This presentation describes recent developments in the implementation of a virtual environment workstation in the Aerospace Human Factors Research Division of NASA's Ames Research Center. Introductory discussions are presented on the primary research objectives and applications of the system and on the system's current hardware and software configuration. Principle attention is then focused on unique issues and problems encountered in the workstation's development with emphasis on its ability to meet original design specifications for computational graphics performance and for associated human factors requirements necessary to provide compelling sense of presence and efficient interaction in the virtual environment

Bolas, M.

Bryson, S.

Coler, C.

Dasaro, D.

Fisher, Scott S.

Jacoby, R.

Kerr, D.

Mcdowall, I.

Stone, P.

Wenzel, Elizabeth M.

English

NASA Technical Reports Server

N95- 14034
THE AMES VIRTUAL ENVIRONMENT WORKSTATION:
IMPLEMENTATION ISSUES AND REQUIREMENTS
\
\
J
S. Fisher, R. Jacoby, S. Bryson, P. Stone, I. McDowaU, M. Bolas, D. Dasaro, E. Wenzel,
C. Coler, and D. Kerr
NASA Ames Research Center
Moffett Field, California
This presentation describes recent developments in the implementation of a Virtual Environment
Workstation in the Aerospace Human Factors Research Division of NASA's Ames Research Center.
Introductory discussions are presented on the primary research objectives and applications of the
system and on the system's current hardware and software configuration. Principal attention is then
focused on unique issues and problems encountered in the workstation's development with emphasis
on its ability to meet original design specifications for computational and graphics performance and
for associated human factors requirements necessary to provide compelling sense of presence and
efficient interaction in the virtual environment.
1. Research Objectives and Applications
In the Aerospace Human Factors Research Division of NASA's Ames Research Center, an inter-
active Virtual Environment Workstation (VIEW) has been developed to aid in design, simulation and
evaluation of advanced data display and management concepts for operator interface design. The
VIEW system provides a virtual auditory and stereoscopic image surround that is responsive to
inputs from the operator's position, voice and gestures. As a low-cost, multipurpose personal simu-
lation device, this variable interface configuration allows an operator to virtually explore a
360-degree synthesized or remotely sensed environment and viscerally interact with its components.
At present, the major thrust of this research effort centers on the development of guidelines and
requirements that are necessary for implementation of virtual environments that are matched as
closely as possible to human cognitive and sensory capabilities and that feature transparent, natural
system interaction. It is projected that design specifications derived from this prototype system can
help define the range of necessary and sufficient hardware and software architectures for future vir-
tual environment systems.
Application areas of the virtual environment research are focused in:
TELEPRESENCE: Development of workstations for complex operational tasks such as teler-
obotic and telepresence control of remotely operated robotic devices and vehicles that require a suf-
ficient quantity and quality of sensory feedback to approximate actural presence at the task site.
DATASPACE: Development of concepts and guidelines for "portable" multi-modal information
management systems such as EVA Spacesuit visor display, with subsequent development of work-
stations for supervision and management of large-scale integrated information systems in which data
manipulation, storage and retrieval, and system monitoring tasks can be spatially organized.
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VISUALIZATION: Designandevaluationof virtual environments to facilitate visualization of
complex, three-dimensional data structures in areas such as architecture, engineering and computa-
tional fluid dynamics, and for interactive training or planning environments such as surgical
simulation.
2. VIEW System Configuration: Performance requirements and implementation
The current Virtual Interface Environment Workstation consists of: a wide-angle stereoscopic
display unit, glove-like devices for multiple degree-of-freedom tactile input, connected speech
recognition technology, gesture tracking devices, 3D auditory display and speech-synthesis technol-
ogy, and real-time computer graphic and video image generation equipment. This hardware is inte-
grated with a realtime Unix workstation that supports the computations required to drive an external
high-performance realtime 3D graphics system, processes input from up to 12 realtime input periph-
erals (e.g., the trackers and gloves), and provides other realtime task processing. A collection of
