levels of realism: from virtual reality to real virtuality - perception and virtual time
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Levels of Realism: From Virtual Reality to Real Virtuality - Perception and Virtual Time. Alan Chalmers † Andrej Ferko ‡ † Warwick Digital Laboratory, UK ‡ Comenius University, Slovakia. Courtesy of recomCGI and Steffen Schraegle, produced via SpheronVR Technology. “Holy Grail”. - PowerPoint PPT PresentationTRANSCRIPT
© 2006 WMG
© 2007 WMG
Levels of Realism: From Virtual Reality to Real
Virtuality - Perception and Virtual Time Alan ChalmersAlan Chalmers† Andrej Ferko Andrej Ferko‡
† Warwick Digital Laboratory, UKWarwick Digital Laboratory, UK‡ Comenius University, SlovakiaComenius University, Slovakia
2Warwick Digital LabWarwick Digital Lab© 2007 WMG
““Holy Grail”Holy Grail”
Realism in Real-Time Real-Time ≥ 25 fps
Realism …?
Courtesy of recomCGI and Steffen Schraegle, produced via SpheronVR Technology
3Warwick Digital LabWarwick Digital Lab© 2007 WMG
IntroductionIntroduction
Virtual reality
1960’s
• Morton Heilig’s Sensorama
• Ivan Sutherland’s head mounted display
Modern multi-modal VR systems
• CAVE’s, data-gloves, etc.
Needs real-time
Trade off realism to achieve this
GPUs make things faster
• Not physically based
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Types of realismTypes of realism
1998: Lengyel’s rendering spectrum
Images which are appearance based
Geometry which is physically based
2001: Ferwerda
Physical realism
• Visual simulation
Photorealism
• Visual response
Functional realism
• Visual information
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Physical realismPhysical realism
Exact match
Spectral irradiance values
Match at all points within the real and virtual scene
Scene modelled precisely
Geometry
Materials
Light transport
BUT
All include approximations
Especially displays (even HDR is only 3,000 cd/m2)
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PhotorealismPhotorealism
Resultant rendered image
Indistinguishable from photograph of real scene
Other forms
Lumigraph [Gortler et al. 1996]
Image based lighting [Debevec et al. 1996]
But
Make rendered images more like a photograph
Blurring
Increasing Gaussian noise
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Being thereBeing there
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Functional realismFunctional realism
Image provides
Sufficient information to enable viewer to complete task
Correct relative size and shape
But not material properties
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Levels of realismLevels of realism
One-to-one mapping
Virtual world to Real world experience
Adopt same learning strategy
Real and virtual worlds
High confidence in results
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Believable realismBelievable realism
Believable Realism!
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Scruffy texturesScruffy textures
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ClassificationClassification
Is PhysicsIP
Not PhysicsNP
Not BelievableNB
Is BelievableIB
Real virtuality
Photorealism
IBNP IBIP
NBNP NBIPAvatars
Uncanny valley
Cartoons NPR
Photographs
Games
Virtual Reality
Functional realism
Abstract art
Vermeer
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Comparing real and virtual scenesComparing real and virtual scenes
Physical test environment with diffuse materials
[Meyer et al. 1986]
Comparing photograph with real scene
[Rushmeier et al. 1995]
Visual Difference Predictor (VDP)
[Daly 1993], [Myszkowski 1998], [Mantiuk et al. 2005]
Karol’s new method
Myszkowski et al. @ SIGGRAPH 2008
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Holistic approachHolistic approach
Three different human visions
Monocular, binocular, and ambient
Four parallel processes
Head, eye, visual perception, cognitive processes
Visual equivalence
[Ramanarayanan et al. 2007]
Judgement of lightness
[McNamara et al. 2000]
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Multi-modalitiesMulti-modalities
Human perceives environment with all senses
Sight
Sound
Smell
Touch
Taste
Crossmodal effects can be considerable
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PresencePresence
Typically a measure of technical immersion
Higher quality more immersion
But
Immersion in books and films
Can quantify user’s engagement with VE
Not a measure of realism
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PreconditioningPreconditioning
Human imagination
Dungeons & Dragons
Virtual Vietnam
Habituation
Familiarity may make user perceive less
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Nature of taskNature of task
Top down process
Attention under volitional control
What we perceive is strongly dependent on the task
Looking for a street sign
Finding a coffee shop
On patrol in (hostile) environment
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There-realityThere-reality
Same perceptual response as if “there” in real world
Exploits limits of human perception
Only render in high quality what user is attending to
Selective rendering
Benefits from crossmodal interactions
Can save significant computational effort
Experience
Active – infinitive limited by technology
Passive
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The perception equationThe perception equation
Function of task (t) and preconditioning (ρ):
P(t, ρ) = ωv V + ωa A + ωs S + ωt T + ωf F
V=Visuals, A=Audio, S=Smell, T=Taste, F=Feel
Σωi = 1
ωi are threshold values
Above threshold there is no perceptual difference
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ExampleExample
Preconditioning
Experienced sailor
Sound of water across hull
Feel of wind on skin
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Other approachesOther approaches
Eg. Neurolinguistic programming (NLP)
Sensory input channels
Visual
Audio
Kinesthetic
Olfactory
Gustatory
Can be used to represent eg. desire, emotions …
Initially: Interpersonal communication model
Now: Business and management training
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Virtual time issueVirtual time issue
Perceptual equation re-read…
Sensory input channels in real and virtual time (Borges, 2 past)
Visual
Audio
Kinesthetic
Olfactory
Gustatory
Higher level of perception… VR as a semiotic system
How to define and measure interestingness?
Up to now: data mining, Koestler, engagement in virtual museums
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ConclusionsConclusions
In virtual reality striving to achieve
More realism
While maintaining real-time performance
Many applications don’t need physical realism
For those that do
May not be possible to compute total physical realism
Perceptual realism
• Same user response as if there in real scene being portrayed
• Can save significant computation by exploiting human perception
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ChallengesChallenges
Delivery system
Virtual cocoon (light weight, portable system)
Determine the “weights” ωi in the perception equation
Empirical studies
fMRI brain imaging
Weights are individual
Some generic similarity
Do NOT have to be determined precisely
As long as we are ABOVE the thresholdPerceptually high-fidelity virtual environments
Real virtuality
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AcknowledgementsAcknowledgements
Pavel Zemcik and MEMICS team for inviting
SCCG for enabling long-term discussions
EPSRC for funding “…towards Real Virtuality”
Alan’s group for 23 years of exciting research
David Howard + Christopher Moir + red wine Real Virtuality
Further details:
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Levels of Realism: From Virtual Reality to Real
Virtuality - Perception and Virtual Time Alan ChalmersAlan Chalmers† Andrej Ferko Andrej Ferko‡
† Warwick Digital Laboratory, UKWarwick Digital Laboratory, UK‡ Comenius University, SlovakiaComenius University, Slovakia