STH-MDCS2/-C Stereo Head User's Manual
Contents
1. amp lurninurm 1 4 20 center mounting hole sas 0 31 offset mounting holes ce Irrr b qn peu D 237 liom 22 STH MDCS2 USER S MANUAL 2004 VIDERE DESIGN 190 g 6 7 ithout 10 Technical Specifications Weight 71 m 5 A 0 10 1 Specifications Linux kernel 2 4 2 6 SVS software MSW 98SE ME 2000 and XP 1 2 format CMOS Micron MT9MO001 1280x960 active area Progressive scan Color or monochrome Digital Camera Specification Version 1 30 10 2 Imager Response Color 1280x960 640x480 Formats 8 bit monochrome or Bayer color pattern 3 75 7 5 15 30 Hz Quantum Efficiency Color Frame Rates 3 125 6 5 12 5 25 Hz Max 7 5 Hz at 1280x960 Imagers Blue LA LANI IZ NV INL iy A TA LL LI LIS Wavelength nm Exposure 1 line time to full frame Sensitivity 2 1 V lux sec monochrome Synchronization Internal pixel locked External 60 us 6 0 mm F 1 4 C mount included 3 5 mm 8 mm 12 mm and 16 mm lenses optional 5 5 E 4 e d LL E E 5 C 1 725 high x 5 2 long x 1 3 deep 23 STH MDCS2 USER S MANUAL 2004 VIDERE DESIGN 10 3 Imager Response Monochrome 10 4 Filter Transmittance Thickness in mm Quantum Efficiency Monochrome 8 zo RU Transmittance Internal Transmittance T e E E E d Lil E a z2. Focal Wet 15 60 5 Range 0500 0000 15 6 9 1 T TEATE 15 7 Us erControls ems 17 7 1 0 D TENURE 17 T2 Gamma Correctioh earna Siete dst he ore sien 17 7 3 Video Digitization Parameters eeessssssssseeeeeeeeeeeeee 18 02004 VIDERE DESIGN 7 4 DUDSQIHDIITIE begeren 9080200519 00000 00 1800105 IUIS SPA o IIS dia M deas Eo S eaEE 19 7 5 Erme Re Sane 19 7 6 0 a 19 amp Interface Software A Pl sccsccssccissscecicsdsacctesssecicsdesnccecescecdesdestectesssace 21 9 Physical Dimensions and Mounting 1313071 22 10 Technical Specifications ecce eee eee eee eene eee 23 LOST ieu roa dubicemp dubia ioa duties 23 10 2 Jimaser Response COolOR oup uet psit eiie esas 23 10 3 Imager Response Monochrome eeeeeeeee 24 TOA Filter LransmittaflGe eec evoca cen ri eda aM ra E Dead tea ouis 24 11 Technical SUD POM coin D nn 25 STH MDCS2 USER S MANUAL Figures and Tables Figure 2 1 SVS main program WindOwW cccccccccccccecsssssseesseeeeeeeeeeeeeeeeeaas 5 Figure 3 1 Physical layout of the STH MDCS2 C stereo head 7 Figure 3 2 Schematic of the STH MDCS2 C electronics 8 Figure 4 1 Host PC low level software structure eeeeeeeeeess 10 Figure 5 1 External power supply connections sssseeeeeeeeeeeeeeeees 13 Figure 6 1 Range resolution in mm as a function of distan
3. V Wavelength nm 0n a n 200 300 400 500 600 700 ano 900 1000 1100 VWereelength in nm 24 STH MDCS2 USER S MANUAL 11 Technical Support For technical support please contact Videre Design by email or FAX Videre Design 865 College Avenue Menlo Park CA 94025 Fax 650 323 3646 Email support videredesign com Technical information about stereo algorithms and stereo calibration can be found at www ai sri com konolige svs 25 2004 VIDERE DESIGN
4. bus PCI cards or built in ports for desktop machines normally supply this power For PCMCIA cards PC Cards and laptops with a built in port no power is available In this case external power must be supplied see Section 5 3 The PC operating system will normally recognize the STH MDCS2 and install the correct system drivers Please see the Videre support web pages www videredesign com support htm for specific information about installation for your OS At this point you should check to see that the STH MDCS2 has been recognized by the system 2004 VIDERE DESIGN Start the SVS main program smallv exe or smallvcal exe on the host computer You should see a screen as in Figure 2 1 The message window should indicate that the DCS Digital Stereo Interface is present If not go back to software installation Section 4 2 and follow the instructions for configuring the correct capture library Pull down the Input chooser and select the Video option If everything has been set up correctly the SVS interface will recognize and configure the stereo head and a success message will appear in the info text window If not the Input chooser will go back to None and an error message will appear in the info window Please see Section 4 for troubleshooting To view stereo video press the Continuous button Left and right images should appear in the application windows If the message Image timed out appears then
5. can be connected at any point in such a topology At a maximum it will need about 60 of the bandwidth of a 400 MBps connection 5 2 IEEE 1394 Host Interface The host computer must have an available 1394 port Some portables and desktops come with built in ports If these are 6 pin ports they can be connected directly to the STH MDCS2 C Sony laptops also support an alternative 4 pin 1394 cabling which has the signal pins but no power There are adapters that convert from 4 pin to 6 pin styles these adapters use an external power supply transformer If the host PC doesn t have a built in 1394 port one can be added by installing a 1394 PCI card or PCMCIA card for laptops 1394 PCI cards have 6 pin ports and supply power PCMCIA cards do not have the 12 02004 VIDERE DESIGN capability of supplying power and come with an adapter for supplying power to the 1394 cable through a wall transformer Any 1394 card is suitable as long as it conforms to OHCI open host controller interface specifications All current cards do but some older cards may not 5 3 Supplying Power Power to the STH MDCS2 is supplied through the IEEE 1394 cable The IEEE 1394 system must supply this power about 1 Watt There are two typical PC systems desktops and laptops e Desktop PCs have either a built in IEEE 1394 port or a PCI card with IEEE 1394 ports In both cases the desktop should supplysufficient power to run the STH MDCS2 e aptop
