1. Tracking Gökhan Tekkaya Gürkan Vural Can Eroğul

2. Outline Tracking –Overview –Head Tracking –Eye Tracking –Finger/Hand Tracking Demos

3. Tracking - Purpose To update the visual display based on the viewers head position and orientation. Instead of tracking the viewer's eyes directly, we track the position and orientation of the user's head. From this we determine the position and orientation of the two eyes.

4. Tracking - Overview We may also be tracking the user's hand(s), fingers, legs or other interface devices. Want tracking to be as 'invisible' as possible to the user. Want the user to be able to move freely with few encumberances

5. Tracking - Overview Want to be able to have multiple 'guests' nearby Want to track as many objects as necessary Want to have minimal delay between movement of an object and the detection of the objects new position / orientation (< 50 msec total) Want tracking to be accurate (1mm and 1 degree)

6. Tracking Devices - Electromagnetic large transmitter and one or more small sensors. transmitter emits an electromagnetic field. sensors report the strength of that field at their location to a computer sensors can be polled specifically by the computer or transmit continuously.

7. Tracking Devices - Electromagnetic uses: –projection based systems, HMDs advantages are: –large tracking volume (approx 10 feet / 3 meters) –no line-of-sight restriction –sensors are small and light –technology has been around for a while disadvantages are: –affected by metal in the nearby area –latency can be high (0.1 seconds) –accuracy is low in large volumes –somewhat expensive

8. Tracking Devices - Electromagnetic Polhemus: –Motion Tracking: LIBERTY LATUS LIBERTY PATRIOT FASTRAK MINUTEMAN –Scanning: FastSCAN –Eye Tracking: VisionTrak

9. Tracking Devices - Electromagnetic

10. Tracking Devices - Mechanical rigid structures with multiple joints one end is fixed, the other is the object being tracked could be tracking users head, or their hand physically measure the rotation about joints in the armature to compute position and orientation structure is counter-weighted - movements are slow and smooth Knowing the length of each joint and the rotation at each joint, location and orientation of the end point is easy to compute.

11. Tracking Devices - Mechanical

12. uses: –BOOMs, Phantom advantages are: –low latency –high accuracy –sensors are small and light –technology has been around for a while disadvantages are: –small volume –only track one object at a time

13. Tracking Devices - Acoustic small transmitter and one medium sized sensor each transmitter emits ultrasonic pulses which are received by microphones on the sensor (usually arranged in a triangle) as the pulses will reach the different microphones at slightly different times, the position and orientation of the transmitter can be determined

14. Tracking Devices - Acoustic Logitech: –6 degrees of freedom –3D and 2D modes –Ultrasonic Technology –High level of ruggedness –PC and Unix compatibility –250 dpi resolution/ 3D mode –400 dpi resolution/ 2D mode

15. Tracking Devices - Acoustic

16. Tracking Devices - Optical LEDs or reflective materials are placed on the object to be tracked video cameras at fixed locations capture the scene image processing techniques are used to locate the object With fast enough processing you can also use computer vision techniques to isolate a head in the image and then use the head to find the position of the eyes

17. Tracking Devices - Optical A. R. T. system from Germany:

18. Tracking Devices - Inertial self-contained gyroscopes / accelerometers used knowing where the object was and its change in position / orientation the device and 'know' where it now is tend to work for limited periods of time then drift.

19. Tracking Devices - Combinations self-contained gyroscopes / accelerometers used knowing where the object was and its change in position / orientation the device and 'know' where it now is tend to work for limited periods of time then drift.

20. Tracking Devices - Combinations Intersense uses a combination on Acoustic and Inertial. Inertial can deal with fast movements and acoustic keeps the inertial from drifting