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Virtual Environments: Introduction
Anthony Steed Simon Julier Anthony Steed, Simon Julier
Department of Computer Science University College London http://www.cs.ucl.ac.uk/teaching/VE
Outline
- What are Virtual Environments?
– Working definition – Constituents of the environment
T h l i f VE
– What are the toolbox of parts?
- Describing and Measuring a VE
– Immersiveness – Levels of virtualisation – Presence
Defining Virtual Environments
- What are Virtual Environments?
– Working definition – Constituents of the environment
T h l i f VE
– What are the toolbox of parts?
- Describing and Measuring a VE
– Immersiveness – Levels of virtualisation – Presence
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Virtual Reality in the Early 90s
NASA Ames Photo Archive
Device-Driven Definitions of Virtual Environments
- Virtual Reality is electronic simulations of environments experienced via head
mounted eye goggles and wired clothing enabling the end user to interact in realistic three-dimensional situations. (Coates, 1992)
- Virtual Reality is an alternate world filled with computer-generated images that
respond to human movements. These simulated environments are usually i it d ith th id f i d t it hi h f t t h i visited with the aid of an expensive data suit which features stereophonic video goggles and fiber-optic data gloves. (Greenbaum, 1992)
- The terms virtual worlds, virtual cockpits, and virtual workstations were used to
describe specific projects.... In 1989, Jaron Lanier, CEO of VPL, coined the term virtual reality to bring all of the virtual projects under a single rubric. The term therefore typically refers to three-dimensional realities implemented with stereo viewing goggles and reality gloves. (Krueger, 1991, p. xiii) “Defining Virtual Reality: Dimensions Determining Telepresence”, Steueur, 1992
Device-Driven Definitions of Virtual Environments
User User Interface Devices Computer Synthetic Environment Real Environment This is what makes this a VE
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Limitations of Device-Driven Definition
- “VR” and “not-VR” systems are defined by
presence / absence of hardware alone
– Previous definitions highly image oriented
- Lack of theoretical dimensions for parameterising
characteristics of VR
– How can different VR systems be compared? – How can VR be compared with different media?
A VE is an Immersive, Mediated Communication Medium
User User Interface Devices Environment Synthetic Environment Real Environment Mediated Medium
Components of the Environment
Contents: Actors and Objects Geometry: Dimensions, Metrics and Extent Dynamics: Interaction Rules
“Virtual Environments and Environmental Instruments”, S. Ellis, 1996
Environment
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Contents
- Environment is made up of discrete items known
as objects and actors
Di t d id tifi bl – Discrete and identifiable – Described by property vectors
- Actors are objects that initiate interactions
- The self is a special kind of actor with a point-of-
view
Geometry
- Description of the environmental field of action
- Contains:
– Dimensionality: The degree of freedom of the position vector vector – Metric: The basic mathematical rules for defining order, distance, etc. – Extent: The range of possible values of the position vector
Dynamics
- These are the rules of interaction among the
contents
– Differential equations of Newtonian dynamics to Differential equations of Newtonian dynamics to describe kinematic and dynamic relationships – Grammatical rules for pattern-matched triggered actions
- For comfortable use, relationship between
proprioceptive information and sensory data requires consistency, predictability, and completeness
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VE Technologies
- What are Virtual Environments?
– Working definition – Constituents of the environment
T h l i f VE
– What are the toolbox of parts?
- Describing and Measuring a VE
– Immersiveness – Levels of virtualisation – Presence
Components of a VE System
- Display / Rendering System
- User Input
- Tracking
- Database - no time to talk about this
Visual Display Systems
Headmounted Display FishTankVR: VR on a Monitor Headmounted Display Headmounted Display
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CAVE = Cave Automatic Virtual Environment
Cruz-Neira, C., Sandin, D.J., DeFanti, T.A. (1993) Surround-Screen Projection- Based Virtual Reality: The Design and Implementation of the CAVE, Computer Graphics (SIGGRAPH) Proceedings, Annual Conference Series, 135-142.