6. light on the image will be adjusted by changing the exposure Te SRI SVS Stereo System File Device Wideo ideo Buffer Rate 0 0 Left Color Sv version 3 2h DCS Digital Stereo Interface Right Color 5i Function Mone 3D Display Horopter Window Au or Swap Mart X off 4 o0 H Color Capable Muti Scale Frame size Gamma correction Sampling mode Figure 7 2 Frame size and sampling controls in the main capture window STH MDCS2 USER S MANUAL 7 4 Subsampling In many applications it is not necessary to work with the the full 1280 x 960 image The CMOS imagers are capable of sampling the pixels in the array Sampling allows the video stream to send less data for faster frame rates or less bus activity A sampled image shows the same scene as the original image but it uses fewer pixels to do so and has less detail Binning is a subsampling technique in which several adjacent pixels are averaged into one Binning reduces video noise sometimes quite substantially Binning is available on the host PC the larger image is first transferred on the IEEE 1394 bus then binned down The binning 1s color aware for the STH MDCS2 C so that pixels of like color are combined Sampling differs from subwindowing which picks a rectangular portion of the image but doesn t change its resolution The STH MDCS2 has one subwindow mode in which the center 640x480 subwindow of the imager is chosen Using the subwin
7. practical focal length for the STH MDCS2 The following table shows the FOV for some standard focal lengths STH MDCS2 USER S MANUAL 02004 VIDERE DESIGN Lens focallength Horizontal FOV Vertical FOV 3 5 mm 87 1 deg 71 1 deg so dsi a2 00 Table 3 Horizontal and vertical field of view for different lens focal lengths 16 STH MDCS2 USER S MANUAL 7 User Controls The CMOS imagers are fully controllable via the 1394 interface User programs may input color images STH MDCS2 C only set video digitization parameters exposure gain red and blue balance and subsampling modes All of these parameters can be set with the SRI Small Vision System They are also accessible to user programs through the capture API Section 8 User controls for frame size and sampling modes are on the main capture window dialog Video digitization controls are accessed through a dialog invoked with the Video menu item Figure 7 1 shows the dialog 7 1 Color Color information from the stereo digital head STH MDCS2 C only is input as raw colorized pixels and converted by the interface library into a Video Parameters Red Blue E EE Figure 7 1 Video Parameters dialog 17 2004 VIDERE DESIGN two monochrome and one or two RGB color channels The primary color channel corresponds to the left image which is the reference image for stereo The right image color channel is also available The color ima
8. various frame rates Using this table it is possible to determine the maximum number devices that can stream 0 simultaneously For example at 15 Hz and 640x480 resolution a maximum of 3 STH MDCS2 devices can send video information at the same time The bus bandwidth consumed by a device is more than would be expected from just counting the number of bytes in each frame because there are Frame Bus MB per 30 25 15 12 5 7 5 6 25 3 75 size frame Hz Hz Hz 3 125 Hz stereo 640x480 0 683 MB 20 5 MB 10 2MB 5 12 MB 2 6 MB 280x960 2 73 MB 205 MB 10 2 MB Table 2 Bus bandwidth requirements at different frame rates 02004 VIDERE DESIGN blank cycles on the bus when no data is being transmitted even though the bandwidth is reserved Thus it makes no difference whether the rate 1s 30 Hz or 25 Hz the bus bandwidth consumed is the same STH MDCS2 USER S MANUAL 4 Installing the 1394 Host Card and Capture Software The STH MDCS2 C connects to a host computer via a digital 1394 interface The host PC must have a 1394 port and software to interface to the video stream from the camera This interface software presents the video stream from the 1394 hardware as a set of stereo frames to the user program see Figure 4 1 The STH MDCS2 C comes with interface software for either MS Windows 98SE ME 2000 XP or Linux 4 1 1394 Hardware and Drivers Before installing the software interface the PC must be equipped with a 1
9. with 50 Hz electrical line frequency e Stereo calibration information can be stored on the device and downloaded automatically to the PC e IEEE 1394 interface to standard PC hardware carries power and commands to device data to PC e Standard C CS mount lenses interchangeable focal lengths from 3 5 mm to 50 mm e Fixed 9 cm baseline e Anodized aluminum alloy chassis high rigidity STH MDCS2 USER S MANUAL 2 Quick Start The STH MDCS2 C normally comes assembled with the lenses mounted If you need to change the lenses or if you are supplying your own please see Section 6 1 To set up and test the STH MDCS2 C you will need the following 1 Pair of C mount lenses for 1 2 or larger imager normally included and mounted with the STH MDCS2 C kit 2 Host computer with an IEEE 1394 PCI desktop or PCMCIA laptop card OHCI compliant or a built in IEEE 1394 port 3 IEEE 1394 6 pin to 6 pin cable 4 Small Vision System installed on the host computer Install the IEEE 1394 host card if necessary according to the directions in Section 4 1 Install the Small Vision System software see Section 4 2 If the lenses are not mounted on the device follow the directions in Section 6 1 for installing them Plug one end of the IEEE 1394 6 pin video cable into the 1394 jack on the back of the STH MDCS2 C and the other into an IEEE 1394 port on the host PC Note The STH MDCS2 draws power from the IEEE 1394
