decatur Electronics Decatur Electronics Decatur Electronics Decatur Electronics Kustom Signals Kustom Signals Kustom Signals Kustom Signals Kustom Signals Kustom Signals Kustom Signals Kustom Signals Kustom Signals Kustom Signals Kustom Signals McCoy s LAW LINE McCoy s LAW Ese ES a a A e e a a Basic att fe ejo Dual a SS Dual SL Stalker Dual DSR Direction Sensing Genesisi e Re Yes Xe Genesis I Remote Disp la E jepej GHS _ Genes ef f f Genesis B VP Genesis VP Directional Harley Davidson Genesis VP Directional Eae foe Co m mw Me No on ec i a Lh Eagle 1 al eS ee ee Golden Eagle
45. he application There is a main menu on top and live video from the video camera is shown beneath The main menu contains several items that each open a sub menu The Camera main menu item opens a submenu containing commands to initialize the camera These include commands to adjust camera settings such as brightness exposure time sharpness white balance hue and saturation The Mode main menu item opens a submenu to set the image type Image types define the image format type i e YUV RGB Mono as well as image size 640x480 320x240 or 160x120 The Rate main menu item 53 opens a submenu that sets the camera s frame rate i e 3Ofps 15fps 7 5fps etc The LPR main menu item contains commands to set the intensity threshold and also commands to start and stop recording plate numbers to a file There are two other application windows in addition to the main window They are the Processed Image window and the License Plate Detected window They are shown below Processed Image Window License Plate Detected Window icense Number 791GPB Fig 38 Processed image Fig 39 License number detected The Processed Image window shows live video from the webcam that has gone through image processing Image processing functions create a black and white image where pixel values are either black 0 or white 1 The License Plate Detected shows the last license plate number detected and the speed the v
46. he source If the source is moving toward the listener then vS is negative by convention in an inertial reference frame and the quotient in Eq 1 becomes larger the pitch heard by the listener increases However if the source is moving away from the listener then vS is positive by convention and the quotient of Eq 1 gets smaller the pitch heard by the listener decreases Conversely if the listener is moving toward the source of the sound vL is positive by convention the quotient in Eq 1 becomes larger and the pitch increases If the listener is moving away from the sound then vL is negative the quotient in Eq 1 becomes smaller and the pitch decreases In general police Doppler radar systems are set up in the manner shown below Conventional an iaia tlh 28 In this project we will be using the conventional police method of pointing the camera and radar gun down the road As you can see from the diagram police radar can detect vehicle speeds when the vehicle is up to a mile away The radar units we used in this project have a range from 100 ft to mile Problems with the Mattel Speed gun When the Mattel Toy s speed gun was taken out of it s housing fig 19 Ref 5 we discovered the following problems Fig 19 Inside of Mattel Radar Gun Fig 20 Radar Gun Circuit Board 1 The circuit board was a double layered board fig 20 Ref 5 2 The circuit contained an embedded ATmega88 microcomputer
47. ht from the sun causing regions of the image to appear darker Sun light intensity changes 11 according to the time of day or weather Therefore only the uniform constant light provided by an LPR light source should be allowed to enter the camera Another desired LPR light source characteristic is to output light with high intensity This is due to several factors For one the license plate will be distant from the camera More distant objects reflect less light back to the camera Two the camera will use a fast exposure setting in order to reduce image blur caused by the motion of the high speed vehicle Three the telephoto lens used by the camera to magnify the image as well as the filter placed in front of the camera will limit the amount of light received And four most CCD chips are not as sensitive to light in the near infrared range requiring more light be received for the same image contrast All of these factors will cause the license plate image to appear dark and lessen its level of detail However an LPR light source with very high intensity can offset these negative effects The more light that is emitted by a light source the more light will be received by the camera With more light the camera image will contain more detail making image processing routines more accurate Another desirable LPR characteristic is to project a beam of light that illuminates the entire width of the street lane This will ensure that as long as a vehicl
48. human surveillance to flag any suspect vehicles The purpose of this capstone project is to build a functional license plate recognition system capable of retrieving and recording a vehicle s license plate number the speed it was traveling and the date and time the vehicle was detected System implementation is to be done at the prototype level in which desired functionality is limited by the amount of resources available Documentation coinciding with this project will describe the project solution A description of all system hardware and software components and their specifications will be given The documentation will also include a description of the limitations of our system a description of a more optimum solution if more resources were available the test results of our system a description of currently available commercial systems the legality of traffic monitoring cameras and a description of other types of applications our system could be extended to Our project application will help make our roads safer It will provide a tool for law enforcement to monitor speeding vehicle activity and assist in tracking down violators License plate recognition is now a viable mature technology and is being used in a variety of applications today II Introduction The purpose of this project vvas to build a system capable of automatically recording the speed and license plate numbers of passing vehicles traveling down a roadway The speed and lic
49. i Recognition Speed Detection System l License Date Time FTY424 4 24 07 8 30A RST256 4 24 07 8 29A TRS842 4 24 07 8 28A SLG874 4 24 07 8 22A Fig 21 LPR SD system inputs and outputs Our LPR SD system is physically placed on the side of a throughway It continuously monitors passing traffic The system is composed of five main components as depicted in the 31 figure below a light source video camera computer serial interface circuit board and radar gun License Plate Recognition Light Source Speed Violation System Computer i Serial Interface Circuit Board SN a a I nv he Gili De I i Radar Gun H Fig 22 LPR SD system components The light source illuminates the license plate of a passing vehicle The video camera captures images of the front of the vehicle as the vehicle passes and sends those images to a computer The radar gun detects the speed of the vehicle and sends speed information to the serial interface circuit board SICB The SICB provides a means of passing the speed information to the serial port of the computer The computer processes images received from the camera and detects the license plate characters from the images The computer also receives speed information sent by the SICB The vehicle license plate number and speed are recorded in a file on the computer Our LPR SD system process flow is depicted in the figure below 32 LP
