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Eye-Head Integration

1. 4 1 Eye Tracker Subject Calibration Apply the Head Mounted Optics to the subject as described in the HMO Manuals and Training Guides Ensure proper discrimination on the Pupil and Corneal Reflection Remember that the subject s head must remain within the tracking range of the Head Tracker in order for EHI to function properly The subject s head need not remain stationary for the calibration process to be successful however increased accuracy will be experienced when there 1s fairly limited head motion The Calibration procedure for EyeHead Integration is the same procedure used for other types of Eye Tracking methods The system uses the 9 Calibration Points of Scene Plane 0 for its calibration 4 1 1 Calibration Procedure Calibrate E Standard Calibration Selecting Standard Calibration Quick Calibration Custom Quick Calibration Calibration Prepare Auto Calibration or Start Auto Custom Calibration Calibration will open the Eye Tracker Calibration window es Prepare Auto Calibration in the appropriate mode From the Eye Tracker Genitalia Pulte Eel n Calibration window you can also change the calibration Start Auto Calibration type to any of these modes by way of the Calibration Type item 17 EYEHEAD INTEGRATION MANUAL The currently active calibration point that which the system 1s waiting for a calibration about is displayed in the Calibration Point item The currently active point can be changed with the arrows o
2. See Section 3 2 4 Stationary lees pnm Scene Camera oo Point3 Y o zs o Point4 Y o z o Enter the y horizontal and z vertical coordinates foreachof 770 5 m the 5 SSC points previously discussed The coordinates are specified in the coordinate frame assigned to the scene plane as discussed in Section 3 EyeHead Environment Specification Check the box labeled enable If this box is not checked the system will not attempt to display a stationary scene camera cursor when a subject looks at this scene plane If a scene plane is not visible on the stationary scene camera video image then this enabling check box should always be off If the scene plane is visible or partially visible and will be part of the stationary scene camera environment turn the check box on Restore Defaults Cancel To repeat the procedure for another scene plane click the Next button or the down arrow on the scene plane dialog box and select desired plane 6 2 3 Enter Scene Camera Locations of SSC Points After the Scene Plane coordinates are set for each of the SSC Points See Section 6 2 2 Enter Scene Plane Locations of SSC Points the Point s locations must be specified with respect to the Scene Camera image The SSC point locations on the stationary scene camera image are entered by clicking on scene monitor images of these points with a mouse controlled cursor It is very similar to the Set Target Points pro
3. cience Laborxytarirer 1 Introduction The EyeHead Integration package for use with head mounted eye trackers enables integration of eye and head position data to compute point of gaze Point of gaze is computed with respect to a room fixed or cockpit fixed scene space The scene space is defined by a set of planes consisting of one calibration plane and a variable number of additional bounded planes If the Stationary Scene Camera SSC option is included then point of gaze in the environment can be superimposed on the image from a stationary as opposed to head mounted video camera The required hardware includes a head mounted eye tracker eg Model H6 with Head Tracking HT option an HT Transmitter mount and a pointing device Gimbal Laser or Sensor Wand Required software is the standard ASL User Interface software with EyeHead Integration option EHI All of the above additions to the basic eye tracker system are included in the EyeHead option package from ASL The stationary scene camera mentioned above and the scan converter are additional options available for the system that serve to bring in a video representation of the tracking environment The HT electronics unit is normally plugged into a serial port labeled HEAD TRACKER on the model 6000 eye tracker control unit Integrated Eye Head data can be output in real time through another serial port labeled SERIAL OUT or recorded on the Eye Tracker Interface PC Th
4. gt ralon hox bct i te phle The system is usually shipped from ASL with the transmitter already installed in a mounting tuppeart poe assembly consisting of a back plate that can be hpo marerittet fastened to a mounting surface a bottom plate a top plate and two support posts that extend mrs eT between the top and bottom plates If transmitter is not already installed in this assembly 1 Fasten the top plate bottom plate and support bracket to the back plate with screws provided 2 Insert the transmitter between the two plates with its mounting base against the bottom plate and the cord extending towards the back plate 3 Fasten the two support posts between the top and bottom plates with nylon screws provided 4 Using the provided nylon bolts and hex key bolt the transmitter mounting holes to the bottom plate Note that the hex key must be inserted though the access holes provided in the top plate Mount the back plate to stable non metallic surface using the mounting holes in the back plate Metal screws can be used here if needed It is suggested that the assembly be mounted so that the transmitter will be behind and slightly above the subject s head When the subject 1s wearing the helmet with magnetic sensor attached and is in the nominal center position the sensor should be about 5 10 inches from the transmitter It is suggested that the transmitter be roughly straight and level with the x axis pointin
5. 1 Opening a New Data File 20 5 2 Starting and Stopping Recording 20 5 3 Close Data File 21 6 Stationary Scene Camera Optional 22 6 1 Scene Camera Installation 22 6 1 1 Optical Camera 22 6 1 2 Scan Converter 23 6 2 Stationary Scene Camera Software Configuration 23 6 2 1 Attaching Scene Planes to the Video 23 6 2 2 Enter Scene Plane Locations of SSC Points 25 6 2 3 Enter Scene Camera Locations of SSC Points 25 6 2 4 Check SSC Environment Specification 26 EYEHEAD INTEGRATION 6 3 Using SSC during Real Time Eye Head Integration 7 Serial Output Interface 7 1 Interface Cable 7 2 Protocol and data format 7 3 Serial Port Configuration 7 3 1 Streaming Mode 7 3 2 EyeHead Integration Mode 8 Head Trackers 9 Transmitter Mount amp Laser Gimbal Assembly 9 1 Transmitter Mount amp Gimbal for Ascension Flock of Birds 9 2 Transmitter Mount amp Gimbal for Polhemus 3 Space or Isotrak 9 3 Laser Pointer Assembly 9 4 Laser Pointer 10 Analysis 11 Appendices 11 1 Measuring the Sensor to Eye Vector 11 1 1 Measurement Estimation with a Ruler Case Evelrackitdg Expvertise A Applied cience Laboratories 27 28 28 28 30 30 31 32 34 34 36 38 39 41 42 42 42 EYEHEAD INTEGRATION m ASL Eyelrackicey Expirtizx Applied chence Laboratarier 11 1 2 Measurement using Magnetic Tracker Data 42 EYEHEAD INTEGRATION MANUAL a ASL Eyelracki Expiertizz Apnlled
6. Higher camera speeds 120 240 360Hz will cause the eye tracker to send more data packets per second If Streaming Mode is not checked eye tracker is in On Demand mode which means it will send data upon request by the receiving computer s application Most applications will require Streaming Mode Please refer to the user s manual for your receiving software to determine the appropriate transmission format 30 EYEHEAD INTEGRATION MANUAL in ASL Eyebrackicny Expertise Apnlled Scher Laborsehorker 7 3 2 EyeHead Integration Mode These tabs select between Serial Out format elements available for EyeHead Integration or standard eye tracker modes In the EyeHead Integration tab select the appropriate elements to output over the Serial Out port The items will be output in the order of top to bottom on the table The number in parentheses denotes the number of data bytes output by that selection Total message size indicates the total number of bytes that is transmitted during each output sample the length of the word being sent 31 EYEHEAD IMTEGRATION MANUAL a ASL Eyelracki Expiertizz Applied science Laborxrtarirr 8 Head Trackers The Head Tracker HT unit comes individually packaged The package contains a control box a source module Transmitter with cable and connector a sensor module Receiver with cable and connector and a manual with one or more floppy disks The HT system is usually either
7. It allows for specifying surfaces of greater distances e Place sensor directly on points With this method the operator places the HT Sensor directly on the surface points All points must be within the range of the Transmitter s operational field This method is not recommended e Manual entry With this method the operator types the aa e spatial coordinates into the system manually dr S e Point with sensor wand The sensor wand is a freely moving rod One end contains a cup for placing the HT Sensor while the other head has a pointed tip for placing on the surface points With this method the operator places the tip of the wand on the appropriate surface points This allows for easy specification of points that are relatively near or medium distances from the Transmitter EYEHEAD INTEGRATION MANUAL ASL Evabuckeng Experian Apnlled science Laborxrtarire The sensor end of the wand must remain within the range of the Transmitter s operational field e Point with inverted gimbal laser This option is designed to be used in special situations when the HT Sensor is mounted on the rear portion of a special gimbal assembly on the opposite side from the laser pointer This is intended specifically for specific rare situations involving the Ascension Laserbird headtracker 3 2 3 4 Distance from Head Tracker Origin to End of Laser Availability Point with Laser Gimbal method selected If using the Laser Gimb