10. 394 port If there is one already present a built in port then you can skip this section Otherwise you have to install a PCI or PCMCIA card The card must be OHCI compliant which all current cards are 4 1 1 MS Windows Hardware Installation For the most up to date information about installation please see the Videre Design website www videredesign com support_svsmsw htm MS Windows 98SE ME 2000 or XP is required For a PCI card insert the card into a free PCI slot with the computer power off and start the computer With a PCMCIA card insert it into the PCMCIA slot In either case the New Hardware wizard will walk you 1394 To video user stream program Low level STH MD1 PC 1394 interface driver software Hardware Figure 4 1 Host PC low level software structure 10 2004 VIDERE DESIGN through installation steps for the low level drivers You may need your MS Windows OS CD to install some files The STH MDCS2 must be powered from the IEEE 1394 bus Desktop PCs supply power to the bus laptops do not See Section 5 for information about cabling and power for the IEEE 1394 bus 4 1 2 Linux Hardware and Driver Installation Linux kernels 2 4 or 2 6 kernels are required for operation Please see the Videre Design website www videredesign com support_svsInx htm for current information GCC 3 x is recommended as the compiler there is a separate SVS distribution for GCC 2 95 x but it is n
11. 80 and 320x240 In both cases the STH MDCS2 transmits the full 640x480 image For 320x240 the SVS interface software uses binning to reduce the image 7 5 Frame Rates Frame rates from the STH MDCS2 C depend on the frame size Table 4 shows the frame rates available for each of the frame sizes Note that a 50 Hz option is available see Section 3 3 7 6 Firmware Parameters There is one firmware parameter that affects the overall behavior of the STH MDCS2 e 50 Hz operation Resolution Frame Dec on Bin on Frames per Second imager PC 1280 x 960 35 75 640 x 480 315 75 15 30 0420 Ful yes yes 375 75 15 30 6x48 no no 375 75 15 30 320x240 ae no ye 37575 15 30 Table 4 Subsampling modes and frame rates for the STH MDCS2 The greyed out line is a non default mode accessible with the SetSample function STH MDCS2 USER S MANUAL This parameter can be changed by using the Firmware Parameter dialog accessible from the smallv menubar Choosing this menu brings up the dialog which is shown in Figure 7 3 The dialog lists many of the internal parameters of the device which are Sets Device Type FW Version 0203 Camera Version 4M Camera Imager 1 Device Type Steren PE Firmware Parameters Calor Capable yes Device ID ERT 6 Device Parameters Max Width 1286 hax Height 0 Lettered Figure 7 3 Firmware parameters
12. 94 Interface a Electronics module Digital 1394 Video commands Stream 1394 Digital Cable Figure 3 2 Schematic of the STH MDCS2 C electronics data type sending the left stereo image in Y and the right image in the UV pixels Each image from the stereo camera has 8 bit pixels In the case of the color version STH MDCS2 C the color information is encoded as a Bayer pattern in the same 8 bit pixel image 2004 VIDERE DESIGN Format Frame Frame Frame size rate 60 Hz rate 0 default Hz option Format 0 Mode 3 640x480 YUV 16 bits Left image on Y right image on UV Format 2 Mode 0 1280x960 3 75 7 5 Hz 3 125 YUV 16 bits 6 25 Hz Left image on Y right image on UV Table 1 Frame formats and sizes for the STH MDCS2 C On the host computer the SVS interface software takes the YUV stream and parses it into the left and right images making them available as separate images in computer memory It also performs color processing for the STH MDCS2 C converting the Bayer pattern into full color RGB images Smaller frame sizes are also available using on host binning Binning averages neighboring pixels to produce a smaller image with improved noise characteristics The STH MDCS2 also has a subwindow mode in which only the center portion of the image is returned See Section 7 4 for full information on the modes and resolutions for the STH MDCS2 3 3 50 Hz Operation Indoor lighting especially from
13. MDCS2 C uses standard C mount lenses for user changeable optics Wide angle to telephoto options are available depending on the application The variable baseline version of the STH MDCS2 C uses the same imagers but has a separate IEEE 1394 interface for each imager It has similar characteristics to the STH MDCS2 C please see the STH MDCS2 VAR C manual for more information SRI s Small Vision System SVS software has an interface to the STH MDCS2 C and is included with each stereo head You can simply and automatically calibrate the stereo head perform stereo correlation and view the results as a 3D point set The SVS software includes software drivers for the STH MDCS2 C for MS Windows 98SE ME 2000 XP and for Linux 2 4 and 2 6 kernels 02004 VIDERE DESIGN 1 1 Characteristics e Micron MT9M001 Megapixel Sensors 1280 x 960 maximum image size High sensitivity low noise Low pixel cross talk Rolling shutter e Fully synchronized stereo left and right pixels are interleaved in the video stream e Monochrome or Bayer Color e High frame rates 30 Hz for 640x480 7 5 Hz for 1280x960 e On chip decimation full frame 640x480 and 320x240 modes e Electronic zoom mode center 640x480 subwindow e Extensive control of video parameters Automatic or manual control of exposure and gain Automatic control of black level Manual control of color balance e50 Hz mode reduces indoor light interference in countries