50. ies Python Series I X K KA M Kustom Signals KR 10SP X M MPH Industries Bee 36 A X K KA M NOTES 1 Any time distance feature has not been tested by the IACP testing program 2 Optional dual antenna capability has not been tested by the IACP testing program 3 All moving mode radars can also be employed in the stationary mode 4 Direction sensing feature was not evaluated for this model 5 Same direction and fastest target capabilities are not tested in the X and K bands 6 Both Silver Ring and Patch Ka band antennas have been tested Test results and analysis contained herein do not represent product endorsement by the ACP nor product approval or endorsement by the Nati Highway Traffic Safety Administration NHTSA the U S Department of Transportation the National Institute of Standards and Technology the U S Department of Commerce PLEASE NOTE CPL certification for any individual radar device will be voided by any third party modifications not specifically approved the original equipment manufacturer and the IACP 95 Appendix C Camera Setup Calculations Camera to vehicle distance 40 88 Feet Given Camera horizontal field of view 6 degrees Given License plate character width 1 125 Given Camera horizontal resolution 2 640 1 2 320 pixels Given Minimum number of pixels a license plate character can span and still be recognized 14 Y 320 Pixels 1 125 14 Pixels Y 25 71
51. imal intensity threshold The sticker was being seen as part of the license plate character To fix this the intensity threshold algorithm as described in V C 3 was written so that the optimal threshold intensity was calculated by the software and the registration sticker was no longer being seen as part of a license plate character Once this had been fixed the software worked well against stationary objects However further testing showed that if the license plate was visible to the camera for only a very short period of time the recognition software had trouble recognizing the characters This test case was done by moving a piece of cardboard quickly in front of and away from the license plate This was puzzling because at 30 frames a second the camera should be able to capture the license plate image no matter how fast I move the cardboard I discovered where the problem was by watching the application Processed Image window When I moved the cardboard away from the plate the license plate characters did not suddenly appear in the Processed Image window Instead the license plate characters faded in slowly even though images were being received at 30 frames per second This wasn t due to a bug in the code but is an inherent trait in CCD chips used by common video cameras It takes time for sensors in the CCD chip to react to changes in color Data may be pulled from the CCD chip at 30 frames per second however 61 changes i
52. ing Resource Guide Introduction Retrieved January 24 2008 from http www edmundoptics com techSupport DisplayArticle cfm articleid 286 42 Author Edmund Optics Date Unknown Longpass Glass Color Filters Retrieved February 16 2008 from http www edmundoptics com onlinecatalog displayproduct cfm productID 1512 43 Author ImagingSource Date Unknown FireWire cameras Spectral sensitivity and color formats Retrieved February 23 2008 from http www theimagingsource com en resources whitepapers download fwcamspecwp en pdf 84 Appendix A Our LPR SD System Component Specifications 85 The Unibrain Fire I board color camera was used for our LPR SD system unibrain www unibrain com Specification Fire i board color Fire i board monochrome Fire i board color RAW Device type IDC 1394 based Digital Camera Compliance Effective pixels H x V Pixel shape Hx V square 5 6 x 5 6 ym Ht square 5 6 x 5 6 ym Color yes RGB filtering Bayer i yes RGB filtering Bayer Resolution TV lines H x V 4 450 x 480 Optics provided separately Recommended lenses from Unibrain many models aiso from other manufacturers IR filter coated 2 1 mm all lighting conditions visible light only all lighting conditions IR filter coated 4 3 mm all lighting conditions visible light only all lighting conditions IR filter coated 8 0 mm all lighting conditions visible light only all lighting conditions not IR filter coated 12 mm avoid hal
53. ing radar gun Descriptions of the tests performed for each component are provided in the following paragraphs The license plate recognition software component underwent much testing through its development Several revisions to the source code were made as a result of this testing In the beginning tests were made against a stationary license plate The first version of the source code had several bugs For one it was not recognizing license plate characters in certain test cases It was found that if the background behind the plate was of a certain color or intensity the recognition software would fail This was fixed by changing the license plate recognition algorithms Instead of trying to extract the license plate region from the image the license plate 60 characters were first extracted This was made possible as defined in the algorithm given in Section V C 3 This algorithm works much better than the first algorithm because the intensity contrast between license plate characters and the license plate itself remains constant across all vehicle images whereas intensity contrast between the license plate and the surrounding region changes from vehicle to vehicle Test case results improved after this was fixed but there were still some test cases that failed It was found that when the registration sticker was placed closely to one of the license plate characters that character would be misrecognized This was a result of not having an opt
54. ion Layer Algorithms Much work was done at the application layer to provide the additional functionality and customization At the application layer the software follows the process flow as defined in figure 23 I would like to expand upon the diamond shape in Figure 23 that states Does license plate exist in image The algorithm for this decision block is provided in the steps outlined below 1 First convert the grey scale image received from the camera in to a 1 bit pixel map using an optimal intensity threshold value An example of this process is shown in the figure below The input image has pixels in the top two rows whose values are all greater than 50 and has pixels in the bottom two rows whose values are less than 50 The image processing routines receive the input image and output another image The pixels of the output image are set to 1 if the input pixel value is greater than the threshold value else they are set to 0 57 Input Image Output Image Image Processing 54 67 94 76 Intensity Threshold 50 67 87 69 89 45 34 42 29 67 25 48 32 Fig 42 Image processing using intensity threshold If the intensity threshold is set properly then all pixels of the license plate numbers will have a 0 value and the surrounding pixels will have a value of 1 as depicted in the image below and to the right Fig 43 Image processing using intensity threshold Retrieve contours from the 1 bit pixel map and pla
55. is added The federal court upheld the state courts opinion base on subject and jurisdictional grounds and did not address the constitutional issues Opponents to the use of photo radars and or red light cameras claim that there are alternatives to their use One alternative is to remove unwarranted traffic lights and replace them with four way stop signs However in general traffic lights are installed at intersections that 78 experience high traffic volumes or high speeds where stop signs are not appropriate A second alternative is to adjust the signal s timing to provide a longer yellow light Even where the signal s yellow phase had been lengthened people still ran the red light A third suggested alternative has been to change the geometry of the intersection to make the traffic signals more visible to drivers However speed and distraction are the main culprits resulting in drivers running red lights Proponents of these traffic control devices claim that the gain in safer roadways is measurable Indeed both the Insurance Institute for Traffic Safety and the National Highway Traffic Safety Commission supports their use The cameras photograph only the vehicle s license plate thereby reducing the privacy issues Adequate notice is given to the persons receiving the citation to allow them to obtain legal counsel The public highway does not provide for the same expectation of privacy that is accorded a person s home All drivers ope