8. This check is easily accomplished with the Pointer Test procedure This procedure is most conveniently done with two people 13 EYEHEAD INTEGRATION MANUAL 5p ASL Eyebrackicey Expirtizz Apnlled science Laborvtarirr 3 5 1 Pointer Test The Pointer Test uses the mechanism used to define the Scene Plane surfaces Laser Gimbal or EHI Sensor Wand to mimic a gaze vector for testing purposes This allows the user to test the accuracy of the system definitions and Head Tracker calculations without adding the extra variability of a subject Eye Tracker calibration 1 2 3 Select the Pointer Test from the EyeHead pull EyeHead QM down menu or click the associated 1con on the Pointer Test Mode TEST shortcut bar The software will prompt you to aim the pointer at Calibration Point 5 i X Hold the Pointer so that the laser spot or the tip Hit OK when pointing at point 5 of the Sensor Wand is centered on Calibration Point 5 center calibration point on Scene Plane 0 and click OK while the pointer is stable Continue to hold the pointer on point 5 until the pop up window disappears Check the environment Direct the Pointer to point at known coordinates on each scene plane while checking the EyeHead grid pattern display In the Pointer Test mode the gaze vector is assumed to be aligned with the pointer The POG Indicator cross on the grid pattern display should correctly indicate the position of the pointer This
9. angle lens with significant barrel distortion is used there may be errors in cursor superposition roughly equivalent to the distortion If the subject is looking at a video image the same video signal can be used directly to mimic the function of a Stationary Scene Camera image showing a single surface Similarly if the subject 1s looking at a computer monitor VGA image a Scan Converter can be used to create a corresponding video signal that can be used directly to mimic a Stationary Scene Camera image showing a single surface Note that a camera can be aimed to encompass several surfaces for example two side by side computer screens and a keyboard whereas the Scan Converter signal or direct video signal will contain the image of only one surface If there is only one surface of significant interest and its image is available from a scan converter or other video source then use of this signal 1s the best approach 6 1 Scene Camera Installation 6 1 1 Optical Camera If the scene image is to be captured using a camera aim the Stationary Scene Camera so that it captures the field of interest This may include part of one scene plane an entire scene plane or several scene planes Try to orient the camera so that the horizontal axes of scene planes viewed by the SSC do not appear tilted greater than approximately 45 degrees with respect to the scene monitor horizontal axis Attempt to make the scene plane of most significant interest app
10. assembly rear plate from the rest of the mounting assembly 2 Fasten the rear plate to a stable nonmetallic surface using the four countersunk holes and the screws provided 3 Reattach the rest of the assembly to the rear plate The transmitter should be fastened to the top plate transmitter mounting surface facing up and the cord should extend towards the mounting surface 4 Two clips are provided which can be fastened to the mounting surface just below the source mount assembly and can be used to strain relieve the wire If the transmitter mount is not assembled when shipped proceed as follows 1 Fasten the rear plate to a stable nonmetallic surface using the four countersunk holes and the screws provided 2 Attach the top and side pieces of the mount assembly to the rear piece using the provided nylon screws four 10 32 x 1 2 and two 10 32 x 1 3 Attach the magnetic source to the under surface of the mount top piece using three provided 10 32 x 1 screws The source should be mounted so that the wire exits towards the mounting surface at the rear of the mount assembly 4 Attach the small bottom piece of the mount assembly to the side pieces using four of the provided 10 32 x 1 2 screws Be sure that the countersunk hole faces down and the edge with a curved radius faces front away from the mounting surface 37 EYEHEAD IMTEGRATION MANUAL a ASL Eyebrackicey Expirtizz Apnlled Fcheroe Laborvrtarirer Locate th
11. axis from the center of the sensor to a point even with the eye Even with the eye means the point on the x axis from which a line perpendicular to the x axis would intersect the eye being monitored This will be the x value Repeat this for the y and z axes If you measure in the negative direction along any axis the corresponding coordinate value will be negative The process involves estimation because it will be impossible to place a ruler directly on the points being measured Aligning the ruler with the direction of a given axis will be estimation as well 11 1 2 Measurement using Magnetic Tracker Data Place the headgear with magnetic sensor attached on a Styrofoam or other non metal material model head Alternately use a wooden Q tip swab or other non metal object to mark the position of the eye when the headgear is worn by a subject For example it is usually possible to tape a Q tip swab to the helmet liner or headband forehead strap such that the white Q tip is near the 42 EYEHEAD IMTEGRATION MANUAL a ASL Eyebrackicey Expiertizz Apnlled cience Laborvtarirer usual eye location While a subject is wearing the headgear just note the position and length needed for the Q tip Tape it on once the headgear is removed Do not hold the Q tip near a person s eye Boot the system and support the headgear so that the magnetic system Az El and RI angles as displayed on the e5win scre
12. can be used for the SSC The most common types are a fixed video camera viewing the environment or a video image from a single computer screen intercepted and relayed via a Scan Converter In both cases the video is input into the system by way of the Remote Scene port on the back of the ASL Control Unit The output video is sent by way of the Scene Out port To set up a Stationary Scene Camera see Section 6 Stationary Scene Camera Optional and Section 3 2 4 Stationary Scene Camera 3 7 Environment Configuration Backup The system will always save the EyeHead EyeHead environment information to the default XML file and ge restore it on Eye Tracker start up The user can also RESdE a dtoR save environment information to a separate file by Save EveHead Configuration selecting the EyeHead menu command Save EyeHead Configuration Information from this user specified file can be restored later by executing the menu command Read EyeHead Configuration 15 EYEHEAD INTEGRATION MANUAL in ASL Eyebrackicny Expertise Apnlled cemoe Laborvtarirr 3 7 1 Save Environment File The environment configuration can be backed up and stored by saving it to a separate XML file This is done by using the EyeHead menu selection Save EyeHead Data An XML file saved under a different name can later be used for EyeHead Integration by using the Read EyeHead Configuration selection In this way multiple environment files can be
13. corners respectively point 3 near the center and points 4 and 5 near the lower left and right corners The points should cover most of the area visible on the SSC image of a particular plane In order to obtain a unique solution for the transform equations the points should be chosen so that there are 5 different vertical scene plane coordinate values and 5 different horizontal coordinate values In other words no two points should have the same horizontal or vertical coordinates Point 2 should not have exactly the same vertical coordinate as Point 1 in the scene plane coordinate system Point 5 should not have exactly the same vertical coordinate as Point 4 Point should not have exactly the same horizontal coordinate as Point 4 Point 2 should not have the same horizontal coordinate as Point 5 Again note that no two points are on the same horizontal or vertical grid line The sets of 5 points used to define the stationary scene camera environment will be referred to as stationary scene camera or SSC points 24 EYEHEAD INTEGRATION MANUAL C E ASL E Evabecking Expentien Apnlled cience Laborrtarirr 6 2 2 Enter Scene Plane Locations of SSC Points The spatial coordinates of the 5 Points must be defined for mem x each Scene Plane in terms of that Scene Plane s coordinate Grea caper ere esis SED ree system This is done in the EyeHead Setup window under the 7 oe K Ei Stationary Scene Camera tab
14. created and used interchangeably without going through the environment specification process each time Keep in mind that if the position of any of the surfaces or the Head Tracker Transmitter changes then these environmental configurations will be invalid 3 7 2 Reading Environment Files To read an environment configuration from an XML file select Read EyeHead Configuration from the EyeHead pull down menu Browse to the desired file and click Open The system will replace the EyeHead Configuration stored in the active file E6000 XML with the EyeHead Configuration from the loaded file 16 EYEHEAD INTEGRATION MANUAL Sp Casc Eyalracking Expertise Applied science Laborsehorker 4 Collecting Data with EyeHead Integration Be sure that the eye tracker 1s running and that the EysHead Head Tracker system is enabled and communicating i SEE b with the eye tracker See Section 8 Head Trackers With a valid EyeHead Environment configured See Section 3 EyeHead Environment Specification enable real time EyeHead Integration by selecting Activate EyeHead Integration from the EyeHead pull down menu or clicking the short cut icon The POG Display window will switch to EyeHead EYEHEAD Integration mode as described in Section 3 3 EyeHead Scene 0 Grid Pattern Display and the EyeHead Digital Data Magn 100 Frame will become active on the main interface bie ae pos 2 window See Section 3 4 The EyeHead Data Frame SCC OFF
15. eye in the sensor s coordinate system The appropriate values are listed for any helmet or headgear supplied by ASL If it is necessary the method by which these values are calculated can be found in Appendix Section 11 1 Measuring the Sensor to Eye Vector Although the eye may not be in exactly the same position between subjects the EHI process is insensitive to these small differences in the sensor to eye vector 3 2 2 Calibration Target Points Tab This tab sets the real world relational positions of the nine calibration target points One surface in an EyeHead environment must be designated as the Calibration Scene Plane also known as Scene Plane fame and Dire Saree and Come Feriene D nobts Cancel EYEHEAD INTEGRATION MANUAL 5p ASL Eyebrackicny Expertise Apnlled cemoe Laborvtarirr 0 This surface must be able to display the calibration target points as discussed in Section 4 1 Eye Tracker Subject Calibration The operator must measure and enter the relative horizontal and 4 vertical coordinates on that scene s surface Calibration Point 5 by convention is usually defined as 0 0 ux fum Horizontal Y values are positive to the right Vertical Z values are 0 0 positive down Therefore if the Point 5 defined as 0 0 convention is used Calibration Point 1 will usually be and Point 3 will usually be 4 3 2 2 1 Auto Set Using Points 1 and 9 This button will take the value