Audio Display Systems
Spatialised Audio Headphones
Haptic Display Systems
CyberGrasp Phantom Cybe G asp Tactors
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Olfactory Display Systems
“Projection-Based Olfactory Display with Nose Tracking” Y. Yanagida, S. Kawato, H. Noma, A., and N. Tetsutani, IEEE VR 2004, Chicago
Galvanic Vestibular Response System User Input Devices
Cubic Mouse Wand CyberGlove
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Tracking Systems
Inside-Out hybrid camera inertial system Outside-In camera- based tracking system
Describing and Measuring VEs
- What are Virtual Environments?
– Working definition – Constituents of the environment
g
– What are the toolbox of parts?
- Describing and Measuring a VE
– Immersiveness – Levels of virtualisation – Presence
Why Study VEs?
- VEs are tools to try to maximise information
between the computer and user
– Responds to the user through 3D controls – Responds to the user through 3D controls – Possibly speech controlled
– High-fidelity surrounding graphics – High quality spatialised sound
- The input / output configuration needs to
maximise the information flow
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Optimising the Performance of a VE
- “I define a virtual reality experience as any
in which the user is effectively immersed in a responsive virtual world. This implies user dynamic control of viewpoint ” Professor dynamic control of viewpoint. - Professor Fred Brooks, UNC Chapel Hill, USA
- But what does “effectively immersed” mean?
Optimising the Performance of a VE
- The best performance occurs when:
– the user loses awareness of the real world props that support the perceptual illusions; and – Actions are successfully supported in the environment
- In other words, the user experiences presence
- Presence is achieved in several steps:
Immersion Virtualisation Presence
Immersion
- Immersion is a description of the technology
– Inclusive – sensory experience from VE only – Extensive – more sensory modalities – Surrounding – from all directions – Vivid – high fidelity – Egocentric – first person point of view – Plot – things are happening and the VE responds to the user – Proprioceptive match – between sensory data and proprioception
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Virtualisation
- Immersion supports the process of virtualisation
- Virtualisation – “the process by which a viewer
interprets patterned sensory impressions to represent objects in an environment other than that from which the impressions originate”.
Levels of Virtualisation
- Virtual Space – see a 3D object when looking
at something inscribed on a flat sheet
– Perspective cues, lighting, shading
- Virtual Image – perception of an object with
depth
– Stereo disparity
- Virtual Environment – perception of a
surrounding environment
– head-slaved parallax, accommodation and vergence, surrounding display
Virtual Space
Half-Life 2, Valve Software
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Virtual Image Virtual Environment
immersion because of the requirements for head- related and egocentric display
actively explore the (visual) environment by moving naturally
Some Presence Definitions
- ‘The sense of “being there”’ (Held & Durlach,
Sheridan, Zeltzer: premier issue of PRESENCE, 1992)
- ‘A perceptual illusion of nonmediation’ (Lombard and
Ditton 1997) Ditton, 1997)
- ‘A mental state in which a user feels physically
present within the computer-mediated environment’ (Draper & Kaber, 1998)
- ‘The subjective experience of being in one place or
environment, even when one is physically situated in another’ (Witmer & Singer, 1998)
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Presence Operationally
- Successful substitution of real sense data by
computer generated sense data
- ‘Successful’ – response is similar to expected
response in everyday reality response in everyday reality
– Low level physiological → high level cognitive and emotional – Includes verbal responses about ‘being there’ – Response includes potential for interaction
Impact of Virtual Environments
- Meehan, M., B. Insko, M. Whitton and F. P. Brooks Jr. (2002).
"Physiological Measures of Presence in Stressful Virtual Environments." ACM Transactions on Graphics 21(3): 645-652. (Proceedings of ACM SIGGRAPH 2002, San Antonio , Texas ).
Summary
- A working definition of VEs
– Mediated communication environments
- A very brief overview of the technology
behind virtual environments behind virtual environments
- Levels of virtualisation
- Critical role of immersion in affording
proprioceptively correct changes in sensors data
- Presence as the human response