56. is issued in a reasonable amount of time Various state laws have defined the meaning of in a reasonable amount of time For example the State of Rhode Island defines it to be within 14 days of the occurrence of the infraction Other states require the citation to be mailed within 48 hours of the infraction The U S Supreme Court to date has not commented on nor felt obligated to redefine common law practices thus legal challenges based on a strict interpretation of common law will continue to fail Further legal challenges to the use of photo radar and or red light cameras have contended that these devices violate a person s rights under the 4 6 and 14 Amendments to the U S Constitution The Fourth Amendment states in part the right of the people to be secure in their persons houses papers and effects against unreasonable searches and seizures shall not be violated For a photo radar red light camera to be considered constitutional under the AY Amendment it must provide the government with probable cause to assume that a crime has been committed Probable cause is defined under the 4 Amendment as a reasonable belief that a crime has been committed Reasonable belief is based on the circumstances Thus the reasonable belief that establishes the probable cause requirement is present when the police T11 officer has sufficiently trustworthy facts and circumstances such that a prudent person would conclude
57. ise detector in a second window The distance to the target is calculated from the time taken to make the round trip The reflected light signal levels are very low so the greater the reflectivity of a target the longer the range over which this target can be seen Therefore reflective targets will increase the range of each of the LaserAce IM OEM laser modules Sales Terms amp Conditions o LaserAce IM Tech Brochure We provide a set of standard systems which are designed for easy integration in all applications based on commonly e LaserAce IM Brochure required specifications Other variations are available and customisations can be provided for OEM integrators e Website Terms amp Conditions Please talk to us about your applications and needs so that we can show you how our LaserAce OEM Laser modules can help you 89 LXR CX800 Video Camera Extreme CCTV SX800 CX800 amp CZ800 Series Extended infrared LXR CCD Cameras Product Description Product Image LXR is short for the ELIXIR sensor or Enhanced Light Integrity for Extended Infra Red spectral response This new generation CCD marks a quantum advance in photopic response IR respoh e and dynamic range The benefits are clear no blooming no streaking no smearing The applications are extremely interesting night vision vehicle monitoring high speed surveillance license plate reading These 112 CCDs are high performance LXR extended infra
58. late numbers of passing cars and send the information to a centralized database The database would be located at a local police station where police officers could watch traffic flow in real time Each LPR system would be a node in the network that would communicate with other LPR systems using wireless technology Zigbee technology could be used for this application as well The diagram below depicts the network topology 67 e E a E SY S a TE Ko stem 5 ay J y Local s Za d 205 Network 3 7 Lr Vay N 7 SA ne S SE LPR l 3 SI System l N E l 4 1 LPR 2 LPR H T Ljy System _ System i I Mp ce S Yna St 1 LPR Sy om Me 1 ar Si l System Ps 1 g I N 7 I gt LA Mer I N t do Ca S E LPReerAcademy 1 Number 5 K amp System Elgmentary School S I Hudson Gal nty SI amp I Vocatioral School S s LPR 1a Si System rs G x 7 Police 7 gt z a N Station 250 m IS SA pd I e IS Ta a en SEES rere E TZ Yahoo 2008 Da Fig 49 LPR application of networked LPR SD systems LPR systems located furthest from the police station would send license plate and speed information to LPR systems located closer to the police station until the data reached the centralized data base at the police station Since Zigbee wireless technology offers ranges of up to one mile the LPR systems could be placed up to 1 mile apart The 250kbps bandwidth of
59. lation systems Disclaimer In this section we discuss the legality of license plate recognition systems Since we are not lawyers the material presented here is not to be construed to be legal advice nor is it intended to be an exhaustive treatment of the subject matter Research has shown that some of the major causes of motor vehicle accidents are speeding and failure to obey traffic signs and signals i e stop signs and red lights In 2002 over thirteen thousand people were killed in speed related motor vehicle accidents which resulted in a cost to the American taxpayer of 10 billion Statistics for 2003 have shown more than 176 000 people were injured by motorists that ran stop lights This has lead to an additional 14 billion dollar tax burden This is above and beyond all the pain and suffering resulting from these accidents The Insurance Institute of Highway Safety conducted a 9 month study using photo radars in Scottsdale Arizona The study was confined to an 8 mile stretch of the 25 mile long highway known as the Loop Prior measurements showed fifteen percent of the motorists were driving at speeds lt 10 mph above the posted limit By the end of the study period the percentage had dropped to less than 2 Similarly in Montgomery County MD the number of speeding motorists dropped by 70 However once the program in Scottsdale ended the average speeds went up to 69 mph in a 65 mph zone and more than 12 of the drivers were
60. le and signals the system camera to record an image of the passing vehicle The image is passed on to a computer where software running on the computer extracts the license plate number from the image License plate numbers can then be recorded in a database with other information such as time vehicle past and speed of vehicle License plate numbers can also be further processed and be used to control other systems such as raising a gate License plate recognition LPR systems are generally composed of four main components a light source to illuminate the license plate a video camera to capture images of passing vehicles a computer with image processing software and a trigger that signals when a vehicle is passing Light Source Video Camera Laser Trigger Computer Fig 1 General License Plate Recognition System II A LPR Light Source There are several commercially available light sources on the market today that provide the characteristics required by license plate recognition systems A good example is the Extreme UF500 infrared illuminator specs are given in Appendix B Some commercially available products include both the light source and video camera in one single unit A good example is EagleVision s Reg L1 License Plate capture camera specs are given in Appendix B Light source characteristics that are desirable for license plate recognition LPR are described in the following paragraphs The light sour
61. le could then be brought to the outside of the Ramsey Readout case This entailed drilling two one sixteenth inch holes into the top of the case with the holes spaced far enough apart to allow the ribbon cable to slip smoothly between them The plastic between the two holes was carefully filed away until the two halves of the case would close without binding or cutting into the ribbon cable An eight pin breakaway header was soldered to the opposite end of the cable The laptop computer has a serial port available for communication with peripheral devices To convert from the parallel output on the ribbon to a serial input needed by the computer we used a module from Parallax Inc figure 36 BASIC Stamp HomeWork Board Fig 36 Parallax HomeWork Board This unit is from a Parallax training kit for embedded microcontrollers It contains a programmable PIC microcontroller ucontroller a MAX232 chip and a serial port The Max232 49 chip handles the RS232 communication requirements The ribbon cable from the radar gun plugs into the black sockets marked P15 to P8 on the left side of the white breadboard The PIC pcontroller requires a program in order to function The BasicStamp2 modules are programmed with Pbasic Parallax Basic v 2 5 that is supplied in the HomeWork training kit The programming is done on a computer running the BasicStamp2 Editor software and is then downloaded to the PIC ucontroller on the HomeWork boar