16. of view In other words the subject should be able to look at this surface straight on during calibration EYEHEAD INTEGRATION MANUAL ASL A coordinate frame must be assigned to the calibration surface as shown in the figure The coordinate frame y z axes must lie on the surface with y axis units increasing to the right and z axis units increasing from top to bottom The x axis is normal to the surface The y and z axes will often be referred to as horizontal and vertical axes respectively The nine target points must have known y z coordinates in this frame expressed in inches or centimeters It is strongly suggested although not required that eye calibration point 5 be at the origin of the calibration plane coordinate frame y 0 z 0 All other designated scene surfaces must also have an associated coordinate frame and must conform to the same guidelines as the calibration scene plane with the following exceptions 1 The associated coordinate frame s need not have its origin in the center of the plane although the real time display will place the scene plane s origin in the center of the screen The scene surface must still coincide with the y z plane of its coordinate frame 2 There is no restriction on the orientation of the planes whereas the calibration plane should be viewed straight on during calibration 3 Only the calibration plane need have nine eye calibration target points A rectangula
17. or equivalent video source see Section 6 Stationary Scene Camera Optional 3 3 EyeHead Grid Pattern Display When testing environment specifications or conducting EyeHead EUN Integration tracking data can be viewed in real time in the POG Display window on the main interface screen The POG Display window will change to EyeHead Mode displaying a calibrated grid as defined in the Real Time Graphics Grid Scale See Section 3 2 3 11 It will automatically appear when entering the Gimbal Test mode or EyeHead Integration mode but can also be toggled on and off with the Data Display selection on the EyeHead menu The EyeHead display 1s characterized by a grid pattern that covers the display window The center of the grid represents the origin of the current scene plane The nine calibration target points are displayed as small yellow circles on the grid pattern when the Calibration Scene Plane Scene Plane 0 is being displayed The space between grid lines represents the scene distance specified in the General Parameters window See Section 3 2 3 11 Real Time Graphics Grid Scale Red circles indicate the Points ABC that define the current Scene Plane surface See Section 3 2 3 Scene Planes Tab 12 EYEHEAD INTEGRATION MANUAL Se ASL Eyebrackicny Expirtinz Apnlled Fcheroe Laborvtarirr 3 4 The EyeHead Data Frame EYEHEAD So Scene This frame on the main interface window displays the digital values of R
18. requires additional configuration in order to properly superimpose the POG indicator on this feed 6 2 1 Attaching Scene Planes to the Video The SSC cursor can be correctly superimposed only on the video image of surfaces defined as EyeHead Scene Planes Each Scene Plane must be attached to the video signal as discussed below 23 EYEHEAD INTEGRATION MANUAL Regions in the video image that do not have a Scene Plane attached may not yield a completely accurate representation of the POG position Scene Planes that are not attached to a portion of the video field will not be represented by a POG indicator The known locations of 5 points on the Scene Plane surface will be defined in terms of their relative positions on the scene camera field This relationship will be used by the computer to determine a transformation from the Scene Plane to the Scene Camera coordinates For each Scene Plane that will be part of the SSC environment it is necessary to define the positions of 5 points on each Scene Plane surface All 5 points must be visible on the SSC video image and must have known physical coordinates within their respective Scene Plane coordinate systems See Section 3 EyeHead Environment Specification These points will be defined in the Stationary Scene Camera tab of the EyeHead Setup window See Section 3 2 4 Stationary Scene Camera The 5 points should form a pattern with points 1 and 2 near the upper left and upper right
19. the location of such surfaces consult ASL for details Before any EyeHead Integration can take place all of the scene planes flat surfaces of interest must be defined in the User Interface software within the EyeHead Setup dialog The environment data is saved in the XML system file and can be saved separately Various pieces of information are typed into the dialog windows by the user and some necessary vector direction information is generally provided by pointing the gimbal pointer device a pointing wand or holding the magnetic sensor directly on target points These procedures are described in the succeeding manual sections However before explaining the mechanics of entering environment information into the computer the rules and theory for preparation of the physical environment are discussed below The surfaces in the environment must consist of a xm calibration surface plane 0 and up to 20 al additional scene planes The calibration surface will contain 9 calibration target points for eye tracker calibration It should subtend at least 20 _ degrees visual angle during calibration so that 20 30 ios A calibration target points can be separated by at lis least 10 degrees Furthermore during the eye tracker calibration procedure it is best if the vector from the subject s eye to the center target point point 5 1s roughly normal perpendicular to the surface and point 5 1s roughly in the center of the subject s field
20. will contain a value for each Scene Plane defined in the Number of Scene Planes field on the General EHI Tab See Section 3 2 1 Every Scene Plane in the environment must be selected and have all of the parameters of this tab defined in order for EHI to function properly EYEHEAD INTEGRATION MANUAL Pe ASL Eyebrackicny Expertise Apnlled Feber Laborxrtarir 3 2 3 2 Make Transparent This selection causes the active Scene Plane to become transparent or invisible to the EyeHead environment If this is selected the system will not attribute any point of gaze calculations to this surface and will instead attribute them to any surfaces behind the transparent plane This 1s occasionally useful if the operator wishes to define surfaces that may not be present for all parts of a study 3 2 3 3 Options for Specifying Points A B C The method by which the EHI surfaces are defined must be selected Once a technique 1s chosen that method must be used for all EHI processes for the duration of the setup procedure e Point with gimbal laser The laser gimbal is a mounting for the HT Transmitter device that allows a laser pointer to swing freely around the central point of the Transmitter The HT Sensor is placed in a cup attached to the gimbal assembly With this measurement method the operator points the laser at the appropriate surface points and physically measures the distance from the end of the laser pointer to the surface point
21. EYEHEAD INTEGRATION xn ASL EyeHead Integration Manual FOR USE WITH THE EYETRAC 6 SERIES H6 HEAD MOUNTED OPTICS Evelrackiag Expertise Applied Fcherce Laboratarier MANUAL VERSION 1 03 11 July 2007 Flock aansci 175 Middlesex Turnpike Bedford MA 01730 USA Tel 781 275 4000 Fax 781 275 3388 Email asl 9 a s l com Support techsupport a s l com Web site www a s l com Applied Science Laboratories An Applied Science Group Company EYEHEAD INTEGRATION 2 ASL Eyeberack cry Expirtize Applied chence Laboratarirer Table of Contents 1 Introduction 1 2 Interface Software 2 3 EyeHead Environment Specification 3 3 1 Units 2 3 2 EyeHead Setup 5 3 2 1 General Tab 6 3 2 2 Calibration Target Points Tab 6 3 2 35 Scene Planes Tab 7 3 2 4 Stationary Scene Camera 11 3 3 EyeHead Grid Pattern Display 12 3 4 The EyeHead Data Frame 13 3 4 1 Scene 13 3 4 2 Magn 13 3 4 3 Vpos and Hpos 13 3 5 Checking environment specifications 13 3 5 1 Pointer Test 14 3 6 Stationary Scene Camera optional 15 3 7 Environment Configuration Backup 15 3 7 1 Save Environment File 16 EYEHEAD INTEGRATION ASL Eyeberack ice Expirtizx Applied chence Laboratarirer 3 7 2 Reading Environment Files 16 4 Collecting Data with EyeHead Integration 17 4 1 Eye Tracker Subject Calibration 17 4 1 1 Calibration Procedure 17 4 1 2 Understanding Calibration 18 4 2 Checking the Calibration 18 5 Data Recording 20 5
22. Selecting any of the tabs will bring up a window with items associated to that heading Uses of items within each tabbed EYEHEAD INTEGRATION MANUAL Sp ASL Eyebrackicry Expertise Apnlled Fcheroe Laborvtarirr window are explained in the following subsections When the Save amp Close or Save amp Continue button is clicked information entered in any of the tabbed dialog windows becomes part of the default environment file 3 2 1 General Tab The General Tab selects and sets general information x abou t the me tho d an d tools by which the EHI environment General Calibration Target Points Scene Planes Stationary Scene Camera will be set up Its parameters must be established first and ee a ee it they are changed midway through a configuration the Head Tracker Sensor to Eye Vector Coordinates in Sensor Coordinate Frame Either enter the x y z values OR use the Calculate procedure entire EHI setup may need to be redone 3 2 1 1 Number of Scene Planes This value defines the number of scene planes surfaces that the operator will be defining The value entered here does not include the Calibration Scene Plane Therefore if there were only the Calibration Scene Plane then this value would equal zero Save and Close Save and Continue Restore Defaults Cancel 3 2 1 2 Head Tracker Sensor to Eye Vector Coordinates in Sensor Coordinate Frame These values define the distance of the HT Receiver to the subject s
