HFE 760 Virtual Environments Winter 2000 Jennie J. Gallimore

HFE 760 Virtual Environments Course Objective u To acquire an understanding of human factors issues and problems related to the development of virtual environment systems. u By the end of the quarter students will have: –an understanding of VE technologies, –understanding of research needs and issues, –experience creating a VE –experience conducting a VE research project

Introduction/Definitions u What is a virtual environment?

Definitions (from Chapter 1) u Virtual Environment - representation of a computer model (or database) that can be manipulated in an interactive way by participants. u Virtual Image - visual, auditory, tactile and kinesthetic stimuli conveyed so that they appear to originate from a 3- D space surrounding the participant. u Virtual Interface - System of transducers, signal processor, hardware, software creating an interactive medium to –1) convey information to senses, –2) monitor the psychomotor and physiological behavior of participant.

Typical interface - Desktop metaphor u To interact requires three cognitive models –1) model of immediate environment. –2) model of functionality of medium (e.g. Monitor and keyboard). –3) model of the message and it's heuristics conveyed through the medium.

Immersed VE u We become part of the message, draw on a single model of the new environment. Given we are in the environment, should be able to use natural semantics as if interacting with physical world.

Ideal Medium u Should be configured to match sensory and perceptual capabilities of humans and the message should be organized to achieve a match between human's mental model of the system and machine interpretation and representation of that system. u Table 1-1 (p7) provides examples of attributed of an ideal medium.

Issues and Problems (Pg. 11) u Theoretical basis for work in VE, develop conceptual models to assist designers of virtual worlds. u Solid understanding of human factors design implications. u Development of dependent measures to determine goodness of VEs. u Physiological and behavior tracking of participants.

Issues and Problems Cont. (Pg. 11) u Affordable, light weight systems. u Hardware architecture, rapid image generation methods, u Software infrastructure and tools for constructing, managing, interacting in VE. u Need for languages, spatial and state representations, and interactive heuristics for constructing virtual worlds.

Three Components of an Environment (Ellis, Chapter 2) u Content u Geometry u Dynamics

Content u Object and actors - described by characteristic vectors (position, orientation, velocity, acceleration, color, texture, energy) i.e. a description of the properties of the objects. The characteristics that are common to all objects and actors is called the position vector. u Actors - are different from objects in that they have the capacity to initiate interactions with objects. Actors store energy of information and control the release of the energy or information after a period of time. –Examples : Self - provides a point of view from which the environment may be constructed. –E.g. balls on a billiard table are content (objects) and the cue is an actor.

Geometry u Dimensionality - number of independent descriptive terms needed to specify the position vector for every element in the environment (e.g. where, when, color, etc..) u Metrics- systems of rules that may be applied to the position vector to establish order, and the concept of geodesic (or loci of minimal distance) paths between points in the space. (E.g. Minimum distance between objects/actors) u Extent - range of possible values for the elements of the position vector. (E.g. if color is a characteristic of the position vector, what is the possible range of colors?)

Dynamics u Rules of interaction among contents describing behavior as energy or information is exchanged. –E.g. (Equations for swing the golf club or baseball bat given current states)

Virtualization (ELLIS) u "the process by which a human viewer interprets a patterned sensory impression to represent an extended object in an environment other than that in which it physically exists" –E.g. virtual image in optics

Levels of virtualization u virtual space - viewer perceives a 3-D layout when viewing a flat surface u virtual image - perception of an object in depth in which accommodative, vergence, and stereoscopic disparity are present, but not necessarily consistent u virtual environments - added elements of observer-slaved motion parallax, depth of focus variation, wide field-of- view. Synthesized to provide stimulation of psychological and physiological reflexes.

Viewpoints u Egocentric - sensory environment is constructed form viewpoint of the user (compensatory) u Exocentric - environment is viewed from a position other than where the user is (e.g. Bird's eye view, secondary viewer so can see yourself in the world) (pursuit)