62. ms The technology for these systems has advanced over the generations Now whole networks of traffic cameras are being deployed across cities to continually monitor vehicles on city roads Several cities in the United Kingdom including Northampton Bradford Stoke and the City of London have deployed ANPR systems A push is being made to have all roadways in the United Kingdom be monitored by ANPR cameras Currently information from all traffic cameras in the United Kingdom is stored in one central repository called the National ANPR Data Centre The data stored at this central repository is used in a multitude of ways Data can be accessed in real time by police providing a way to locate suspected vehicles in real time Data mining techniques are also applied against the central repository providing an endless flow of information Questions such as What traveling patterns did a certain criminal have 3 years ago can be answered In the United States the push for traffic monitoring cameras has not been as great Many citizens have criticized the effectiveness accuracy and legality of traffic monitoring cameras Traffic cameras however have made their way in to the U S mostly at toll booth and ez pass locations Also a new network of traffic monitoring cameras is being implemented in New York City called the Lower Manhattan Security Initiative It will contain hundreds of license plate readers along with thousands of other cameras for
63. n of each amplifier stage and negative feedback loops are used to control the gain and prevent the op amp from going into saturation The gain G in a negative feedback loop is controlled by the values of the resistors in the voltage divider configuration in the specific loop The gain G 1 R2 R1 The amplified signal leaves the last stage of the LM324 Op amp at pin 7 and is directed to the input pin of a 4093 Quad Schmitt trigger NAND IC A Schmitt trigger has the unique ability to convert any type of input waveform into a square wave output and at the same time acting as a noise filter The graph below figure 34 shows an arbitrary waveform at the top of the graph and the resulting output after passing through a Schmitt trigger The Schmitt trigger is a type of comparator IC that uses two independently set thresholds When the input waveform is below the lower threshold the Schmitt trigger s output is low When the input waveform is above an upper threshold the Schmitt trigger s output goes high The Schmitt trigger s output changes only at those times when the input waveform s trailing edge crosses the upper threshold 45 limits or when it s leading edge crosses the lower threshold The Schmitt trigger IC effectively converts the input signal to a digital signal i e highs 1 lows 0 Schmitt Trigger Operation Input Waveform Upper Threshold Lower threshold Schmitt Trigger Output Fig 34 Schmitt Trigge
64. n the CCD s pixels may take longer I discovered that by shining more light on the license plate the CCD was quicker to react and the software was able to recognize the license plate in a shorter amount of time The question remained of whether or not it would be quick enough to capture a speeding vehicle It should also be mentioned that the initial source code written had a memory leak After running the executable for more than five minutes all system memory was consumed and the computer would crash It was found that calls to the OpenCV library functions were consuming memory A certain OpenCV function had to be called during processing in order to free up memory and continue on After testing the license plate recognition software with a stationary plate testing was done outside along a roadside against moving traffic Testing was done on three separate days The results of these tests are given below The recorded results section shows what the software recorded to a file for each given test Day 1 April 12 2008 2 30PM 4 00PM Weather Partly Cloudy Light Source Used Sun Camera to vehicle distance 52 feet Speeds Tested mph 5 10 20 30 Plate Number 08CB10 Test Results Only the 5 mph test detected a license plate It detected 5 of the 6 license plate characters correctly Recorded Results 08C810 Sat Apr 12 15 05 50 2008 00 O8CB1 Sat Apr 12 15 05 51 2008 00 Day 2 April 20 2008
65. n was invented by Bryce K Brown of Decatur Electronics in March 1954 and was first used in Chicago Illinois by Patrolman Leonard Baldy in April 1954 It is interesting to note the State of Connecticut has a statute that states On and after July 1 1992 no hand held radar device that emits nonionizing radiation may be used in this state by any state or municipal police officer in the course of his employment for the purpose of preventing or detecting any violation of any law relating to motor vehicles C G S Title 7 Chapter 104 7 2947 Early radar guns used frequencies in the 2 to 4 GHz S band range Ref 10 Microwave ovens and some low powered communications devices also operate at these frequencies For this reason and the fact that the gun had a maximum range of only 500 feet the guns are now obsolete A vehicle moving at 55 mph would traverse this range in 6 2 seconds not much time for the old vacuum tube technology to respond to a stimulus X band 10 525 GHz radars were developed and deployed in the mid 1960 s They had better performance characteristics in bad weather when compared to K and Ka band radars but they also had wider beamwidths K band 24 15 GHz was introduced in the mid to late 70 s and had been used by the military during WWII These devices were very susceptible to weather conditions as a result of water vapor absorption at 22 24 GHz In 1992 the Federal Communications Commission expanded the previously
66. nce we have included data sheets for all transistors diodes and integrated circuits IC on the CD ROM attached to this report MICROWAVE OSCILLATOR SCHEMATIC DIAGRAM i BE gas oh METAL CAN ASSEMBLY 001 a a 8 ee 9 v 58 va Pinazz J1 Fig 30 Microwave Oscillator Circuit Diagram 40 ASH BLS Sk JUMPER fe T BB D a 8 pe a 4 D e e n CIO Fig 31 Assembled Oscillator The microwave oscillator circuit performs two functions First it produces a 2 6 GHz signal which is broadcast via a quarter wave dipole patch antenna Second it uses a quarter wave antenna mounted in a resonant cavity to receive the reflected signal from the object whose speed we want to measure Two one pound coffee cans with the ends cut out of one of them are soldered together to form the resonant cavity A stiff piece of wire is cut so that it extends approximately 1 1 inches into the can It is mounted 17s inches from the closed end of the can This forms a Va wave dipole antenna housed in a resonant cavity The metal walls of the coffee cans reflect the incoming radiation in a way that allows only those signals with wavelengths that are multiples of the can diameter to undergo constructive reinforcement This concentrates and intensifies the radiation prior to entering the detector circuitry The resonant cavity also helps narrow the angle from which the antenna can receive a signal which improves
67. oad then pressure sensors cannot be used It is also desirable to have a sensor with a very quick response time Magnetic sensors may not have a quick enough response time for fast moving traffic triggering the camera at wrong intervals It is desirable to have a trigger that can be located near the camera This will eliminate the need for costly extra support structures and long cable runs between camera and trigger Some laser range finders require they be placed directly over roadways requiring extra structures to support the system It is also desirable to 22 choose a trigger that will require the least amount of work to be incorporated into an LPR system Video cameras will require a computer and special software Care must be taken to choose the appropriate trigger for the application at hand Table 4 LPR Trigger Specifications Characteristic Desired Value Location Near camera Response time Extremely quick for fast moving traffic Obtrusiveness As unobtrusive as possible Work required to incorporate Minimal trigger in to system 23 IV Speed Detection Radar Concepts At the start of this project we discussed various methods for determining the speed of a motor vehicle including speed trailers fig 13 hand held radar units fig 14 laser rangefinders traffic classifiers traffic counters with road tubes ultrasonic detectors Passive Infra red PIR detectors and microwave radar units