23. T gaze intersection location on the defined scene planes Hpos 13 5 Vpos 7 36 sol OFF 3 4 1 Scene The Scene value is the Scene Plane number that the system is calculating as the intercept surface of the line of gaze It will be an integer value from zero to twenty specifying the Scene Plane first intersected by the eye line of gaze vector If no intersections are found Scene Plane O will be designated by default and the intersection coordinates will correspond to an infinite extension of Plane 0 The Scene number also specifies the Scene Plane currently being presented in the POG Display grid pattern The Scene number and graphics window will change as the subject s Point of Gaze moves between the defined scene planes 3 4 2 Magn Magn Magnification 1s the distance of the eye from the Point of Gaze displayed in the specified units inches or centimeters 3 4 3 Vpos and Hpos These values are the vertical and horizontal point of gaze coordinates They represent the y and z axis values of point of gaze on the current designated Scene Plane The values are given in the systems current units inches or centimeters 3 5 Checking environment specifications Because it is fairly easy to make a data entry error and because the EyeHead environment is completely specified by the data and procedures in the EyeHead Setup Menu See Section 3 2 EyeHead Setup it is important to check the veracity of the environment specifications
24. a mistake or not held the unio n A A pointer steady you may repeat the procedure When all DK Set Cancel 10 EYEHEAD INTEGRATION MANUAL zu ASL Eyalracking Expertise Apnlled Fcheroe Laborartarirr three points have been defined press OK to exit this dialog The digital values in the Point ABC coordinates in transmitter frame box should now correctly display the vectors that connect the transmitter with each point The procedure applies only to the scene plane specified at the top of the Scene Plane Tab Remember to do this procedure for all scene planes 3 2 3 9 Rectangular Scene Plane Boundary These values set the edges of a Scene Plane surface in terms of the Scene Plane s coordinate system This controls the location at which gaze is determined to fall off a surface Any calculated values beyond these edges will be calculated to intersect with farther surfaces along the gaze vector or on the universal Scene Plane 0 3 2 3 10 Manual Offset This field will introduce an offset of the entire coordinate frame for the current Scene Plane by the specified amount This is to attempt to correct for a systematic misplacement of the defined Scene Plane usually due to measurement errors without having to redo the entire measurement of that plane This option should be used cautiously only when there is an across the board systematic offset of an entire plane s coordinate frame 3 2 3 11 Real Time Graphics Grid Scale he
25. al gt 0 error condition Z euh e Pupil diameter most significant byte 0 loss Pupil diameter least significant byte EyeHead Scene Plane number Point of gaze horizontal y coordinate most significant byte scene monitor coordinates Point of gaze horizontal y coordinate least significant byte Point of gaze vertical z coordinate most significant byte oT RR Point of gaze vertical z coordinate least significant byte Note that 1f using the streaming mode the list in table 7 1 shows the data after decoding Each coded data field read by the host will consist of 10 bytes Bytes 4 8 carry the same information displayed on the real time grid pattern display Point of gaze coordinates are given with respect to the scene plane coordinate frame the coordinate system on that surface as defined in Section 3 2 designated by byte 4 The coordinate values are integers representing hundredths of inches or centimeters In other words 10 2 inches or centimeters would be represented by the integer 1020 29 EYEHEAD INTEGRATION MANUAL 7 3 Serial Port Configuration Eye tracker data can be output through an RS 232 port labeled Serial Out on the Eye Tracker Control Unit This port can be connected to a PC serial port The Eye Trac 6000 Control Unit Serial Out connector is a 9 pin male D type Only Transmit Receive and Ground lines are used The port is set to 8 data bits 1 stop bit no parit
26. al the operator must enter the distance from the center of the Transmitter origin to the tip of the laser pointer This value is added to the measured values in HT Pointer Tip to Point Magnitude below to calculate the HT Transmitter to Point distance 3 2 3 5 Sensor Wand Tip Position in Sensor Coordinate Frame Availability Point with sensor wand selected These values define the location of the sensor wand tip with respect to the center of the HT Sensor For the standard Sensor Wand X and Z equal 0 while Y is 4 10 inches per section 3 2 3 6 Distance from Laser to Points A B C Availability Point with Laser Gimbal method selected If the Point with Laser Gimbal method of defining surfaces 1s being used the operator must enter the distance from the end of the laser to each of the three defining points The distance values are usually measured with a ruler or tape measure EYEHEAD INTEGRATION MANUAL prac asc Eyabacking Expentien Applied Xcience Laborxrtarirr For optimal results the laser should be pointed at the dot being measured at the time of measurement The values typed into this section are the distance from each point A B and C to the end of the laser This value is added to the HT Transmitter Center to End of Gimbal Pointer Magnitude value in order to calculate the distance of each point to the center of the Transmitter This information is necessary for defining the physical loc
27. an Ascension Flock of Birds or a Polhemus 3 Space Tracker ISOTRAK or FASTRAK type system Consult ASL for comparative details Other Head Tracker types including the Ascension LaserBird and the NDI Optotrack may be available for use with EyeHead Integration Note that the Optical Tracker FR1 available for the Video Head Tracker for the R6 Pan Tilt system cannot be used for EyeHead Integration Transmitter and Sensor The transmitter source and sensor modules attach to the clearly labeled connectors on the HT electronics unit See the manual packaged with the HT system for details MHT Interface cable Connect one end of the provided HT interface cable red yellow color code to the RS232 port on the HT control unit Connect the other end of the HT interface cable to the Eye Tracker Control Unit connector labeled Head Tracker DIP switch settings Set the DIP switches on the HT electronics unit for 19200 Baud RS232 communications consult manufacturer s manual packaged with the HT system for proper DIP switch settings These settings will be factory preset for systems purchased through ASL Power On Off The Ascension Flock has no power switch The AC plug must be disconnected to power down The fly standby switch must be in the fly position during use but this is not a power switch Polhemus devices may or may not have a power switch in the electronics unit depending on the model and date of manufacture When power
28. ation of the surface in space 3 2 3 7 Point ABC Coordinates in Scene Coordinate Frame These values define the locations of the three surface defining points in the Scene Plane s coordinate system In some cases particularly if the Scene Plane being defined is the calibration scene plane Plane 0 it may be simpler to use the calibration points In this case the operator can copy the values from the Calibration Target Points values See Section 3 2 2 by pressing the Set from Calibration Points 9 7 1 23 less button Remember also that the three points must form an L shape 0 0 with point A at the bottom nght point B at the vertex and 4 point C at the upper left 3 2 3 8 Point ABC Coordinates in Transmitter Coordinate Frame These values define the locations of the three surface defining points in the HT Transmitter s coordinate system These values are set by way of tool selected in the Options for Specifying Points A B C selection on the General Tab See Section 3 2 3 3 If you have one of the three non manual entry methods selected press the Set With button to display the Set Scene Points window Using the method defined point or place the tool at each 2 appropriate point in turn and press the SET button when EIAS the pointer is held steady When the system is ready for up ie the next point the next Letter will be highlighted If you UM ee AO ae 3989 do 59m believe that you may have made
29. automatically advance to the next point Repeat the procedure for all 5 SSC points on the current Scene Plane Points can be entered out of sequence by using the up down arrows next to the Target Point Selection To check the accuracy of the positions of the five SSC points entered for the indicated plane switch to Check Mode and use the Scene Plane field and Target Point Selection field to scroll through all of the points Note the computations cannot be done correctly unless the coordinates for the current scene plane have been correctly entered as described in Section 6 2 2 Enter Scene Plane Locations of SSC Points These coordinates must be entered before doing the procedure described in this section If the SSC points for the current plane do not include 5 different horizontal and 5 different vertical coordinate values as described in Section 6 2 1 Attaching Scene Planes to the Video a pop up error message may appear saying non unique solution If this occurs click OK to erase the message box and check SSC point coordinates 6 2 4 Check SSC Environment Specification As with the other EyeHead parameters it is easy to make a mistake in entering stationary scene camera parameters Therefore the SSC setup should also be checked with the Pointer Test mode In 26 EYEHEAD INTEGRATION MANUAL prs Csi Eyabacking Expentien Apnlled Fcheroe Labar rbarkep order to the check the stationary scene camera setup the Eye Head env