14. PCs have either a built in IEEE 1394 port or a plug in PC Card sometimes called a PCMCIA card with several IEEE 1394 ports In both cases the laptop does not supply power to the IEEE 1394 bus and a source of external power must be used see below External power to the IEEE 1394 bus must have the following characteristics 7 to 16 VDC lt 1 5 W The IEEE 1394 spec allows up to 40 VDC on the bus but in practice many devices such as PC Cards will fail if a voltage higher than 16 VDC or so is used We recommend using a 12 VDC source Power can be supplied to the bus through an IEEE 1394 hub or PC Card with an external port Most hubs have such a port most PC Cards do not The PC Card supplied by Videre has a power port The format of the power plug can vary with the hub or PC Card so please check the specifications for the device Generally the positive terminal of the plug is on the inside and the negative is the outside cylinder STH MDCS2 USER S MANUAL 02004 VIDERE DESIGN Figure 5 1 shows the two configurations for supplying power A wall transformer converts line voltage to 12 VDC and is plugged into a hub or the PC Card PC Card with IEEE 1394 hub power port IEEE 1594 with power port IEEE 1394 Cable Cable IEEE 1394 Cable to PC L L Power Power 12 VDC gt 150 12 VDC gt 150 Figure 5 1 External power supply connections On the left is power supplied to a PC Card with a power port On the right
15. STH MDCS2 USER S MANUAL 2004 VIDERE DESIGN STH MDCS2 C Stereo Head User s Manual November 2004 2004 Videre Design STH MDCS2 USER S MANUAL Table of Contents J 0 ud eoe Dese EA E a Oa a 4 1 1 CAPA CCST SU CS NR EE TED EE E TNT 4 2 Ouud iue RR TU Tt 5 3 H rdware OVeEvVIe Wii ces dee pee ooa aces o Ces cipue teo cs e Oed oes aeo ideae 7 3 Hardware SCHEMA C 22 itte trate owe ote menus bee ve ba vt deset sten ts Vien 7 3 2 tame Forna and Rates osi a eave rebedensien uen uico J 3 3 SOUT OME AON a m Uu ts 8 Sk NTultple DeVIGe Sas pe A aah preste dot hace 9 4 Installing the 1394 Host Card and Capture Software 10 4 1 1394 Hardware and 10 4 1 1 MS Windows Hardware Installation 10 4 1 2 Linux Hardware and Driver Installation 10 4 2 STTEMDCS2 SODLDWAEO ueteri oo 10 5 12 5 IEEE 1394 ale uscire ceotes A Dose aio nde E doas tie teat 12 3 2 DEBE 368 divenuto Eta codi Aleta ncaa N 12 5 3 POWER IINE E 12 EE E OUR 14 6 1 L ockine Jens eS ioo iadeeot E N tte minit an 14 6 2 C and CS Mount 1 eese Preterea ore Dee ner ep RR eR 14 6 3 Chaneme 14 Ox Cleamins the Iria cers a a cacscwen yaivial ob nS up Slanamesaaie 14 6 5 tds eT 0 tea Sane 14 6 6 FNO d 20 219 09 95 davacssven aw ee Qna coto ea az Ee Ph cope atoveo dele duc oie ose eh 14 6 7
16. ation package for calibrating a stereo rig Use this application to perform calibration on your stereo system stcap exe isa simple application that connects to the stereo head and displays images It can serve as a template for user programs that integrate stereo capture from the STH MDCS2 C stdisp exe is a simple application that connects to the stereo head grabs images and performs stereo analysis and displays the results It can serve as a template for user programs that integrate stereo capture and computation from the STH MDCS2 C STH MDCS2 USER S MANUAL 5 IEEE 1394 Interface Digital image information is transferred from the STH MDCS2 C to the host PC via a 1394 cable The cable sends a video stream from the imagers to the PC and sends commands from the PC to the stereo head to control exposure subsampling etc The cable also supplies power to the stereo head 5 1 IEEE 1394 Cable The STH MDCS2 C must be connected to the host PC via a 6 pin male male IEEE 1394 cable The maximum length for such a cable is 4 5 m about 15 feet The cable supplies both signals and power to the stereo head The port on the STH MDCS2 is recessed so that the IEEE 1394 cable plug will not stick out from the camera The distance between the stereo head and the PC can be extended by using a 1394 repeater Several 1394 enabled devices can be connected together as long as the connection topology doesn t have any loops The STH MDCS2 C
17. ces 15 17 Figure 7 2 Frame size and sampling controls esses 18 Figure 7 3 Firmware parameters dialog c c ccessssessssseseeeeeeeeeeeeeenees 20 Table 1 Frame formats and sizes for the STH MDCS2 C 8 Table 2 Bus bandwidth requirements at different frame rates 9 Table 3 Horizontal and vertical field of view eeeeesssesesss 16 Table 4 Subsampling modes and frame rates 0 7 19 02004 VIDERE DESIGN STH MDCS2 USER S MANUAL 1 Introduction The STH MDCS2 is a revision of the STH MDCS digital stereo camera It is a compact low power digital stereo head with an IEEE 1394 digital interface It consists of two 1 3 megapixel progressive scan CMOS imagers mounted in a rigid body and a 1394 peripheral interface module joined in an integral unit The CMOS imagers are an upgrade from those in the STH MDCS They are MT9MOOI sensors from Micron Semiconductor They are 2 format with a resolution of 1280 H by 1024 V pixels and come in either monochrome STH MDCS2 or colorized STH MDCS2 C versions These imagers have excellent dynamic range sensitivity anti blooming and noise characteristics They are fully controllable via the 1394 interface the user can set exposure gain decimation etc They have better noise sensitivity and crosstalk characteristics than the previous sensors The STH