68. ogen and sunlight visible light and close IR vision avoid halogen and sunlight Picture modes progressive VGA uncompressed modes selection by 1394 link Resolutions 640x480 320x240 160x120 Codings YUY RGB Monochrome 15fps 7 5 fps Auto Manual 1 3400s 1 31s Auto Manual 1 3400s 1 31s Auto Manual 1 3400s 1 31s Auto Manual Auto Manual Auto Manual OFF linear 1 ON visual 0 45 OFFilinear 1 ON visual 0 45 OFF linear 1 ON visual 0 45 6 modes OFF 6 modes OFF OFFilinear 0 ON visual manual OFF linear 01 ON visual manual Auto Manual Manual Reference picture generator Bars and ramps all modes ON OFF Power supply 8 to 30 VDC software switched by 1394 link Source by 1394 link extemal jack input by 1394 link external jack input by 1394 link external jack input Standby power 400 mW typ 450 mW max 400 mW typ 450 mW max 400 mW typ 450 mW max Operation power 900 mW typ 1 W max 900 mW typ 1 W max 900 mW typ 1 VV max 86 Appendix B Commercial Components 87 MSI Industrial GM965 Mini ITX Motherboard MS 9803 SPECIFICATIONS Processor Chipset System Memory VGA Expansion Slots Onboard IDE Onboard Serial ATA Onboard USB Onboard LAN Onboard Audio Back Panel I O Onboard I O Connectors Core 2 Duo Mobile Merom amp Penryn Celeron M Sa Merom Socket P 478 pin 800 533 MHz FSB Intel GM965 northbridge ICH8M southbridg
69. ons To answer these questions we would have to solve for the three distances shown in green in figure 26 i fi Camera 1 Camer t y ehicle Distance 3 Camera Field of Yiew 2 Maximum ehicle Travel Distance Fig 26 Three distances to calculate for camera setup Distance 1 the Camera to Vehicle Distance would tell us where to focus the camera on the street lane This distance was found to be 40 88 feet Distance 2 the Maximum Vehicle Travel Distance is the maximum distance a vehicle could travel within our camera s field of view This distance was found to be 6 69 feet From this distance we deduced that once a vehicle s speed reached over 136 84 mph it may be possible for the vehicle to pass the camera undetected Distance 3 the Camera Field of View Distance is the amount of distance covered by the camera s field of view This distance was found to be 51 42 inches From the Camera Field of View Distance we deduced that a vehicle could veer up to 19 71 inches from the center of its lane and still be sensed by the camera From these calculations we predicted that our 37 camera would be capable of performing both functions It would be possible to both capture high quality images of license plates for character recognition and also be used as a trigger to signal when an image should be passed to the character recognition routines Calculations for the distances shown in figure 26 are given in
70. or a Moving Sound Source Long Wavelength Small Wavelength Low Frequency High Frequency d Direction of Motion Fig 17 Doppler Effect Ref 14 The Austrian physicist Christian Andreas Doppler first described the Doppler Effect in 1842 He noticed how the frequency of a sound wave changed as the emitting object moved toward or away from a stationary listener When the emitting object was coming toward the listener the pitch or frequency of the sound increased But as the object moved away from the listener the pitch decreased The largest Doppler Effect is heard when the source is moving directly toward or away from the listener The frequency heard by the listener can be calculated from the following equation fL v vL v vS fS Eq 1 where fL is the frequency heard by the listener fS is the frequency emitted by the source Different sources have differing names for Dr Doppler On a NASA website he is Johann Christian Doppler Webster s Dictionary has him simply as C J Doppler Wikipedia gives his name as Christian Andreas Doppler 27 v is the speed of sound In dry air with a temperature of 21 C 70 F the speed of sound is 344 m s 1230 km h or 770 mph or 1130 ft s vL is the velocity of the listener vS is the velocity of the source If both the listener and the source are stationary then vL and vS 0 and fL fS The sound heard by the listener is the same as that emitted by t
71. oto Long I Chipin Lens Pass I Camera Filter Fig 7 Video Camera System As depicted in figure above light first passes through a long pass This filter blocks light in the short wavelength region less than 720nm and allows light with longer wavelengths the infrared region to pass through A graph of this effect is given below 13 Longpass Glass Color Filters 1 0 Passband t i 0 5 Stopband tii hs ke Ap i L L Passband Limit Cut Off Position Stopband Limit Fig 8 Longpass filter properties Ref 42 All wavelengths of light smaller than the stopband filter are prevented from reaching the CCD chip All wavelengths of light larger than the passband limit are permitted to reach the CCD chip An optimal long pass filter would have a passband limit whose value is less than the wavelength of light projected by the LPR system light source For example if an LPR system light source projects 850nm wavelength light the long pass filter should have a passband limit less than this value By blocking visible light a long pass filter eliminates the negative effects of visible light After light is filtered by the filter it next passes through the telephoto lens The telephoto lens magnifies the image Magnification is needed because vehicles will be imaged at a distance and license plate characters will need to be magnified in order for object character recognition software to function accurately
72. ovided examples of higher quality products that met those specifications We learned the physics behind light and radio frequency waves as well as camera terminology We implemented original algorithms in software to perform image processing and character recognition for an LPR type application We researched currently available free or almost free software libraries that provided the functionality we needed and integrated them in to our application We also soldered circuit boards and a radar kit to reduce the costs of buying commercial systems We created software to run on the serial interface circuit board as well Our system although only partially functional and having many limitations can easily be improved upon We have formed a good base and with the addition of higher quality products a more practical system could be implemented The software created can easily be reused It was 80 quite a fun experience to build the system and have something real and tangible at the end It was a great way to learn about science mathematics computer programming and electronics I hope our efforts will be continued by other students who partake on the challenge of building a license plate recognition system 81 References 1 Speed Trailer Decatur Electronics OnSite 400 Radar Trailer http www decaturradar com products index php category_id 3 Accessed 3 04 2008 2 Mattel Radar Gun http www hotwheels com coolstuff radargun aspx Ac
73. pture Definitive High Contrast Imaging Product Images REG L1 delivers definitive high contrast images of license plates Shown here wth EXMB 028B and EXMB 01 bracketry EXMB 028 not included must install with EXMB 015 for pole mount applications on The DHC Imaging technology in REG L1 captures plates from vehicles moving at up to 100mph a under any lighting conditions including highbeam headlight glare Applications Govemment buildings e Traffic monitoring Borders Parkades e Tol Booths Airports Hotels Highways Private estates Law enforcement 12VDC or 24VAC environments e Digital License Plates DLP e Automatic License Plate Recognition ALPR applications 92 HI TECH Solutions SeeCar Software Recognition Package PemgHi TECH mad solutions SeeCar Product Line SeeCar Software Recognition Package International Price List Jan 2004 SeeCar Software Recognition Package SRP The SeeCar SRP is intended primarily for OEM applications The SeeCar SRP provides an output string which includes the license plate number for each image received This product is available either as a Windows DLL Linux SLL or as a Windows CE DLL One SeeCar SRP license is required for each processor or PC station utilizing this software package An SDK software development kit with sample applications recognition player and documentation is provided together with the purc
