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What is Virtual Reality?

What is Virtual Reality? “A high-end user interface that involves real-time simulation and interaction through multiple sensorial channels.” (vision, sound, touch, smell, taste). Type of VR systems. Immersive Computer generated images will replace the real world view

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What is Virtual Reality?

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  1. What is Virtual Reality? “A high-end user interface that involves real-time simulation and interaction through multiple sensorial channels.” (vision, sound, touch, smell, taste)

  2. Type of VR systems • Immersive • Computer generated images will replace the real world view • The generated images will react to the position and orientation of the user’s head • Non-Immersive • Users are able to view the virtual world however, they are still aware of the real world • i.e. viewing the VE through a monitor • Hybrid • Permits the user to view the real world with virtual images superimposed over this view • Also known as augmented reality

  3. VR is an integrated trio of “Immersion”, “Interaction” and “Imagination”

  4. Let watch some images / clips http://www.joelfletcher.com/3d-nature.html http://www.youtube.com/watch?v=ZKw_Mp5YkaE http://www.youtube.com/watch?v=he5mZX1sRXk&feature=related http://www.physorg.com/news/2011-04-virtual-reality-scent-human.html

  5. Input Devices:Trackers, Navigation and Gesture Interfaces

  6. Input Devices • Virtual objects have 6 degrees • of freedom (D.O.Fs): • three translations; • three rotations. 3-D System of coordinates of a VR object

  7. Input Devices Trackers measure the motion of “objects” such as user’s wrist or his head vs. a fixed system of coordinates. Technologies to perform this task: Mechanical trackers (special cases); Magnetic trackers (prevalent); Ultrasonic trackers (less used); Inertial/ultrasonic trackers (new). Vision-based trackers (new)

  8. Input Devices

  9. Input Devices Tracker characteristics: Measurement accuracy Measurement rate – Readings/sec; Sensing latency; Sensor noise and drift; Measurement repeatability; Tethered or wireless; Work envelope; Sensing degradation .

  10. Accuracy Resolution Real object position Tracker position measurements Input Devices Tracker characteristics:

  11. Tracker data Real object fixed position Signal noise Time Input Devices Tracker characteristics:

  12. Tracker data Sensor drift Time Input Devices Tracker characteristics: Real object fixed position

  13. Tracker data Real object position Sensor latency Time Input Devices Tracker characteristics:

  14. Input Devices Mechanical Trackers Definition: A mechanical tracker consists of a serial or parallel kinematic structure composed of links interconnected by sensorized joints.

  15. Input Devices • Mechanical Trackers • Pros • Use sensors imbedded in exoskeletons to measure position; • Have extremely low latencies; • Are immune to interference from magnetic fields and large metal objects; • Cons • But limit the user’s freedom of motion; • Can be heavy is worn on the body

  16. Input Devices Exoskeleton structure Interface With computer

  17. Input Devices Magnetic Trackers Definition: A magnetic tracker is a non-contact position measurement device that uses a magnetic field produced by a stationary TRANSMITTERto determine the real-time position of a moving RECEIVER element

  18. Input Devices • Magnetic Trackers • Use low-frequency magnetic fields to measure position; • The receiver is attached to the tracked object and has three perpendicular antennas; • Distance is inferred from the voltages induced in the antennas .. Need calibration

  19. Metal in lab double ceiling Polhemus Long Ranger tracking errors (Rutgers)

  20. Input Devices 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.

  21. Input Devices • Ultrasonic Trackers • Use low-frequency ultrasound to measure position; • Sound produced by a fixed triangular source (speakers); • 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).

  22. Input Devices Ultrasonic tracker (Logitech)

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

  24. Input Devices Optical trackers: a) outside-looking-in; b) inside-looking-out

  25. Outside-looking in: Vicon MX • Uses 4 Mpixel cameras with own 120 LED array (infrared, or visible red). Accuracy 0.02 of a pixel, • Camera has real-time onboard image processing (masking and thresholding) • Resolution 2352x1728 @ 160 fps • 8 cameras are connected to a MX net unit which then communicates with the PC

  26. Input Devices • Outside-looking in: Vicon MX • MX Link connects several MX Net units for more cameras • To interface with other devices like a force plate, sensing glove or eye tracker – use a MX control unit. • User wears reflective markers (small spheres).

  27. Input Devices Inside-out optical tracker advantages • The best accuracy is close to the work envelope. • Very large tracking surface and resistance to visual occlusions (line of sight).

  28. Input Devices • Hybrid Ultrasonic/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.

  29. I-Cube Accel./gyro Ultrasonic emitter InterSense Stereo Glasses tracker (courtesy of Intersense Co.)

  30. Accelerometer Ultrasonic emitter InterSense Stereo stylus tracker (courtesy of Intersense Co.)

  31. Input Devices • Navigation and Gesture Input Devices • Navigation interfaces allow relative position control of virtual objects (including a virtual camera); • Gesture interfaces allow dextrous control of virtual objects and interaction through gesture recognition.

  32. Input Devices • Navigation Input Devices • Are the Cubic Mouse, the trackball and the 3-D probe; • Perform relative position/velocity control of virtual objects; • Allow “fly-by” application by controlling a virtual camera.

  33. Input Devices VC 2.2 book CD The Cubic Mouse

  34. Input Devices Trackballs

  35. Input Devices The Microscribe (Immersion Co.)

  36. Input Devices • Gesture Input Devices • Are sensing gloves such as: • - Fakespace “Pinch Glove” • - 5DT Data Glove; • - The DidjiGlove • - Immersion “CyberGlove” • Need calibration for user’s hand.

  37. Input Devices Finger Degrees of Freedom

  38. Input Devices Hand work envelope vs. interface type

  39. The Pinch Glove (Fakespace Co.) - no joint measures, but contact detection

  40. 5DT Data Glove One optical fiber/finger A) 5DT Data Glove Ultra Roll/pitch sensing 100 datasets/sec, 12 bit A/D flexion resolution, wireless version transmits data at 30 m, needs calibration The glove interface: a) five-sensor version; b) newer design

  41. 5DT Data Glove - continued Two sensors/finger plus abduction sensors Two gloves use one Bluetooth 2.4 GHz transmitter on the user’s belt The glove interface: a) 14-sensor version; b) wireless kit

  42. Input Devices 5DT Data Glove

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