18. controls in the video capture program Both manual and automatic modes are available for the STH MDCS2 C devices In manual mode the user program sets the exposure and gain The exposure and gain are based on a 0 to 100 scale Here are some tips for setting exposure and gain e In general keep the gain as low as possible since it introduces additional noise into the system Use it only if the exposure is set to maximum or if the exposure must be kept low to minimize motion blur Indoors the gain is usually set higher because of the lower light levels e Adjust the manual iris of the lens to as small an opening as possible for your application without having to use gain This will increase the depth of field and give better optical performance Indoors the iris usually is fully open Outdoors in bright conditions the iris can be partially closed 2004 VIDERE DESIGN There are automatic modes for both exposure and gain In auto mode gain and exposure are controlled by the host PC which samples the incoming image and sends commands to the stereo device The auto algorithm will try to reduce gain as much as possible while still maintaining overall light levels in the image Auto mode for gain and exposure can be set separately For the STH MDCS2 it is recommended to use a manual mode for gain and auto mode for exposure Indoors set the gain to a higher value outdoors set it to a low value With exposure in auto mode the
19. dialog 20 2004 VIDERE DESIGN fixed in the firmware The one changeable parameter is for 50 Hz or 60 Hz operation Section 3 3 The Firmware Parameter dialog is only available after the STH MDCS2 has been opened by pulling down the Video item of the Input chooser To use 50 Hz operation check the box and then press the Save button This choice is downloaded and stored in the device and will cause 50 Hz operation every time the STH MDCS2 is accessed To change back to 60 Hz uncheck the box and again save it to the device It is also possible to clear any calibration parameters that are saved on the STH MDCS firmware If the calibration parameters are present the Clear Calibration button will be activated Pressing this button will clear the parameters See the SVS Users Manual for information on saving and loading calibration parameters on the device STH MDCS2 USER S MANUAL 02004 VIDERE DESIGN 8 Interface Software API Please see the Small Vision System manual for information about the software API for capturing and saving images 2 STH MDCS2 USER S MANUAL 02004 VIDERE DESIGN C The larger hole is threaded for a 14 20 machine screw standard tripod mounting screw The two smaller holes are threaded for 6 32 machine 9 Physical Dimensions and Mounting Screws Diagram The diagram below shows the physical dimensions for the STH MDCS2 AM videra Deaan 50 999 6708 Fax 0 646 STH ip 5 REV 4 Delrin and
20. dow has the effect of zooming the image by a factor of 2 Figure 7 2 shows the frame size and subsampling controls on the video capture application With SVS version 3 2b the sampling control has been changed to a simple Frame Division control For the STH MDCS2 there are two possible values 1 full image and 1 2 Refer to Table 4 for a complete list of allowed modes and how the frame size and sampling setting affect the output image Explicit control over the sampling mode is accomplished with the SetSample function from the SVS API The first four lines of the table are for full frame images At 1280x960 the full image is sent to the host PC and there is no binning At 640x480 there are two choices decimation on the imager or binning on the host the default is decimation on the imager Using SetSample 2 1 means that decimation will take place on the imager which then transmits a 640x480 imager this is the default for full frame images Using SetSample 1 2 means that binning will take place on the host In this case the imager transmits all 1280x960 pixels so the maximum frame rate is lower This is the greyed out line in the table 19 02004 VIDERE DESIGN For 320x240 binning will take place on the host PC and the imager The imager will transmit a 640x480 image and the host will bin that down to 320x240 The subsampling must be set with Set Sample 1 2 For 1 2 frame rates there are two resolutions 640x4
21. e will usually eliminate this vignetting 6 6 F Number The F number is a measure of the light gathering ability of a lens The lower the F number the better it is at pulling in light and the better the STH MDCS2 will see in low illumination settings For indoor work an F number of 1 8 is acceptable and 1 4 1s even better For outdoors higher F numbers are fine In any case it is useful to have a manual iris for high light situations While the imagers can have electronic exposure and gain control to automatically compensate for different light conditions the STH MDCS2 USER S MANUAL iix Figure No 1 File Edit Window Help Range Resolufion for Three Different Lenses 120 100 80 60 40 Range Resolution mm 20 0 1 2 3 4 5 6 7 8 9 10 Distance to Object m Figure 6 1 Range resolution in mm as a function of distance for several different lens focal lengths acceptable illumination range can be extended by mechanical adjustment of the lens opening 6 7 Focal Length The focal length is the distance from the lens virtual viewpoint to the imager It defines how large an angle the imager views through the lens The focal length is a primary determinant of the performance of a stereo system It affects two important aspects of the stereo system how wide a field of view the system can see and how good the range resolution of the stereo is Unfortunately there s a tradeoff here A wide angle lens short
