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VR Introduction (for web3d)

VR Introduction (for web3d). Jyun-Ming Chen Fall 2001. Contents. VR Definitions VR Paradigms VR Devices. ... making systems that fool human senses ... a new media for getting your hands on information ... The difference between VR and multimedia is that VR is about creation.

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VR Introduction (for web3d)

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  1. VR Introduction(for web3d) Jyun-Ming Chen Fall 2001

  2. Contents • VR Definitions • VR Paradigms • VR Devices

  3. ... making systems that fool human senses ... a new media for getting your hands on information ... The difference between VR and multimedia is that VR is about creation ... The question ... [is] whether the created world is real enough for you to suspend your disbelief for a period of time ... VR Definitions

  4. VR Definitions (cont) • a human-computer interface • computer creates a sensory-immersing environment, which interactively responds to and is controlled by the behavior of the user • 3 I’s of VR • interactive, immersive, imaginative

  5. Generally speaking, they do achieve certain levels of 3 “I”s. Yet, they don’t look the same (and cost differently) projected reality augmented reality HUD (head-up display) tele-presence desktop VR Variations of VR

  6. Immersive VR • an immersive experience in which participants: • wear tracked head-mounted displays • view stereoscopic images • listen to 3-D sounds • free to explore and interact within a 3-D world

  7. Desktop & Projective VR

  8. Augmented VR & Telepresence

  9. Web3D and VR • You can think of Web3D as an inexpensive means to realize desktop VR • Characteristics: • Platform: the WWW browser • Graphics performance: restricted by browser and/or plug-in • Cost: none • Language/software: open-source and some proprietary

  10. VR Devices

  11. reality engine generate desired output from the cues of input sensors for example input: pos/orient of head output: scene to HMD System Architecture

  12. 6DOF (x,y,z, r,p,y) contact vs. non-contact potentiometer magnetic, ultrasound, radar absolute vs. relative Position Sensors

  13. update rate measurement per sec. latency time delay between action & result accuracy difference between actual & measured resolution minimal detectable change modes of operation streaming: sensor send data continuously one-shot: data sent when requested working envelope data property noise, interference, limitations, ... Sensor Parameters

  14. 3 stationary orthogonal antenna, producing a low freq. field receiver: another set of ortho. antennas signals of receiver to determine pos/orient hook up receiver to moving objects Magnetic Sensors

  15. Sensor noise conditioning circuitry increase near the limit of envelope accuracy degrades near metallic objects [calibration method] Multiple receiver/transmitter large envelope moving objectS data transmission speed up Magnetic Sensors (cont)

  16. from 9 distance between speaker-microphone, compute the pos/orient c = (167.6 + 0.6T)m/s each speaker activates in cycles Ultrasound Sensors

  17. pros cheaper not subject to metallic interference cons line-of-sight constraint lower update rate (than magnetic ones) background noise (bounced off surfaces) multiple spkr/mic possible Ultrasound (cont)

  18. most intuitive way to interface with virtual world gesture: human hands has a much richer vocabulary (than the 6 DOF) original goal Zimmerman, interested in computer music, wondered whether there’s a way to make music by playing air guitar 1987: optical fiber + Lycra glove + Polhemus Isotrack Data Glove

  19. most gloves handle angle flexion only Hand DOF

  20. technology determines the price and accuracy optical fiber strain gauge conductive ink sensor mechanical devices Joint-Angle Measurement

  21. basic components optics: focus; increase fov screen: CRT or LCD enclosure: hold components; provide occlusion design concerns ergonomics (wt. comfort) image quality tracking HMD

  22. group viewing cannot afford to give everyone an HMD technology shutter glasses r/b glasses spatial multiplexing image (SMI) responsive workbench Stereo Glasses

  23. important for immersive experience Stereo sound vs. 3D sound [cp. DirectSound] 3D Sound

  24. Cues for sound localization ITD (interaural time difference) IID (interaural intensity difference) Human Hearing Model • no info of front & back • head, torso, pinna scattering

  25. HTRF (head related transfer function) some data commercially available Measuring HRTF

  26. virtual sound position should be changed according to head position Foster estimates 30-50 MIPS for each sound source even more expensive for reflected sounds convolvotron source position + corresponding HRTF [convolution] D/A, then headphone commercial cards Acoustetron, Beachtron no. of sound sources, reverberation allowed, Doppler effects, ... Using HTRF

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