30. borsehorker Configure Basic Configuration EyeHead nf Setup Pointer Test Mode Activate EyeHead Integration Data Display Initialize Enable Stationary Scene Camera Stationary Scene Camera Target Points Copy EveHead Configuration Read EveHead Configuration Save EveHead Configuration Import From old enw File Note Set Target Points mode is not used in EyeHead Integration Changing the Target Points from the Calibration Set Target Points will have no valid effect EYEHEAD INTEGRATION MANUAL 5p ASL Eyebrackicny Expertise Apnlled Fcheroe Labar rbarkep 3 EyeHead Environment Specification The EyeHead environment consists of the magnetic head tracker transmitter and up to 20 surfaces of interest These surfaces are assumed to be flat although curved surfaces may be approximated as one or more flat surfaces and are assumed to be fixed not moving with respect to the magnetic transmitter Typical surfaces include monitor screens keyboards poster displays slide screens walls etc It is recommended that the environment be arranged so that all surfaces are within the pointing range of the HT Laser Gimbal Pointer mechanism or the HT Pointer Wand depending on which method is being used to define the surfaces See Section 3 2 3 3 Options for Specifying Points A B C If it is not possible for all surfaces to be within range of the pointing device there are other more difficult ways to specify
31. can also be confirmed by checking the numerical display values If the EyeHead display does not correctly match the pointer position check values entered in the various Setup windows check the distances measurements from the transmitter to points A B and C on the scene planes and try re doing the Point Definition pointing procedure for points ABC TIP Common errors often include negative signs incorrectly placed when specifying coordinates If a visible offset error 1s observed on any scene plane and cannot be corrected by the steps suggested in the previous paragraph then enter appropriate compensating offsets for that scene plane number in the Individual Scene Plane window See Section 3 2 3 10 Manual Offset The offsets are expressed in the coordinate frame defined for that scene plane This only works for errors that are similar everywhere on the scene plane For example if the cursor is always inch to the right of the proper position 14 EYEHEAD INTEGRATION MANUAL i ASL Evelrackieny Expvertise Apnlled Feber Laborxrtarir 4 Exit from the Gimbal Test mode by again edd EHI selecting Pointer Test from the EyeHead menu POINT w Pointer Test Mode TEST or clicking on the shortcut icon 3 6 Stationary Scene Camera optional If the user wants to receive a video feed of the stimuli or environment with a superimposed Point of Gaze cursor a Stationary Scene Camera SSC must be configured Any video feed
32. cedure used during Regular system operation mode non EHI Before proceeding be sure that the Stationary Scene Camera is properly connected and aimed as described in Section 6 1 Scene Camera Installation 25 EYEHEAD INTEGRATION MANUAL From the EyeHead menu select Stationary Scene Camera Target Points This will open the Set SSC Target Points window Evelrackiag Expectise Apnlled science Laborartarirer EyeHead Stationary Scene Camera Target Points While this window is active and in Set Mode moving the UE EXE Note When this form is opened mouse position within mouse cursor over the POG Display window will control the FU Deut cert RD ocean rene POG cursor on the Scene Out video feed To enter target point use mouse to position POG indicator on Video Scene Display and left click Made J While in Set Mode pressing the left mouse button while in the Set C Check POG Display will cause the currently selected SSC Target Scene Plane f0 x Newt gt Point on the currently selected Scene Plane to be set to that ICT Um ee location on the Scene Out video location Scene Plane Coordinates Y 0 Z 0 Cancel For each of the 5 Points on each Scene Plane depicted in the SSC move the cursor over the location of the point in the video image Press the left mouse button when in the correct location This will define the video coordinates for the current point The Target Point Selection field will
33. cycling any device using the power cord be sure to use the AC wall socket not the DC connector that connects the external power supply to the electronics unit Self Test Most units have a self test mode when first powered up and provide feedback to indicate successful or unsuccessful self test Read the manufacturer s manual to determine the feedback code For example the Ascension Flock has a front panel light that blinks several times and then remains solidly on if the self test finds no errors The light will continue to blink if the self test fails If the HT unit self test fails power down the unit check all connections then try again Consult ASL if still unsuccessful MHT Data Display The HT data display consists of 3 position and 3 orientation values The position values are the position of the magnetic sensor with respect to the transmitter x y and z axes The orientation values are the azimuth az elevation el and roll rl angles often called Euler angles that describe the orientation of the sensor axes with respect to the transmitter 32 EYEHEAD IMTEGRATION MANUAL a ASL Eyebrackicey Expiertizz Apnlled Fcheroe Labarrbarkeg axes Position values are expressed in inches or centimeters if Use Metric System is enabled and orientation values are expressed in degrees If the HT system is communicating properly with the eye tracker computer the HT display values should change when the sensor moves a
34. d pupil diameter If the MHT system is enabled the file also includes the position and orientation or the magnetic sensor with respect to the head Note that this information does not directly indicate what surfaces or objects in the environment are being viewed More useful to the operator the ehd file will record the Integrated Scene Plane EyeHead data which consists of the identification number of the Scene Surface being viewed coordinates of the gaze point on that surface the distance of the eye from the spot being fixated and the pupil diameter File 5 1 Opening a New Data File iil New Data File From the File pull down menu the New Data File item will open a New File dialog to create and open a new data file for ASSMAN aaie Msc vow Heb o recording eye tracker data When EyeHead Integration is TRES HT an R POG Display Eye Tracker Data _ Online active this file will automatically be an ehd file Pupil Diam i h 57 56 v 55 Scene POG h 29 7 y 181 8 After naming the file and pressing Save you will be asked to enter a File Description This description will be saved in a header with the data file and will be visible with EyeNal ADAT 0 EYEHEAD Scene 0 Magn 108 When a data file is open the file path and name will be listed in the File Info section of the Main window Additionally the pde activation state of the toolbar will alter to disallo
35. dicate that the system is in a paused state It will also indicate the segment number of the previously recorded segment You must stop recording in order to close a data file or exit the software 5 3 Close Data File When you are finished recording data after an experimental File session you must close the data file This finishes crucial file TE PE ll terminator writing and removes the interface software s write access to the file The data file will not be available to access by other software until it has been closed 21 EYEHEAD INTEGRATION MANUAL lt lt ASL Eyebrackicny Expertise Apnlled science Laborxrtarire 6 Stationary Scene Camera Optional If the system 1s equipped with a Stationary Scene Camera SSC or equivalent video source then integrated EyeHead data can be displayed as a Point of Gaze cursor superimposed on the video image from this fixed video source The Head Mounted Scene Camera that 1s a standard component of the Model H6 Head Mounted eye tracking system can be removed from the headband or helmet and with the proper cable used as the stationary camera If some other camera is used it may either be color or black and white but must output composite video In the North America this will be NTSC format In other locations it may be PAL format Consult ASL if unsure Any type of lens may be used on the stationary scene camera in order to best capture the field of interest but if a very wide
36. e protocol for SERIAL OUT is described in Section 7 Serial Output Interface Installation of a magnetic head tracking system is discussed in Section 8 of this manual Installation and placement of the transmitter mount and gimbal pointer assembly 1s described in section 9 Many of the procedures described below assume that the magnetic transmitter mount and gimbal pointer assemblies have been properly installed and that the MHT unit is properly connected A training video for EyeHead Integration setup is available for download form the Tech Support Website http techsupport a s l com or on a CD that accompanied some systems EYEHEAD INTEGRATION MANUAL 2 Interface Software Software for EyeHead Integration is contained was part of the User Interface software supplied with the eye tracker when the EyeHead Integration option is included The User Interface software must have both Head Mounted Optics type selected and a Head Tracker type active from the Basic Configuration window for EyeHead Integration to be available The EyeHead pull down menu has the following selections The items in the Setup Menu contain the EyeHead configuration dialogs that provide the system with information about the physical environment and various user selectable options The remaining items enable various EyeHead program functions The menu choices are all explained in the subsequent sections ASL Eyatracking Expertise Applied Fcheroe La
37. e gimbal assembly The gimbal assembly is fastened to the top and bottom plate of the transmitter mount with two black Delrin pivots The pivots fit in the countersunk holes on the top and bottom pieces of the transmitter mount assembly To attach the gimbal assembly 1 Remove the white round head 1 4 20 screw to remove the top pivot 2 Hold the gimbal in place so that the bottom pivot fits in the indent on the bottom plate 3 Slide the top pivot into place so that it fits in the indent on the top plate and replace the 1 4 20 screw to fasten it 4 Adjust the tension by turning the bottom pivot so that it is finger tight 9 3 Laser Pointer Assembly Locate the wand with the laser pointer at one end If the wand contains the pen laser type of pointer the laser assembly has a small button that must be held down to activate the laser CAUTION This is a class II laser Do not look directly at the laser source or its mirror reflection Look only at its reflection on diffuse surfaces If the laser assembly is not yet fastened to the wand notice that there is a holder or cup for the sensor in the wand Notice also that the wand has a short section on one side of the cup extension A and a longer section on the other side extension B The laser will fasten to the long end of the wand in other words the end farthest from the cup wand extension A laser holder sensor cup wand extension B ry 16 5 Note wand ext