22. ers dialog For a particular lighting source try adjusting the gains until a white area in the scene looks white without any color bias 7 2 Gamma Correction To display properly for human viewing most video images are formatted to have a nonlinear relationship between the intensity of light at a pixel and the value of the video signal The nonlinear function compensates for loss of definition in low light areas Typically the function is x where y is 0 45 and the signal is called gamma corrected Digital cameras such as the STH MDCS2 USER S MANUAL STH MDCS2 C do not necessarily have gamma correction This is not a problem for stereo processing but does cause the display to look very dark in low light areas You can add gamma correction to the displayed image by choosing an appropriate gamma value in the slider under the right display window Figure 7 2 73 Video Digitization Parameters The CMOS imagers have electronic exposure and gain controls to compensate for varying lighting conditions The exposure can vary from a maximum of a full frame time to a minimum of one line time Gain is an additional amplification of the video signal for low light situations It is settable from 0 to 18 dB 1x to 8x Both imagers are treated in exactly the same manner It is not possible to set a different exposure or gain on each imager Digitization control can operate in either manual or automatic mode Refer to Figure 7 1 for the
23. fluorescent fixtures can oscillate at the frequency of the electrical supply If the image frame rate does not divide evenly into this frequency there can be moving horizontal bands of alternating light and dark moving in the output For countries with 60 Hz power such as the United State the frame rates of Table 1 are ideal In many other countries the electrical line frequency is 50 Hz For these countries there is a mode to change the frame rates of the STH MDCS2 USER S MANUAL STH MDCS2 to sub multiples of 50 Hz These frame rates are shown in the last column of Table 1 The frame rate mode of the STH MDCS2 device can be changed by using the Firmware Parameter dialog see Section 7 6 3 4 Multiple Devices Multiple STH MDCS2 devices can be attached to the same IEEE 1394 bus When streaming video at the same frame rate they are synchronized so that they capture images at the same time Each IEEE 1394 PC Card or PCI Card defines a separate IEEE 1394 bus The two or three ports on the card all belong to the same bus as does any IEEE 1394 hub connected to these ports Separate PC Cards and PCI Cards cannot be connected to each other The number of devices that can simultaneously send video is determined by the maximum bandwidth of the bus for isochronous transfers 32 MB s This rate cannot be exceeded by the combined video streams on the bus Table 2 shows the bandwidth requirements for the STH MDCS2 in various modes and for
24. focal length gives a great field of view but causes a drop in range resolution A telephoto lens long focal length can only see a small field of view but gives better range resolution So the choice of lens focal length usually involves a compromise In typical situations one usually chooses 15 2004 VIDERE DESIGN the focal length based on the narrowest field of view acceptable for an application and then takes whatever range resolution comes with it 6 8 Range Resolution Range resolution is the minimum distance the stereo system can distinguish Since stereo is a triangulation operation the range resolution gets worse with increasing distance from the stereo head The relationship is 2 Ar 2 Ad bf where b is the baseline between the imagers f is the focal length of the lens and Ad is the smallest disparity the stereo system can detect For the STH MDCS2 C b is 90 mm and Ad is 0 325 um pixel size of 5 2 um divided by the interpolation factor of 16 Table 3 plots this relationship for several focal lengths At any distance the range resolution is inversely proportional to the focal length 6 9 Field of View The field of view is completely determined by the focal length The formulas for the FOV in horizontal and vertical directions are HFOV 2arctan 3 33 f VFOV 2arctan 2 50 f where f is in millimeters For example a 3 5 mm lens yields a horizontal FOV of 87 degrees This is about the smallest