74. puter Vision library provided computer vision functions to process live video images being received from the webcam Its functions provided the capability to segment license plate characters in to separate images This library is free and can be downloaded from www sourceforge net The Intel OpenCV library can be configured to use the Intel IPP Integrated Performance Primitives library This library provides low level image processing functions that are optimized for Intel processors A student edition of the Intel IPP library can be purchased for 25 The Serial library provides functions for communicating with a computer s serial port This library was used to retrieve data being sent by the radar gun The 56 Serial library was written by Ramon de Klein and was downloaded for free from www codeguru com The Tesseract library provided the functions for object character recognition This library converted images of characters in to actual text This library can be downloaded for free from http code google com p tesseract ocr The IIDC DCAM library provides communication to the FireWire video camera The library was developed at the Robotics Institute of Carnegie Mellon University It can be downloaded for free from http www 2 cs cmu edu iwan 1394 The library uses the IIDC DCAM protocol otherwise known as the Instrumentation amp Industrial Digital Camera protocol to communicate with the camera V C 3 Applicat
75. r Operation A comparator IC uses only one adjustable threshold level It s output changes each time the input waveform crosses the threshold See graph below figure 35 Given the same input waveform these graphs show the comparator IC to be prone to noise interference A noisy input signal close to a comparator s threshold level may cause the comparator to turn on and off unnecessarily 46 Comparator Operation Input Waveform Threshold Comparator Output Fig 35 Comparator Operation The signal from the Schmitt trigger is fed into a NAND gate which incorporates the signal from the calibration circuit The signal then goes to the enable pin of a dual Binary Coded Decimal BCD decade counter The counter drives two separate LED readouts the tens place and the ones place When the ones value reaches 9 the counter rolls over and places a high value on the enable pin of the second half of the counter This half operates the tens place value on the LED display Combined these two LEDs form the visual display of the vehicle s speed This completes the brief description of the circuits in the radar gun The unit according to Ramsey Electronic is capable of measuring speeds up to and above 99 mph We did not test the accuracy of this claim The User s Manual suggests one way of testing the radar gun at higher speeds is to point it at aircraft on landing approach Since the September 11 2001 attack on the World Trad
76. rate their vehicles in plain and open view Finally in all states of the Union speeding and running traffic lights is against the law Connecticut was the first state to adopt speed laws in 1901 12 mph in the city and 15 mph in rural areas Ref 23 The preceding was a necessarily brief overview of the legality of these traffic control devices For those interested in this area we urge you to follow up with the references and resources provided at the end of this work 79 VIII Conclusion License plate recognition systems exist today for a wide range of applications The technology behind LPR systems has advanced over the years and has greatly increased in accuracy Most commercially available systems sold today are sold by system integrators who must configure and customize systems for the application being implemented We started our capstone project by first defining a semi original LPR application specification The specification required a system be built to record the speed and license plate numbers of passing vehicles We researched currently available systems for commercial use and found their products to be too costly The only way to build a system within our budget constraints was to design a limited system from scratch In so doing we learned the intricacies of every component of the system We researched what components we could afford and purchased those components We defined optimal specifications for those components and pr
77. rea window weight AGC 30 dB SAGC 36 dB AGC 30 dB SAGC 36 dB AGC 30 dB SAGC 36 dB 10 C to 50 C 10 C to 50 C 10 C to 50 C Operational Range 14 F to 122 F 14 F to 122 F 14 F to 122 F Humidity Range Up to 80 RH Up to 80 RH Up to 80 RH Power Supply 12 VDC 10 12 VDC 10 12 VDC 10 12 VDC 29W 12 VDC 29W 12 VDC Lens standard C CS Mount Type Lenses C CS Mount Type Lenses C CS Mount Type Lenses 5 57mm x 51mm x 38mm 57mm x Simm x 38mm 57mm x Simm x 38mm 22 x 20x15 27x20x15 27x20x15 Weight 402 1109 402 1109 90 UF500 Infrared Illuminator Extreme CCTV UF500 Series infrared illuminators Key Features sm e High output to 250 meters 820 ft illumination distance e Range of beam patterns from spot to wide angle e Range of filters from 730 nm to covert 950 nm Low operating cost using less power e Even lllumination US Patent 6158879 e No foreground over exposure No background under exposure e Rugged and weatherproof e Long bulb life at 3 000 hours e Low operating voltage at 28 6 VAC Extends the dynamic range of CCD cameras in night time conditions Product Description The UF500 series of illuminators for CCTV applications is specially designed for covert or semi covert operations using special gold optics and high efficiency quartz halogen bulbs for unsurpassed night viewing up to 820 ft The unique cosec lens reverses the inverse square law to
78. red board cameras designed for use in cover night time or dark room installations Their low light capability rivals that of other high performance cameras with military spec performance T cx800 t sx800 T cze00 LXR boards also have low smear characteristics made possible by its wide dynamic range Excellent bright light Lenses shown from left performance allows for use without mechanical auto ins 8 lenses 1 VASSO 1 3 Varifocal Auto Iris 5 50 mm 2 VA358 113 Varifocal Auto Iris 3 5 8 0 mm 3 VA8551 112 Varifocal Auto Iris 8 5 51 mm Specifications SX800 Series CX800 Series CZ800 Series LXR 112 CCD Mono Color IR Moni 1 Cdoroty I Dual pass Color IR Image Sensor Video Signal Ouput 1V p p 75 ohm 1V p p 75 ohm z 8 811 H x 508 V EIA 811 H x 508 V EIA 811 H x 508 V EIA CCD Effective Pixels 795 H x 596 V CCIR 795 H x 596 V CCIR 795 H x 596 V CCIR Sync System DC Internal DC Internal DC Intemal Min Illumination 0 01 lux F1 2 SAGC on 0 1 lux F1 2 SAGC on 0 1 lux F1 2 SAGC on nee Zero 0 lux from Zero 0 lux from IR Sensitivity 780 nm 1050 nm NJA 780 nm 1050 nm Resolution 600 TVL 480 TVL SIN Ratio gt 48 dB 5 1 60 to 1 100 000 EIA 1 60 to 1 100 000 EIA 1 60 to 1 100 000 EIA Electronic Shutter 4 50 to 1 100 000 CCIR 150 to 1 100 000 CCIR 4 50 to 1 100 000 CCIR Backlight Compensation Auto Detect On off Histogram plus 225 a
79. s characterized by unmatched clarity Using solid state Metaphase LEDs REG L1 achieves an operational range from 12f to 75ft previously unattainable for any LED based capture system Combined with Extreme s Ambient Rejection technology REG L1 provides high contrast license plate capture across the complete specirum of ambient lighting conditions from total darkness to direct glare from sunlight or high beams Consisting of a 1 2 LXR CCD the high speed optical engine within DHC Imaging captures plates from vehicles moving up to 100mph 160kph REG L1 s breakthrough speed capability now enables effective license plate capture for highway and other high speed applications Additionally DHC Imaging has capture capability for not only conventional plates but also Digital License Plates DLPs REG L1 is housed in a weather sealed unit compliant to NEMA4 proven for successful application in extreme environments The high efficiency Metaphase LED array eliminates the need for routine bulb changes while consuming an average of only 24 watts allowing REG L1 to operate at either 12VDC or 24VAC REG L1 integrates seamlessly with industry standard DVRs IP video servers and wireless broad equipment The DHC Imaging technology is precision engineered to deliver high contrast images for in intelligent software platforms such as REG ALERT for Automatic License Plate Recognition ALPR applications REG L1 DHC Imaging License Plate Ca