38. e y axis extends to the right The unit will correctly measure the position and orientation of the sensor with respect to the transmitter when the sensor is between 4 and 24 inches from the transmitter and in the hemisphere defined by positive x values in the transmitter coordinate system Large metallic objects or devices that produce electromagnetic emissions near the transmitter or sensor may produce errors or noisy data The system is usually shipped from ASL with the transmitter already installed in an acrylic mounting assembly consisting of a back plate that can be fastened to a mounting surface a top plate two side 36 EYEHEAD IMTEGRATION MANUAL a ASL Eyebrackicey Expertise Apnlled Fcheroe Laborxrtarirer plates and a small bottom plate Four screws are also provided to fasten the assembly to a mounting surface The assembly must be mounted to a stable non metallic surface It is suggested that the assembly be mounted so that the transmitter will be behind and slightly above the subject s head When the subject is wearing the helmet with magnetic sensor attached and is in the nominal center position the sensor should be about 5 10 inches from the transmitter It is suggested that the transmitter be roughly straight and level with the x axis pointing towards the subject and the z axis pointing down Note that this implies a vertical mounting surface To attach the assembly to a mounting surface 1 Remove the mounting
39. ear as straight as possible in the stationary scene camera image 22 EYEHEAD INTEGRATION MANUAL P ASL Eyebrackicny Exp ertinz Applied Fcheroe Laborxrtarirer The external SSC is connected to the ASL Control Unit by way of the Remote Scene port Within the Interface Software the Video Source setting found in the Advanced Configuration window should be set to Remote Scene Connector Configure Advanced Configuration Once properly positioned ensure that the camera is well secured and is not likely to be moved or redirected accidentally If the camera supplied as the head mounted scene camera will be used as the stationary camera consult ASL for instructions for removing the camera and mounting 6 1 2 Scan Converter Connect the stimulus computer or other image producing system to the Scan Converter the stimulus display monitor and the ASL Control Unit as shown The Scan Converter is connected to the ASL Control Unit by way of the Remote Scene port Within the Interface Software the Video Source setting found in the Advanced Configuration window should be set to Remote Scene Connector 6 2 Stationary Scene Camera Software Configuration The video signal input through the Remote Scene port on the ASL Control Unit See Section 6 1 Scene Camera Installation can be output over the Scene Out port with a cursor indicating the Point of Gaze superimposed on the image While using EyeHead Integration the system
40. en are very close to zero It will not be possible to make the values exactly zero The position as opposed to the orientation of the headgear does not matter so long as the sensor and the eye location are within 36 inches of the transmitter center With Az El and RI values nearly zero record the MHT x y and z values displayed on the e5Win screen Let us call these the position values Being careful not to move the headgear remove the sensor from its mounting plate and hold it at the eye position on the Styrofoam head or the marked eye position if some other marking method was used With the sensor held at approximately the eye position again record the MHT x y and z values displayed on the e5Win screen Let us call these the position 2 values Subtract the position 1 values from the position 2 values to compute the x y and z values of the sensor to eye vector A very rough application of the ruler estimation method described above can be used as a check to see that the values are sensible 43
41. ension B can be removed to shorten wand Wand and laser assembly shown mounted to Ascension Flock type transmitter mount Note Wand extension B is not standard and is supplied only upon request 38 EYEHEAD IMTEGRATION MANUAL a ASL Eyebrackicey Cupirtigh Apnlled cemoe Laboravtarirr The wand fastens to the gimbal with a fastener that has a threaded stud on one end and a larger smooth stud on the other The threaded end screws into the gimbal elevation arm and the other end slides into a socket at the end of wand extension A Two setscrews in wand extension A fasten the wand to the stud First screw the threaded end of the stud onto the gimbal arm Then slide the wand socket over the smooth end of the stud being sure to push the wand firmly against the gimbal arm Tighten the setscrews with a hex wrench Be sure to tighten the setscrews quite firmly The magnetic sensor must be mounted in the cup for part of the environment specification procedure If a shorter wand is more convenient simply remove the longer wand extension extension B and fasten the laser holder directly to the sensor cup This might be appropriate if the physical environment is very cramped or if one of the scene plane surfaces is very close to the transmitter Whatever the configuration used be sure the correct length distance from end of the laser holder to the center of the magnetic transmitter is correctly entered in the Individual scene plane parameters dialo
42. etic sensor attached and 1s 1n the nominal center most normal position the sensor should be about 5 10 inches from the transmitter It is suggested that the transmitter be roughly straight and level with the x axis pointing towards the subject and the z axis pointing down 9 1 Transmitter Mount amp Gimbal for Ascension Flock of Birds The Ascension transmitter is roughly a cube approximately 3 25 inches square with flanges and mounting holes at its base and a cord extending from the rear of the base The origin of the 34 EYEHEAD IMTEGRATION MANUAL a ASL Eyebrackicey Expiertizz Apnlled Fcheroe Laborvrtarirr transmitter coordinate system 1s the center of the set of coils imbedded in the block The nominal straight and level orientation is mounting side flanges and mounting holes facing down In this orientation the positive x axis extends out of the face opposite to the cord the positive z axis extends down and if facing in the positive x direction the positive y axis extends to the right The unit will correctly measure the position and orientation of the sensor with respect to the transmitter when the sensor is within 36 inches of the transmitter and in the hemisphere defined by positive x values in the transmitter coordinate system Large metallic objects or devices that produce electromagnetic emissions near the transmitter or sensor may produce errors or noisy data neck olote pees Peia Per Paare kay
43. g towards the subject and the z axis pointing down 35 EYEHEAD IMTEGRATION MANUAL a ASL Eyebrackicey Expiertizz Apnlled Fcherce Laborehorker The rectangular gimbal assembly is fastened to the top and bottom plate of the transmitter mount with two pivots 1 Thread the top pivot into the top of the inner gimbal if not already attached If the bottom pivot is attached to the gimbal remove the bottom pivot by removing the plastic screw 2 Rest the top pivot in the indent on the shee Heim top mounting plate just above the ir mh ale pti center of the transmitter 3 Insert the bottom pivot between the inner gimbal and the bottom plate so that its point fits in the indent on the u bottom plate and fasten it with the amba enm plastic screw provided bollom graui 9 2 Transmitter Mount amp Gimbal for Polhemus 3 Space or Isotrak The Polhemus transmitter or source is a black or tan block 2 4 inches long 1 4 inches high and 1 4 inches wide It has flanges and mounting holes at its base and a cord extending from the rear of the base The origin of the transmitter coordinate system is the center of the set of coils imbedded in the block The nominal straight and level orientation is mounting side flanges and mounting holes facing up In this orientation the positive x axis extends out of the face opposite to the cord the positive z axis extends down and if facing in the positive x direction the positiv
44. g window as described in Section 3 2 3 Scene Planes Tab For the standard wand mounted on the Ascension Flock type gimbal this measurement will be about 36 inches when using the full wand 31 inches for the wand plus 5 inches from the outer edge of the azimuth gimbal to the azimuth hinge The value will be about 19 5 inches if the wand extension B is removed For the Polhemus 3 Space Tracker type gimbal these measurements will be 35 and 18 5 inches respectively These values can vary slightly from sample to sample and users are advised to check the measurements with a ruler When not using the pointer for Gimbal Setup as described in Section 3 of this manual the pointer can be removed from the gimbal assembly if desired To remove the pointer wand loosen the setscrews at the gimbal end of the wand and slide the wand off the stud The entire gimbal assembly may also be removed from the source mount if desired 9 4 Laser Pointer CAUTION The pen laser is a class II laser Do not look directly at the laser source or its mirror reflection The pen laser itself 1s a small plastic tube with a small removable panel for inserting batteries When used in the gimbal pointer it is important that the laser beam is well aligned with the pointer in other words it must be parallel to the imaginary line connecting the sensor and the transmitter origin To accomplish this the laser barrel 1s fastened to a black Delrin laser holder with 8 adjustable setscre
