IVR Chapter 4 Representation of Visual World
Questions about the lecture 'Introduction to Virtual Reality' of the RWTH Aachen Chapter 4 Representation of Visual World
Questions about the lecture 'Introduction to Virtual Reality' of the RWTH Aachen Chapter 4 Representation of Visual World
Set of flashcards Details
| Flashcards | 95 |
|---|---|
| Language | English |
| Category | Computer Science |
| Level | University |
| Created / Updated | 03.02.2017 / 10.02.2017 |
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What are the human factors for vision?
Human factors are the eye, percepts 3D visual depth cues and photometry
What are the characteristics for traditional CG? [5]
1. Perspective shortening
2. Occlusion of objects
3. Light and shadows
4. Texture gradients
5. Atmospheric perspective
What is perspective shortening?
Away/smaller object → smaller visual angle
What is light and shadows?
Light and shadows create perception of depth
What are the characteristics for VR CG? [3]
1. Stereopsis
2. Ocular motor factors with accommodation and convergence
3. Motion parallax
What is the technology for vision?
Technology is HMD (Head) or RMD (Room) with graphical processing units
What are the algorithms for generation in vision?
Geometrical modeling
What are the algorithms for rendering in vision? [3]
1. Rendering pipeline
2. Stereoscopic projections
3. Viewer-centered projections
What are the algorithms for global effects in vision? [2]
1. Ray-Tracing
2. Radiosity
What are the human factors for audio?
Human factors are the ear, percepts 3D audio depth cues and psychoacoustic
What is the technology for audio?
Technology is earphones (HM) or speakers (RM) with audio boards
What are the algorithms for generation in audio?
Sound modeling
What are the algorithms for rendering in audio? [2]
1. Binaural synthesis
2. Cross-talk cancellation
What are the algorithms for global effects in audio?
Room acoustics
What are the human factors for haptic?
Human factors are tactile force receptors
What is the technology for haptic?
Technology is body or ground mounted devices
What are the algorithms for generation in haptic?
Force modeling
What are the algorithms for rendering in haptic?
Virtual proxy rendering
What are the algorithms for global effects in haptic?
Multi-contact haptics
What is the definition of photometry?
Science of measuring light thus waves of 380nm to 780nm
Name the units used in photometry? [6]
1. Luminous energy
2. Luminous flux [Lumen, lm]
3. Solid angle [Steradiant, sr]
4. Illuminance [Lux, lx]
5. Luminous intensity [Candela, cd]
6. Luminance [nits]
What are the characteristics of luminous energy? [2]
1. Called “Lichtmenge”
2. lm*s
What are the characteristics of luminous flux? [5]
1. Called “Lichtstrom”
2. Different values have same radiant flux // Radiometry
3. Monochromatic Phiv = Km*Phie*V(lambda) // Km=683lm/Watt
4. Polychromatic Phiv = Km*int380nm780nm[Phie,lambda(lambda)*V(lambda)*dLambda]
5. Weighted with luminosity function
What are the characteristics of solid angle? [2]
1. Called “Raumwinkel”
2. Omega = A/r²
What are the characteristics of illuminace? [4]
1. Called “Beleuchtungsstärke”
2. lm/m
3. Clarity on surface
4. Decreases quadratically with distance to light source
What are the characteristics of luminous intensity? [5]
1. “Lichtstärke”
2. lm/sr
3. Candle has 1cd = (12 lm)/(4*pi sr)
4. Intensity of light source in specific direction
5. Independent of light source
What are the characteristics of luminance? [3]
1. Called “Leuchtdichte”
2. lm/m*sr
3. Perceived brightness of light source
What are the critical quality criteria of HMDs? [6]
1. Resolution
2. Field of view (FoV)
3. Lens distortion with Barrel (||) and Pincushion )||(
4. Screen door effect // Raster
5. Ergonomics
6. Integrated tracking system
How large is the size of the oval shape of FoV?
+-90° horizontal, +50°-70° vertical
How large is the size of the stereoscopic or binocular field of FoV?
100°-120°
Name different FoV and FoR 3DS definitions? [4]
1. Gesichtsfeld-FoV 3DS with fixed head and eyes
2. Blickfeld-FoV 3DS with fixed head and moving eyes
3. Blickfeld-FoR 3DS with moving head and eyes
4. Sichtfeld-FoV 3DS spanned by optical instrument
What are the critical quality criteria of RMDs? [6]
1. Resolution
2. Field of regard (FoR)
3. Screen door effect // Raster
4. Ergonomics
5. Tracking system
6. Costs, footprint, maintenance
Name different RMDs? [6]
1. PowerWall with edge blending (EB) of multiple projectors
2. Tiled displays
3. Table rear projection with bench and L-bench with additional vertical screen
4. Cave with smaller pixels → better projectors
5. Curved displays
6. Reality deck
What are the characteristics of hard edge blending for RMDs? [2]
1. Pixel-perfect alignment of projectors necessary
2. Discontinuities destroy illusion of presence
What are the characteristics of soft edge blending for RMDs? [3]
1. Same part of images projected from two adjacent projectors
2. Combined by gradually decreasing luminance
3. Also two dimensional possible
When have stereo techniques already been used?
By movie theater in LA (1922)
What are the characteristics of passive stereo techniques? [4]
1. L and R filter are orthogonal
2. Permanent projection of both views
3. No flipping and shutter
4. INFITEC
What are the characteristics of active stereo techniques? [3]
1. Time multiplex
2. Infrared stereo emitter
3. Shutter glasses with markers for opto-electro tracking
What is the idea of a stereo emitter in stereo techniques? [2]
1. Synchronization of glasses and graphics HW
2. For time interval one projector sends black other picture
What are the characteristics of ghosting in stereo techniques? [2]
1. Faded version of image is perceived by wrong eye
2. By design not possible for HMDs // Two screens