80. s flash the driver s speed as well as a customized message according to the driver s speed Fig 47 Example of variable message traffic displays Our system would flash the driver s speed as well as display the driver s license plate number in the customized message An example message could read License Number FDK425 has been recorded for speeding The effect would create more of a fear factor for the speeding driver Our speed display sign could be built on top of our current license plate recognition system The new system design would consist of a commercially available traffic display similar to the one shown above customized to communicate with our system The new system is depicted in the diagram below 65 Traffic Display LPR Speed Detection System I I I raTa Fig 48 LPR application with traffic sign Wireless technology would be needed to communicate between the LPR System and traffic display due to the physical distance needed between them Since the LPR system detects license plates at around 40 feet it would have to be positioned further in front of the traffic display to provide the time delay needed to display the message for several seconds for the driver to see Over 354 feet separation would be needed to display the message for more than 3 seconds for a car traveling 80mph Only a small amount of bandwidth would be needed for the wireless communication The LPR system would only
81. same video camera is also being used as the trigger component then it should have a very fast frame rate This will ensure an image of the vehicle is captured before passing the camera A summary of desirable LPR video camera characteristics is given in the table below When a video camera contains these characteristics a high quality image of the intended license plate will be captured Table 2 LPR Video Camera Characteristics Characteristic Desired Value Long pass filter All visible wavelengths of light are blocked Telephoto Lens Powerful enough to image license Magnification plate characters at a distance Telephoto Lens Field of Wide enough to capture license plate View when vehicle travels within its lane 19 Telephoto Lens Aperture Small enough to provide required depth of field but large enough for fast exposure time CCD Sensitivity Minimum High sensitivity Low LUX value for Illumination infrared lighting Signal Output Digital or computer protocol for clean high resolution image Frame Rate optional If camera is also being used as a trigger it must have a high frame rate Trigger Port optional Most cameras have a trigger port that is used to signal the camera when to take a picture CCD Resolution High enough to provide acceptable level of license plate detail when capturing an entire lane width LII C LPR Computer A computer specialized for licens
82. that the suspect has or is committing a crime The Sixth Amendment to the U S Constitution states In all criminal prosecutions the accused shall enjoy the right to a speedy and public trial by an impartial jury of the State and district wherein the crime shall have been committed which district shall have been previously ascertained by law and to be informed of the nature and cause of the accusation to be confronted with the witnesses against him to have compulsory process for obtaining witnesses in his favor and to have the Assistance of Counsel for his defense emphasis added A legal challenge to the use of a red light camera was brought up in the case of Dajani v Maryland The court dismissed the case based on the lack of standing to sue based on the plaintiff s failure to show threat of immediate or future injury Plaintiff Dajani then argued in federal court that the traffic code was unconstitutional based on the Sixth Amendment and the Fourteenth Amendment All persons born or naturalized in the United States and subject to the jurisdiction thereof are citizens of the United States and of the State wherein they reside No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States nor shall any State deprive any person of life liberty or property without due process of law nor deny to any person within its jurisdiction the equal protection of the laws emphas
83. tions requiring primarily distance measurement e Robust over conventional sensors Easy to integrate Long or short range measurement Can be customised to suit customers requirements Distance Measurement LaserAce IM OEM laser modules can be configured to Fixed Distance Camera Triggering output range speed and height of vehicles or objects Law Extbirement and may also be set to trigger cameras in tollbooth or law enforcement applications The laser sensors can also be hi eni ndi i i it further integrated to produce vehicle profiles and scans classify and identify them count axles over height i ae pie p ollision Avoidance detection and much more Airbome Laser altimetry Kapsch TrafficCom based in Austria use the LaserAce IM 300 s for triggering cameras in toll booths DI R Wieden of Kapsch TrafficCom commented LaserAce IM is easy to integrate and to adopt according to the given surroundings conditions of the location The product perfectly fits the requirements for vehicle detection and camera triggering that we have defined The primary reasons we have used the Sighting Scope LaserAce IM laser modules are because they e Laser Pointer can accurately detect vehicles and classify truck e Extra Cable Length versus passenger car without requiring a second e Black Transit Case mounting structure e g gantry or installing o Flying Lead Cable something in the roadway for m
84. traveling at 75 mph or more As a result of such studies and in order to prevent the violation of traffic laws the 75 Federal Highway Administration and the National Highway Traffic Safety Administration have indicated their support for automated enforcement systems Numerous states Arizona California Colorado Delaware Hawaii Illinois Maryland New York and Virginia have enacted statutes allowing the use of these automated systems to enforce traffic laws Ref21 Connecticut statute C G S Title 14 Chapter 248 14 219c Vehicle Highway Use does not specifically mention photo radar or red light cameras but the statute s phrase any other speed monitoring device approved by the Commissioner of Public Safety could allow for their use In the 2005 legislative session House Bill 5744 Ref 31 attempted to introduce devices that are designed to automatically record the image of the license plate of a motor vehicle that is entering an intersection in violation of a traffic control signal However the bill was never signed into law In the January 2007 session raised bill 1443 was introduced in the State Senate where it has been referred to the Joint Committee on Judiciary it has not left the Committee In November 2007 Connecticut Governor Jodi Rell proposed installing automated traffic enforcement devices along a stretch of Interstate 95 in East Lyme where I 95 I 395 and Route 1 intersect This proposal is being reviewed