45. ironment must already have been properly specified as described in Section 3 EyeHead Environment Specification Select Enable Stationary Scene Camera from the ss EyeHead menu or click the SSC Quickbutton to Sara NE rr activate the Stationary Scene Camera mode Mun SQ CISE diea E A Enter Pointer Test Mode as discussed in Section 3 5 1 EveHead ER Pointer Test Painter Test Made POINT TEST Direct the Pointer at the surfaces that are part of the SSC environment and watch the Scene Monitor A cursor superimposed on the video image from the stationary scene camera should correctly indicate the position pointed to If the cursor does not appear to correctly follow the laser spot check to see if the cursor on the Interface program EyeHead grid pattern display correctly follows the Pointer location If the cursor on the grid pattern display correctly follows the pointer then an error was likely made in SSC environment specification Re Check the procedures from Section 6 2 2 Enter Scene Plane Locations of SSC Points and Section 6 2 3 Enter Scene Camera Locations of SSC Points If the grid pattern display does not correctly follow the pointer check the EyeHead environment specifications from Sections 3 2 EyeHead Setup 6 3 Using SSC during Real Time Eye Head Integration Select Enable Stationary Scene Camera from the EveHead EyeHead menu or click the SSC Quickbutton The aa ae T SSC can only be enabled when EHI is enabled a du
46. n e This value defines how many units default inches are represented by SEE EEE od a TE IBGE each grid line in the EHI Point of Gaze Display on the main interface IBEBEEBEEEBSI screen In RRR IEMENEBNENEBNEBNEENI IDR Eee IBEBBBEBEBSNI m 3 2 4 Stationary Scene Camera RAM cnra Pare gi Kets ES raisin Integrated EyeHead data can be displayed as a point of gaze cursor superimposed on the Scene Out image For each Scene Plane for which the operator wants this video output five points on the surface must be defined 11 EYEHEAD INTEGRATION MANUAL zu ASL Evelracking Expertise Apnlled Fcheroe Laborsehorker No two points in this pattern can have the same horizontal and vertical coordinates or the overlay will fail to properly function For each of the five points on each Scene Plane enter the Y Z coordinates in that Scene Plane s coordinate system The recommended layout of these points 1s a zigzag pattern as shown to the right Additional Stationary Scene Camera configuration must also be performed in the Stationary Scene Camera Target Points window See Section 6 2 Stationary Scene Camera Software Configuration Check the Enable box at the top nght to enable the stationary scene camera for the selected scene plane The system will not display a cursor for this scene plane unless it is enabled For a detailed explanation of how to set up an environment with a stationary scene camera
47. n the box or by typing the desired number into the box ASL B a Eyelracking Expertise Applied Fcheroe Laborartarirr x Calibration Type Standard Tell subject to I Save Current Point Scene POG Indicator look at point E lt Space gt Target Points Calculated POG Calibrate and Exit New Calibration Close Dialog To store the calibration for the current point press the Save Point button or press the spacebar on the keyboard This will take the currently computed eye feature Pupil and CR positions and the Subjects head position and use them as the values for the current point in computing the Point of Gaze calibration The newly input points are not used to compute POG until the Calibrate and Exit button is pressed 4 1 2 Understanding Calibration The raw data measured by the Eye Tracker is the separation between the pupil center and the corneal reflection CR center The relation between these raw values and eye line of gaze differs for each subject and for different optical units and scene camera positions The purpose of the eye calibration is to provide data that will allow the Eye Tracker processor to account for individual subject differences The objective 1s to have the subject look at fixate on each of the nine calibration points This procedure must be performed for every subject In EyeHead Integration this information is combined with Head Position tracking in order to compute
48. nd should match the actual position of the sensor with respect to the transmitter Actually the values will probably be constantly changing even when the sensor is stationary due to system and environmental noise Communication between the HT system and the eye tracker computer can be verified by checking the displayed HT values on the Eye Tracker Interface screen data window Remember that the position values should correspond to the distance between the center of the sensor and the center of the transmitter along each transmitter coordinate axis The orientation angles represent the orientation of the sensor coordinate frame with respect to the transmitter frame If the values seem reasonable move the sensor and check to see if values have changed in the proper direction If the values still seem reasonable the HT system is probably communicating properly with the eye tracker If values do not seem reasonable select Reset HT from the HT pull down menu and try again If still not reasonable disables HT from the pull down menu power cycle the HT electronics unit re enable HT from the pull down menu and try again 33 EYEHEAD IMTEGRATION MANUAL zu ASL Eyelracki Expiertizz Applied science Laborxrtarirer 9 Transmitter Mount amp Laser Gimbal Assembly A system with the EyeHead Integration option usually includes a plastic mounting bracket for the magnetic transmitter which is also designed to support a gimbaled laser pointi
49. ng device The user must arrange for an appropriate support surface to hold the mounting bracket The mounting assembly requires a stable nonmetallic vertical surface The easiest method is probably to use a wooden post supported by a heavy metal or wooden magnetic transmitter base plate Such a post can be made from American magnetic sensor standard 4 by 4 lumber actual cross section 1s about 3 5 inches square or something roughly equivalent The mounting surface should be at least 3 inches wide A The transmitter mounting assembly can be fastened to the wooden post with standard wood or wallboard foste ee d screws e g 1 75 inch number 8 wood screw or wallboard screw Any other method for placing a non metallic mounting surface in the proper position is also acceptable For example a wooden or plaster wall is an appropriate mounting surface so long as there is not a large metal beam in the wall near the mounting place Other acceptable materials for a mounting surface include plastics fiberboard Formica etc i a i Fm Te He enc WEI hedd bon meuntec optics The Transmitter is fairly heavy and must not move once the system is calibrated for a particular environment s geometry so the mounting arrangement should be quite sturdy Optimal placement for the transmitter with respect to the subject is also shown on the sketch in figure above When the subject is wearing the Head Mounted Optics with the magn
50. r boundary must also be determined for each scene plane including the calibration plane and is specified by a top bottom left and right coordinates The top coordinate is the z value at the top edge of the surface minimum z value on the surface the bottom coordinate 1s the z value at the bottom edge of the surface max z value Similarly left and right coordinates are the minimum and maximum y values This boundary specifies the possible eye point of gaze intersection area for that scene plane EXAMPLE if your scene plane was a 17 inch monitor your scene boundary coordinates might be Top 8 Left 8 Right 5 Bottom 8 The calibration surface is designated as plane 0 and all other surfaces as planes 1 through 20 When eye head data is integrated point of gaze values will be specified as a plane number a y horizontal value and a z vertical value The y z values will correspond to the coordinate frame that is attached to the designated plane as described above EYEHEAD INTEGRATION MANUAL ASL Three points must be chosen on each plane to enable the computer to define that plane relative to the Head Tracker HT source Looking towards the scene plane from the HT source the three points should have the relative positions shown in the drawing Note that the three points form an L shape with A at the lower right B at the vertex and C at the upper left The calibration scene may optionally have its three points defined a
51. s entered into Point 1 and Point 9 and extrapolate the other seven points symmetrically 3 2 3 Scene Planes Tab gijEyeHead Integration Setup x General Calibration Target Points Scene Planes Stationary Scene Camera The Scene Planes Tab defines all of the spatial positions of P i Net each Scene Plane in the EyeHead environment The items aac displayed in the window will contain information only for the plane specified in the Scene Plane selection field Point with gimbal laser C Manual entry type in values C Place sensor directly on points Point with sensor wand Distance from Head Tracker Origin to End of Laser fi 3 This information must be entered for all scene planes m 0 vB en including the calibration plane The calibration plane surface with subject calibration target points 1s plane number Q and all additional planes are numbered sequentially startin E Point ABC Coordinates in Scene Coordinate Frame Y Horizontal Z Vertical 3 Distance from Laser to Points 4 B C Point 40 5 PointB 137 25 Point C 44 5 1 11 Set from Calibration aot i fis ze with 1 Recall that the number of additional scene planes was fure sas vu z pz of PointC Y zu specified in the General Tab tc TEE Save and Close Save and Continue Restore Defaults Cancel 3 2 3 1 Scene Plane This field sets and displays which Scene Plane is currently being defined It
52. s follows for convenience Point A is equal to calibration target Point 9 point B is equal to calibration target point 7 and point C is equal to calibration target point 1 Other planes must simply adhere to the relative positioning described above The coordinates of the three points must be expressed in inches or centimeters 3 1 Units The user can choose to specify EyeHead environment l par ameter Ss In either English Standar d Or Metric units Restore defaults for most common configurations This choice is made in the Basic Configuration dialog HosA Votes poa R Hees Eye Stat ptics ptic System Type Monocular Binocular window Bcd Morea Oper IV Use Metric System centimeters Find the check box titled Use Metric System If Dark Pupil Optics EyeHead parameters are to be specified in metric units be sure that there is a check in this box To use Interface Pot oot s English units be sure that the box is left unchecked Eye Camera Update Rate eg If Metric units are selected all distance parameters Head Tracker Type ascension Fok gt must be specified in centimeters If English units have c zum Cancel been selected all distance parameters must be specified in inches EyeHead Setup 3 2 EyeHead Setup To begin specifying the environment for EyeHead Integration pull down the EyeHead menu Selection of the Setup sub menu will bring up the EyeHead Setup window
