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VR graphics.ssu.ac. kr 1 Ultrasonic Trackers Definition: A non-contact position measurement device that uses an ultrasonic signal produced by a stationary.

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Presentation on theme: "VR graphics.ssu.ac. kr 1 Ultrasonic Trackers Definition: A non-contact position measurement device that uses an ultrasonic signal produced by a stationary."— Presentation transcript:

1 VR graphics.ssu.ac. kr 1 Ultrasonic Trackers Definition: A non-contact position measurement device that uses an ultrasonic signal produced by a stationary transmitter to determine the real-time position/orientation of a moving receiver. Input Devices

2 VR graphics.ssu.ac. kr 2 Ultrasonic Trackers Use low-frequency ultrasound to measure position; Sound produced by a fixed triangular source (speakers); Number of sources grows with the tracker work envelope; The receiver is triangular and attached to the tracked object and has three microphones; Distance is inferred from the sound time of flight; Sensitive to air temperature and other noise sources; Requires “direct line of sight”; Slower than magnetic trackers (max 50 updates/sec). Input Devices

3 VR graphics.ssu.ac. kr 3 Ultrasonic tracker (Logitech) Input Devices

4 VR graphics.ssu.ac. kr 4 Large-volume ultrasonic tracker (Logitech) Input Devices

5 VR graphics.ssu.ac. kr 5 Optical Trackers Definition: A non-contact position measurement device that uses optical sensing to determine the real-time position/orientation of an object Input Devices

6 VR graphics.ssu.ac. kr 6 Optical trackers: a) outside-looking-in; b) inside-looking-out Input Devices

7 VR graphics.ssu.ac. kr 7 HiBall 3000 wide area tracker HiBall 3000 wide area tracker (courtesy of 3rdTech Inc.) 6 optical lenses HiBall Optical Sensor HiBall Optical Sensor interior Signal conditioning electronics electronics 6 photodiodes The sensor advantages are:  High sampling rate (2000 Hz);  High accuracy (0.5 mm, 0.03°) and high resolution (0.2 mm, 0.03°)  Impervious to metallic or ultrasonic interference;  Very large tracking area (up to 40 ft x 40 ft), small weight (8 oz).

8 VR graphics.ssu.ac. kr 8 HiBall 3000 tracker HiBall 3000 tracker on an HMD on an HMD Lateral effect photo diodes

9 VR graphics.ssu.ac. kr 9 Types of VR Applications Types of VR Applications Beacon array modules (6 strips with 8 LED/strip)

10 VR graphics.ssu.ac. kr 10 Inertial Trackers No interference from metallic objects; No interference from magnetic fields; Large-volume tracking; “Source-less” orientation tracking; Full-room tracking; A newer technology. Input Devices

11 VR graphics.ssu.ac. kr 11 But… Errors grow geometrically in time! Gyroscope errors result in large position errors; Needs independent position estimation to reduce “drift”; Input Devices

12 VR graphics.ssu.ac. kr 12 InterSense Stereo Glasses tracker (courtesy of Intersense Co.) I-Cube Accel./gyro Ultrasonic emitter

13 VR graphics.ssu.ac. kr 13 InterSense Stereo stylus tracker (courtesy of Intersense Co.) Accelerometer Ultrasonic emitter

14 VR graphics.ssu.ac. kr 14 Navigation and Gesture Input Devices Navigation interfaces allow relative position control of virtual objects; Gesture interfaces allow dexterous control of virtual objects and interaction through gesture recognition. Input Devices

15 VR graphics.ssu.ac. kr 15 Navigation Input Devices Are the Cubic Mouse and the 3-D probe; Perform relative position/velocity control of virtual objects; Allow “fly-by” application by controlling a virtual camera. Input Devices

16 VR graphics.ssu.ac. kr 16 The Cubic Mouse Input Devices VC 2.2 book CD

17 VR graphics.ssu.ac. kr 17 The Microscribe (Immersion Co.) Input Devices

18 VR graphics.ssu.ac. kr 18 Gesture Input Devices Are sensing gloves such as: - Fakespace “Pinch Glove” - 5DT Data Glove; - The DidjiGlove - Immersion “CyberGlove” Have larger work envelope than trackballs/3-D probes; Need calibration for user’s hand. Input Devices

19 VR graphics.ssu.ac. kr 19 Hand work envelope vs. interface type Input Devices

20 VR graphics.ssu.ac. kr 20 The Pinch Glove (Fakespace Co.) - no joint measures, but contact detection

21 VR graphics.ssu.ac. kr 21 The Pinch Glove (Fakespace Co.)

22 VR graphics.ssu.ac. kr 22 The glove interface: a) five-sensor version; b) 16-sensor version A) One optical fiber/finger Roll/pitch sensing Two sensors/finger plus abduction sensors 5DT Data Glove 100 datasets/sec, 12 bit A/D flexion resolution, wireless version transmits data at 30 m, needs calibration

23 VR graphics.ssu.ac. kr 23 5DT Data Glove

24 VR graphics.ssu.ac. kr 24 5DT Data Glove Input Devices

25 VR graphics.ssu.ac. kr 25 Inexpensive wired glove for computer animation; Uses capacitive sensors (two per finger) and a 10-bit A/D converter (1,024 points); Can do 70 hand configuration reads/sec.; Communicates with the host over an RS232 (19.2 k) The Didgiglove

26 VR graphics.ssu.ac. kr 26 The CyberGlove Uses linear sensors – electrical strain gauges; Angles are obtained by measuring voltages on a Wheastone bridge; 112 gestures/sec “filtered”. Sensor resolution 0.5 degrees, but errors accumulate to the fingertip (open kinematic chain); Needs calibration when put on the hand; Is expensive (about $10,000)

27 VR graphics.ssu.ac. kr 27 The CyberGlove (Vertex Co.) VC 2.3 on book CD

28 VR graphics.ssu.ac. kr 28 SpecificationsPinch Glove5DT Data GloveDidjigloveCyberGlove Number of sensors Sensor type Record/sec Sensor resolution Communication rate Wrist sensors 7/glove (2 gloves) Electrical NA 1bit (2 Points) Wired (19.2kb) None 5 or 14/glove (1 glove) Fiber-optic 100(5DT 5W), 200(5DT 5) 8bit (256 Points) Wireless(9.600kb) Wired(19.2kb) Pitch (5DT 5 model) 10/glove (2 gloves) Capacitive bit (1024 points) Wired (19.2kb) None 18 or 22/glove (1 glove) Strain gauge 150(unfiltered) 112(filtered) 0.5° Wired (115kb) Pitch and yaw


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