85. ulti lane free flow applications Most other laser detector devices must be mounted pointing straight down and thus in order to trigger a camera mounted above a lane requires a second mounting structure one Resources a for the laser and a different one for the camera o Active miga The MDL laser eliminates the need for the second Mine Shq t Measurement gantry and allows us to mount the trigger device right next to the camera housing Quote from JAI Pulnix AN Denmark Caen trigger Alongside traffic applications the Laser ce P IM OEM laser module is used in military security construction and e Axel counting Load height aviation markets From a target designator motion detector surveying tool and altimeter each market segment has e Cable detection e LaserAce IM Front e Car to car measurement its own special requirement Here at MDL we are aware that no two applications are exactly the same so we work with our OEM partners to provide unique solutions to their individual applications and are always willing to help Laser4ce IM OEM laser module is cost effective accurate fast and environmentally sealed to IP67 making it the e Laser speed gun most robust sensor on the market today Over height detection The OEM laser modules use time of flight technology put simply it measures the time taken for a very short pulse Silo Messurement of infrared laser light to travel from one window in the module to a very low no
86. urce the license plate no longer appears more illuminated than the rest of the objects in the image The 10 reflective paint effect greatly increases the luminescence of the license plate compared to other objects in the picture when the angle between light source and camera aperture is reduced A highly luminescent license plate makes license plate detection based on contrast thresholds much more accurate Contrast thresholding will be discussed later The reflective paint effect is so pronounced that it can cancel out the negative effects caused by unclean license plates Another desirable LPR characteristic is to project near infrared light between 720nm 1100nm Near infrared light will not blind the vehicle driver because its wavelength is outside the visible range Also light from other sources will not interfere with the light from the LPR light source As depicted in the diagram below a filter placed in front of the video camera will block all visible light and allow only near infrared light to pass through LPR Light Source SY TN n E Filter 0 LPR Video te Camera i PRO Fig 6 Visible light is blocked from the camera Visible light is blocked because sources of visible light such as the sun do not project light in a uniform constant manner Character recognition software is less accurate when images received from the camera contain lighting that is non constant or non uniform Trees could block lig
87. urrent Practices for Setting and Enforcing Speed Limits Special Report 254 http www nap edu catalog 11387 html 20 Calculating the Doppler Effect http physics about com od wavessound a dopplereffect htm 21 Communities using red light and or speed cameras as of April 2008 http www iihs org research topics auto_enforce_cities html 22 Kane A Automated Traffic Enforcement in the United States IBEC ITS World Congress London England October 8 2006 23 Speeding is a SNAPI http www photocop com speed htm 24 A Look Under the Hood of a Nation on Wheels ABC News Time Magazine Washington Post Poll Traffic 1 31 05 25 Turner S and Polk A Overview of Automated Enforcement in Transportation ITE Journal June 1998 26 Stark L and Wachter D Caught on Click Cameras Nab Speeders Controversial Cameras Catch Speeders in the Act ABC WorldNews with Charles Gibson Jan 31 2008 27 McDonald A M and Cranor L F How Technology Drives Vehicular Privacy A Journal of Law and Policy for the Information Society Fall 2006 28 Jones D J Patrolling Traffic by Camera An Analysis of Photo Enforced Traffic Citations and the Common Law Requirement That a Warrantless Misdemeanor Arrest Take Place Immediately de la Revista de Derecho Puertorriqueno 2006 29 Abbate J A Esq The Red Light Camera Automated Traffic Violation Monitoring System Rhode Island Bar Journal 83 30 Webster G These speed cops
88. y a signal 42 up to 100MHz Once the signal has been amplified it is capacitively coupled to the signal output jack J1 and sent to the readout circuit The NE021 transistor the patch antenna and a few passive components form the remaining part of the circuit The NEO21 transistor is configured as an oscillator and it produces the 2 6 GHz signal This signal is passed to the foil patch antenna mounted directly on the printed circuit board The signal is coupled to the waveguide and forms the initial radar beam The Readout Circuit Figure 32 shows the completed readout circuit board Figure 33 shows the speed readout circuit diagram Fig 32 Assembled Readout Board 43 LED SCHEMATIC DIAGRAM Fig 33 Readout Circuit Diagram 44 I will discuss the pathway the input signal takes through the readout circuit from the input jack to the 7 segment LED display For brevity I will ignore the headphone calibration and gain control circuitry Two six volt dry cell lantern batteries connected in series powers the readout display The input power is separated by a voltage divider circuit formed by resisters RI and R2 to give a 12 volt supply and a 6 volt supply needed by the integrated circuit IC chips The signal from the microwave oscillator enters the readout circuit via the signal jack J1 The signal is amplified by passing through all four stages of an LM324 Quad Op Amp The input signal is applied to the non inverting pi
89. ypes of light produce the same effects when shown on reflective paint The reflective paint on the license plate causes the license plate to be highly lit when illuminated by a light source that is placed near the camera aperture This holds true whether the light source is emitting visible light or infrared light It will make it easier for the image processing algorithms to extract the license plate characters from the image However using visible light for a light source is impractical Shining bright visible light at passing vehicles 35 is dangerous and may temporarily blind the driver of a car Also light from external light sources will interfere with the light coming from our light source Light from the sun or another vehicle s headlights can interfere with our light source light lowering the accuracy of the image processing algorithms Using visible light also changes the requirements on our system video camera As previously discussed most LPR cameras are sensitive to near infrared light and block all other wavelengths of light Since our system is using visible light to illuminate the license plate our camera must also be sensitive to visible light For our system video camera we used a UniBrain FireWire webcam Complete specifications are given in appendix A We chose this camera for several reasons The camera only cost 105 and was within our budget constraints It was also able to retrieve images at 30 frames per second We neede
90. ystem that could be built significantly cheaper and created several original software algorithms These algorithms are described in section V C 3 Application Layer Algorithms Another benefit of developing our system from scratch was the depth of detail we learned about every component in our system These details were necessary to learn in order to customize and configure each component to be optimized for our project s application A good base foundation in the physics behind lighting and optics image processing object recognition radar technology computer programming camera terminology and electronics was required to perform the tasks at hand The disadvantage of not using commercially available systems is the low quality of the components we used in our system There are inherent limitations in our system that prevents it from being a practical solution There was much work done to implement our project s system A list of tasks that were performed is given below Define our project application requirements Learn techniques used in license plate recognition systems from other papers Research currently available commercial systems Determine the components needed for a limited system Find and purchase components Build a radar gun from scratch Build and program a circuit board used to connect the radar gun to the computer Research image processing techniques Find available free software libraries to perform the necessary im

A License Plate Recognition and Speed Detection System

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