origins of virtual environments

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Origins of Virtual Environments S.R. Ellis, Origins and Elements of Virtual Environments, in Virtual Environments and Advanced Interface Design, Barfield and Furness, Oxford University Press, 1995, pp. 14-57 Summarized by Geb Thomas

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Origins of Virtual Environments. S.R. Ellis, Origins and Elements of Virtual Environments, in Virtual Environments and Advanced Interface Design , Barfield and Furness, Oxford University Press, 1995, pp. 14-57 Summarized by Geb Thomas. Learning Objectives. - PowerPoint PPT Presentation

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Page 1: Origins of Virtual Environments

Origins of Virtual Environments

S.R. Ellis, Origins and Elements of Virtual Environments, in Virtual Environments and

Advanced Interface Design, Barfield and Furness, Oxford University Press, 1995, pp. 14-57

Summarized by Geb Thomas

Page 2: Origins of Virtual Environments

Learning Objectives

1. Learn what VR is and how it works as a form of communication.

2. Understand the concept of virtualization including the differences between virtual space, a virtual image and a virtual environment.

3. Learn about the history of virtual environments and the important pioneers and forces that shaped its creation.

4. Understand the variety and types of hardware used in VR. 5. Learn about the types of tradeoffs that VR technology

requires, particularly cost versus performance, mass of gear to be worn, and resolution versus field of view.

Page 3: Origins of Virtual Environments

Communications and Environments VE’s are media, like books, movies or radio Task of scientists is to make interaction

with the media efficient and effortless -- reduce the adaptation period

VE extends the desktop metaphor to 3D. Historically this uses physical constraints

from simulator and telerobotics fields

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Components of VE

Content

Geometry

Dynamics

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Content

Objects and actors described by characteristic vectors (a total description of each element) and position vectors (a subset of character vectors).

Self is a special actor representing point of view

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Geometry

Dimensionality– Number of independent descriptive terms needd to

specify the position vector

Metrics– Rules applied to the position vector to establish

order

Extent– The range of possible values for the position vector

Page 7: Origins of Virtual Environments

Dynamics

Rules of interaction of the content elements

Example, the differential equations of Newtonian dynamics.

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Our Sense of Physical Reality

We construct reality from symbolic, geometric and dynamic information directly presented to our senses

Generally we see only a small part of the whole. We rely on a priori knowledge We are predisposed to certain arrangements of

information -- we resonate with some more than others.

Page 9: Origins of Virtual Environments

Virtualization

The process by which a human viewer interprets a patterned sensory impression to represent an extended object in a n environment other than that in which it physically exists.

Three levels:– Virtual space– Virtual image– Virtual Environment

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Virtual Space

Perceived 3D layout of objects in space when viewing a flat screen– perspective

– shading

– occlusion

– texture gradients

This must be learned! False cues Perceived size or scale is not inherent in media

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Virtual Image

The perception of an object in depth with accommodative, vergence and (optionally) stereoscopic disparity cues are present.

Scale not arbitrary

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Virtual Environment

Add observer-slaved motion parallax, depth of focus variation and wide field-of-view without visible restriction of the field of view

vergence accommodative vergence - reflective change in

vergence caused by focus adjust. optokinetic reflex - eye tracking objects vestibular-ocular reflex - eye tracking head

Page 13: Origins of Virtual Environments

Virtual Environments (cont)

“Measurements of the degree to which a VE display convinces its users that they are present in the synthetic world can be made by measuring the degree to which these responses can be triggered in it.”

Device calibration and timing are critical. The sensory systems can often adjust to systematic distortion, but not to time lags.

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Viewpoints

Egocentric -- see the world from viewer’s point of view

Exocentric -- see the user acting in the world

Similar to inside-out and outside-in frames in aviation literature

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Origins of VE

Human fascination with vicarious experience– cave art– Through the looking glass– Computer games– Neuromancer (Gibson)

Ivan Sutherland stereo display Myron Krueger’s VIDEOPLACE U. of Illinois’ CAVE

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Vehicle Simulation

Much VE derived from aircraft and ship simulators

Development of special purpose machines: matrix multipliers -- graphic pipelines, graphic engines

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Moving Simulators

Motion sickness Subthreshold visual-vestibular mismatches

to produce illusions of greater freedom of movement “washout”

Understand dynamic limits of visual-vestibular miscorrelation

Page 22: Origins of Virtual Environments

Cartography

Controlled information distortion– spherical projection– vertical scale exaggeration

VE’s can enhance presentation with graticules to help avoid effects of distortion.

Combine images to make virtual maps

Page 23: Origins of Virtual Environments

Applications

Scientific and medical visualization– multiple time functions of force and torque on

manipulator or limb joints– Volumetric medical data– Electronic dissection– Architectural Walk-throughs

Page 24: Origins of Virtual Environments

Telerobotics

Predated many VR technology Spurred position tracking

technology– Polhemus system– accelerometers– optical tracking– acoustic systems– mechanical systems

Page 25: Origins of Virtual Environments

Telerobotics II

Input devices – Isotonic (significant travel)– Isometric (sense force and torque)

Force feedback devices– high electro-mechanical bandwidth– Can create instabilities– Utah/MIT Hand

Page 26: Origins of Virtual Environments

Photography, cinematography, viceo technology

The LEEP optical system, originally for stereo video used in VR stereo viewers

Sensorama, Morton Heilig (1955) Interactive video map (MIT 1980)

Page 27: Origins of Virtual Environments

Engineering Models Tendency to overplay successes and suggest greater

generality than exists Most helmet-mounted displays make users legally blind We need to understand characteristics of

– human movement– visual tracking– vestibular responses– grasp– manual track– time lags

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VE: Performance and Trade-Offs Performance Advances Stereoscopic visual strain Resolution/field-of-view tradeoff Appropriate application areas:

– multiple, simultaneous, coordinated, real-time foci of control

– Manipulation of objects in complex visual environments and require frequent, concurrent changes in viewing position

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Learning Objectives

1. Learn what VR is and how it works as a form of communication.

2. Understand the concept of virtualization including the differences between virtual space, a virtual image and a virtual environment.

3. Learn about the history of virtual environments and the important pioneers and forces that shaped its creation.

4. Understand the variety and types of hardware used in VR. 5. Learn about the types of tradeoffs that VR technology

requires, particularly cost versus performance, mass of gear to be worn, and resolution versus field of view.

Page 32: Origins of Virtual Environments

For Friday

Read the NRC Report, especially 13-24 and 35-66. Skim the rest

Personally, I think the recommendations are very interesting, because they reveal how a panel of scientists think of what research is important. Depending on where you are in your career, however this may not be so key.

Start drafting your essay. I want to see complete, supported ideas, not stream-of-consciousness!

Page 33: Origins of Virtual Environments