25. ges can be de warped just like the monochrome images to take into account lens distortion see the Small Vision System User s Manual Color information from the camera is input only if the Color button is pressed on the main window Figure 2 1 Because the typical color camera uses a colorizing filter on top of its pixels the color information is sampled at a lower resolution than a similar non colorized camera samples monochrome information In general a color camera has about 1 4 the spatial resolution of a similar monochrome camera The cameras have on imager binning from 1280x960 to 640x480 Whenever the 640x480 frame size is requested binning is automatically performed on camera and all the pixels are used For 320x240 frame sizes binning is performed by the SVS software The relative amounts of the three colors red green blue affects the appearance of the color image Many color CCD imagers have attached processors that automatically balance the offsets among these colors to produce an image that is overall neutral called white balance The STH MDCS2 C provides manual color balance by allowing variable gain on the red and blue pixels relative to the green pixels Manual balance is useful in many machine vision applications because automatic white balance continuously changes the relative amount of color in the image The manual gain on red and blue pixels is adjusted using the Red and Blue controls on the Video Paramet
26. here is an IR cutoff filter with a knee at approximately 680 nm permanently mounted inside the lens holder See Section 6 for appropriate lens characteristics The interface module is mounted on the back of the stereo head One IEEE 1394 port is placed at the back of the module it is inset so that the IEEE 1394 plug does not stick out from the device A status LED indicates video imager activity It will turn on when the device is powered and connected to an IEEE 1394 card on the host computer The LED will begin flashing as soon as images are being acquired by the host computer at 72 the frame rate Changing the video modes frame size decimation will cause the frame rate to change and this will be reflected in the LED flash rate IEEE 1394 Right port on back C CS mount lens Left C CS mount lens indicator Figure 3 1 Physical layout of the STH MDCS2 C stereo head 2004 VIDERE DESIGN There are no user settable switches on the STH MDCS2 C 3 1 Hardware Schematic Figure 3 2 shows the design of the internal hardware of the STH MDCS2 C In the stereo imager module two CMOS imagers each of size 1280 x 1024 pixels digitize incoming light into a digital stream The imagers operate in progressive mode only that is each line is output in succession from the full frame The maximum video rate is 12 megapixels per second from each imager The imagers are synchronized to a common clock so that the corresp
27. mation text when the capture application is started It should say DCS digital stereo interface If not the wrong interface library is installed in Svsgrab dllorlibsvscap so The directory structure for the software is Diti smallv exe smallvcal exe smallvmat exe svsgrab dll lib libsvscap so interface libraries stereo calculation libraries src flwin cpp image_io cpp 2 svsclass h svs h flwin h samples smallv cpp fldispx cpp dsw dsp makefile There are several applications see the SVS User s Manual for more information The source code for all applications is included in the distribution The stereo calculation libraries are also included so that user applications can link to them The calibration libraries are not included the 1 2004 VIDERE DESIGN only way to run the SVS calibration procedures is through the smallvcal exe application smallv exe is a GUI based application that allows the user to exercise the capture and stereo functions of the STH MDCS2 C It is described in earlier sections of this document smallvmat exe is similar to smallv with the addition of a MatLab interface for sending images and stereo information to MatLab You must have installed the R13 release of MatLab to run this program There is also a version of SVS that can be invoked directly from MatLab again see the SVS User s Manual smallvcal exe is the same as smallv with the addition of a calibr
28. onding pixels from each imager are output at precisely the same time Special interlace electronics convert the individual streams into a single pixel interlaced stream at 24 MHz The interlaced stream contains one byte from the left imager then the corresponding byte from the right imager then the next byte from the right imager and so on The interlaced video stream is transferred to the IEEE 1394 interface module which communicates to the host PC over an IEEE 1394 digital cable The module also accepts commands from the host PC over the cable and uses these commands to control imaging modes such as exposure or subwindowing The IEEE 1394 interface module can communicate at the maximum IEEE 1394 data rate 400 MBps 3 2 Frame Formats and Rates The IEEE 1394 interface electronics on the STH MDCS2 supports a maximum rate of 24 megapixels per second At this rate there is no need for large buffer memories to hold video data on the stereo device The STH MDCS2 C conforms to the HDC version 1 30 camera specification Frame rates and frame sizes are set by this standard The STH MDS C implements the formats shown in Table 1 The Digital Camera Specification was set up with monocular cameras in mind To conform to this specification the STH MDS C uses the YUV STH MDCS2 USER S MANUAL 8 bit pixels 12 MHz per imager Imager module Interlace Electronics 1394 Interlaced imaging pixels commands 24 MHz 1394 13