53. se cuadro duis When SSC is enabled the scene monitor cursor will reflect point of gaze with respect to the EyeHead Integration computed POG location 27 EYEHEAD INTEGRATION MANUAL e ASL Eyebrackicey Expirtinz Apnlled feno Laborrtarirer 7 Serial Output Interface Eye tracker data can be output through an RS232 port labeled Serial Out on the model 6000 Eye Tracker Control Unit The port is set to 57600 baud 8 data bits 1 stop bit no parity Other baud rates are also possible consult ASL for details 7 1 Interface Cable The model 6000 Eye Tracker Control Unit Serial Out connector is a 9 pin male D type Only the Transmit Receive and Ground lines are used SERIAL OUT Signal 3 serial data from host to 6000CU 2 serial data from 6000CU to host 5 Ground This cable is equivalent to a standard RS 232 cable straight through An example is shown below of wiring for a cable to connect the eye tracker Serial Out port to a standard 9 pin COM port on a PC 9 pin male 9 pin female 2 2 3 3 5 5 7 2 Protocol and data format The data output port can be set to use either a demand mode or a streaming mode In the demand mode the host computer requests a data field by transmitting a single byte of any value In response the eye tracker transmits a field of data After a data request is received from the host the eye tracker PC will begin to transmit the requested field within one update interval In the s
54. spot remains stationary as the lathe is turned 40 EYEHEAD IMTEGRATION MANUAL zu ASL Eyebrackicey Expiertizz Applied Fcherce Laborxrtarirer 10 Analysis EyeHead data files can also be processed with the EYENAL analysis software to tabulate data calculate fixations on each plane specify areas of interest on each plane match fixations and areas of interest Also to compute various associated statistics compute statistics for dwell times within areas of interest and to plot fixation scan paths See the separate EYENAL manual for details 41 EYEHEAD IMTEGRATION MANUAL pte ASL Eyebrackicey Expiertizz Apnlled science Laborxytarirr 11 Appendices 11 1 Measuring the Sensor to Eye Vector This section describes the process for determining the Sensor to Eye Vector See Section 3 2 1 2 Head Tracker Sensor to Eye Vector Coordinates in Sensor Coordinate Frame For all head units provided by ASL this value will be provided for the customer and should be listed on a label attached to the head unit The sensor to eye vector can be estimated using a ruler and knowledge of the sensor coordinate system or can be determined using the magnetic system itself 11 1 1 Measurement Estimation with a Ruler The coordinate system attached to the Ascension Flock of Birds magnetic sensor is shown in figure 1 With the sensor fastened in place on the head gear and 5 the headgear in place on a human subject measure SH along the x
55. the appropriate relationships In most calibration procedures when a subject is known to be looking at a specific point either because of instruction or by another inductive method the operator tells the system to calibrate note the current pupil CR relationship 4 2 Checking the Calibration If the calibration has been successful the system should accurately track both the surface the subject is looking at and the location on that surface where their gaze intersects It is recommended that the operator test a calibration s accuracy by first having the subject look at the calibration points on Scene Plane 0 If these are accurate all other Scene Planes should follow suit 18 EYEHEAD INTEGRATION MANUAL in ASL Eyebrackicny Expertise Apnlled Fcheroe Laborshorker This can be checked by having the subject look at points on those Planes as well For the operator it will be most revealing to use the ABC points on these planes as these points will be visible as red circles in the POG Display 19 EYEHEAD INTEGRATION MANUAL in ASL Eyebrackicny Expertise Apnlled science Laborehorker 5 Data Recording While EyeHead Integration mode is active data is recorded in the EyeHead file format with the extension ehd as opposed to the standard Eye Data file format of eyd The EyeHead ehd file will record the raw eye data that consists of the horizontal and vertical orientation of the eye with respect to the head an
56. treaming mode no data request is required Data will continually stream from the SERIAL OUT port The data is encoded however so that the first byte of a data field can be identified 28 EYEHEAD INTEGRATION MANUAL PT ASL Eyebrackicny Expertise Apnlled Fcheroe Laborsehorker Encoding of the standard 8 byte data field 1s shown below data bbbbbbbb hbbbbbbhb bbbbbbbb bhbbbbbb bbhbbbbbb bbbbbhbh bbbbbbbh bhbhbhhh E HE HE TITE TEP TEP HII HT encoded data lbbbbbbb bbbbbhb Obbbbbbb Obbbbbbb bbbbbhb Obbbbbbb bbbbbhb Obbbbbbb Dhbbbbbb 0BnDODDDh BYTEl BYTEZ BYTES BYTE4 BYTES BYTES BYTE OVERFLOW BYTES OVERFLOW Note that most significant bit of the first data field byte is always set 1 The most significant bit of all other bytes in the data field is always reset 0 For the standard data set the encoded data field is 10 bytes long rather than 8 bytes The host computer must find 10 sequential bytes starting with a byte whose most significant bit is 1 and then decode the data by reversing the encoding process shown above Sample source code for decoding streaming data can be provided by ASL upon request If eye head integration is enabled the data field will have the contents shown in table 7 1 If eye head integration is not enabled raw eye and MHT values will be output as described in section 6 of the Eye Tracker Instruction manual Table 7 1 Standard EyeHead Integration Serial Out data field description Status 0 norm
57. w creating poe new data file allow closing of the data file and activate the E Program Fies ASL Eye TrackerGDODWyDataVTesOvetimeswqehd Recor d bu t ton State Paused Segment 0 Head Mounted Optics Units Cm Elapsed 1 19 58 60 Hz 5 2 Starting and Stopping Recording To record data to the opened data file the operator must select m Start Recording or press the Start Recording Quickbutton Immediately upon selecting Start Recording the Interface eae software will begin writing data to the data file in real time 20 EYEHEAD INTEGRATION MANUAL in ASL Eyebrackicny Expertise Apnlled cemoe Laborvtarirr Alternatively the XDAT cable can be used to start and stop recording See the Interface Software Manual for details Start Recording creates a new Segment within the data file Therefore for each instance that recording is started and stopped a new Segment will be created The File Info section of the Main interface window will indicate that the system is in a recording state It will also indicate the current segment number Note It is critical that you calibrate the subject before recording data or the recorded data will be meaningless Stop Recording will pause writing data to the data file Each File instance of starting and stopping recording will create a new Stop Recording el Segment within the data file The File Info section of the Main interface window will in
58. ws Note that the pen laser barrel may appear to be cocked at large angle within the holder This is because the laser beam is not necessarily aligned with the pen laser barrel If not fastened when shipped fasten the laser holder to the long end of the pointer wand It is fastened with a stud identical to the one that fastens the wand to the outer gimbal arm The stud is threaded at 39 EYEHEAD IMTEGRATION MANUAL a ASL Eyebrackicey Expiertizz Apnlled Fcheroe Laborvtarirer one end and smooth on the other The threaded end screws into the wand and the smooth end slides into a socket on the laser holder Two setscrews on the laser holder secure the laser holder to the stud The laser holder assembly has a cutout exposing the battery panel on the pen laser To change batteries gently remove the plastic battery panel insert replacement batteries and replace the panel Try not to pull or push on the pen laser hard enough to dislodge the setscrews holding it in position within the Delrin holder assembly If the laser should become misaligned remove the laser assembly from the wand Insert the rear end of the laser holder in a lathe or other device that rotates about a true center Mark the position of the laser spot on a diffuse non mirror surface at least a foot in front of the laser e g a board at the far end of the lathe Turn the lathe slowly by hand while watching the laser spot on the surface Adjust the setscrews until the
59. y The maximum baud rate is 57600 which is set by default Beware that serial cables come in two types Modem and Null Modem The appropriate cable Modem connects pin 2 at one end to pin 2 at the other and pin 3 at one end to pin 3 at the other A Null Modem cable connects pin 2 on one end with pin 3 on the other end It ASL Eyatracking Expertise Apnlled denos Laborrtarirr Configure Serial Port Configuration Streaming Mode J Baud Rate 57600 Default Mode EyeHead Integration Mode hdtrk el 2 pan position 2 tilt position 2 hdtrk Y 2 hdtrk Z 2 hdtrk az 2 Total message size 8 bytes is intended for connecting between two PCs and will not work with the eye tracker DK Restore Defaults Note The Serial Out cable appropriate for connecting to a PC is identical to the cable that connects Eye Tracker Controller port to the Interface PC The Serial Out port is always active so long as any items are checked in the Serial Out Port Configuration window Serial Out user selections are saved in the file E6000 cfg located in the same folder with Eye Tracker program 7 3 1 Streaming Mode If Streaming Mode checkbox is checked eye tracker will send a packet of data with every execution cycle The cycle time 1s defined by the Eye Camera frequency For example an eye tracker with a 60 Hz camera will send a serial output packet 60 times a second

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