29. ot as reliable 4 2 STH MDCS2 Software The STH MDCS2 C comes with the SVS stereo software and several sample applications including the GUI application described in this manual For the most up to date information about installation please see the Videre Design website www videredesign com support svsmsw htm To install the software under MS Windows execute the file svSXXX exe If you have installed a previous version of SVS the installation wizard will ask you if you want to un install the old version It is best to uninstall the old version then start the installation file again and install the new one The installation process will add the relevant interface and application software To install the software under Linux untar the file svsXXX tgz in a new directory which will become the top level directory of the software You should also set the environment variable SVSDIR to this directory and add bin to your LD LIBRARY PATH variable libsvscap so and svsgrab lib dll are the capture libraries for Linux and MS Windows respectively These libraries must be set to the correct ones for the STH MDCS2 STH MDCS2 USER S MANUAL In MSW Windows execute the file bin setup dcs bat This will copy svsdcs d11 1ib as the interface libraries Under Linux copy the following file in the bin directory dcscap so gt libsvscap so Linux You can check that the correct interface library is installed by looking at the infor
30. power is supplied through a hub with a power port Power should be 7 to 16 VDC at gt 1 5 W Check the PC Card or hub for the type of power connector 13 STH MDCS2 USER S MANUAL 6 Lenses The STH MDCS2 C uses standard C or CS mount lenses Good quality fixed focus lenses with low distortion and high light gathering capability are best Lenses are characterized optically by imager size F number and focal length Following subsections discuss the choice of these values 6 1 Locking Lenses Some lenses come with thumbscrew locks for holding the focus and iris settings We recommend these locking lenses for all applications in which the device is moving or in which people or objects may touch the lens Locking lenses are available from Videre 62 Cand CS Mount Lenses The STH MDCS2 will accommodate either C or CS mount lenses CS mount lenses have a mounting distance of 12 5 mm from the imager C mount lenses have a mounting distance of 17 5 mm Normally 1 2 format lenses are of the C mount variety They require a 5 mm spacer to focus properly This spacer is shipped with the STH MDCS2 it is the round silver part on the lens holder To use CS mount lenses unscrew the spacer before mounting the lens 6 3 Changing Lenses Standard C CS mount lenses have a 1 diameter 28 threads per inch screw on their back end The screw mates with the lens holder opening To insert a lens place its back end on the lens holder opening as st
31. raight as possible and gently turn it clockwise looking down at the lens until it engages the threads of the lens holder If you encounter a lot of resistance you may be cross threading the lens Forcing it on will damage the lens holder or lens threads 14 2004 VIDERE DESIGN Once the threads are engaged continue screwing it on until it seats firmly You can snug it down but do not tighten it excessively since this can damage the lens and the lens holder threads Removing the lens is the reverse process unscrew the lens counter clockwise There will be some initial resistance and then it should unscrew smoothly Normal care should be used in taking care of the lenses as with lenses for any good quality camera 6 4 Cleaning the Imagers It should not be necessary to clean the imagers since they are sealed off by an IR filter inside the lens mount If dirt and dust are present on the IR filter surface they can be cleaned in the same manner as a lens Wet a non abrasive optic cleaning tissue with a small amount of methyl alcohol or similar lens cleaning solvent and wipe the imager glass surface gently Dry with a similar tissue 6 5 Imager Size The imager size is the largest size of imager that can be covered by the lens For the STH MDCS2 the lens must be 1 2 or greater For some wide angle lenses there will be a little vignetting darkening on the corners of the image Calibration and rectification of the imag
32. there is a problem with the IEEE 1394 drivers please see Section 4 If the images are too light or too dark you can open the manual iris of the cameras or change the exposure and gain settings W SRI Smallv Stereo System Joj x Fie Device Wideo Video Buffer byvindow librate Debug Rate 0 0 T Left F Color 55 version 3 08 DCS Digital Stereo Interface Right Color 1 00 Gamma Input None Function None gt Cont 32 H Disparity 0 Size noe v 3D Displa MMX Horopter Window qu Sample none Swap fart X off ao H LAR Check Rate 15 v l Color Capable F Multi Scale Figure 2 1 SVS main program window STH MDCS2 USER S MANUAL Section 7 3 Images can be saved using the File menu A more complete description of the video capture program is in Section 7 The SVS programs are described in the SVS User s Manual and the SVS Calibration Addendum documentation that comes with that software It 1s helpful to review Section 7 in conjunction with the SVS documentation 02004 VIDERE DESIGN STH MDCS2 USER S MANUAL 3 Hardware Overview Figure 3 1 shows the hardware configuration of the STH MDCS2 C The imager module has a milled aluminum alloy frame that rigidly holds two megapixel imagers separated by a fixed distance of 9 cm Lens mounts are an integral part of the frame and standard C or CS mount lenses are screwed into these holders T
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