software called the "simulation framework" has also been developed that consists of a well-docu-
mented library of functions to provide access to all of the system peripherals and software services,
and of a collection of source files and simulation software that demonstrates the use of the major
hardware and software components that make up the VIEW system in order to facilitate system
reconfiguration for changing research requirements.
Before the beginning of the implementation phase of the Virtual Environment Workstation, a
number of performance requirements and specifications for the major VIEW systems components
were determined. These are discussed with respect to attaining an overall performance objective of
providing 640x480 pixel resolution imagery at 30 frames per second over dual, independent, syn-
chronized display channels with image viewpoints updated in coordination with head and limb
motion.
3. VIEW Implementation: Unique Issues and Problems
The VIEW project attempts to match media and computational technology as closely as possible
to the perceptual and cognitive capabilities of the human operator in order to achieve a state of
Telepresence in which a sufficient quantity and quality of sensory feedback is presented to the opera-
tor to approximate presence at a remote task site or in a synthetic environment. The factors that
directly influence and effect the achievement of this display configuration are divided into three
main areas and are discussed in detail as examples of problems and challenges for the development
of virtual environment systems.
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3.1 Computationalissues.
Problemsin achievingVIEW objectiveof 30Hzframerate:
- Overallcumulativesystemtransportdelay
- "Realtime"UNIX
- Communicationtiming problemsandschedulingartifacts
- Problemswith originalperformancebenchmarking
I/O problemsandrequirements:
- RS232 requirements and host modifications
- Parallel communication between host and graphics system
Floating point accuracy requirements in database representation.
System calibration requirements for research applications (tracker, etc.)
The need for evolution to object-oriented software structure for VIEW.
3.2 Graphics implementation issues:
Requirements and problems in synching dual channel graphics systems for proper
stereocopic image representation:
SGI IRIS graphics
HP SRX/TurboSRX graphics
ISG graphics
Differences between human eye and virtual camera image geometry:
Viewport specification
Perspective transformations (world rotation)
Field of View specification
Display calibration requirements
Matrix/Euler/Quatemian representation; difficulties and advantages.
Graphics language implementations and extensions (GOSAMR)
- Object editor
- Problems with animating textures
- Needed extensions
Idiosyncrasies of lighting model in VIEW environment.
Software structure for 3D information windows in VIEW environment: differences
between screen space and world space.
3.3 Human Factors issues (Telepresence requirements):
Guidelines and requirements necessary to provide stereoscopic images that are
geometrically correct representations of the depth relationships and perspective of a
rendered or captured scene are discussed (orthostereoscopy). For example, in an
orthostereoscopic scene, an object in the Virtual Environment would subtend the same
angle of visual field as the object it represents in the real world and would also impart
correct motion parallax and motion perspective cues in relation to its virtual
surroundings as the viewer changes position.
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Differencesbetweenhumaneye and virtual camera image geometry are discussed with
reference to view representation, depth of field representation, image separation for
stereoscopic fusion, window effect in stereoscopic image fusion, foveal image display,
and correct focal length and viewport specification.
Differences between human eye and virtual camera image QUALITY such as
luminance, resolution, color, and texture are discussed as well as differences between
human visual system and virtual camera image DYNAMICS such as frame rate and
image generation lag, axis of rotation for changing viewpoint (tracker offset), image
and spatial distortions from non-parallel optical axes, and infinity optics versus variable
accomodation performance.
Multisensory virtual representations provide an additional dimension to the
telepresence experience and are discussed in relation to synchronization with visual
imagery, auditory localization and 3D sound cues, tactile feedback, and visceral
simulation with motion platforms.
4. References
Fisher, Scott S. (1968) "Telepresence Master Glove Controller for Dexterour Robotic End-Effec-
tors," Advances in Intelligent Robotics Systems, D. P. Casasent, Editor, Proc. SPIE 726, 1986.
Fisher, S. S., McGreevy, M., Humphries, J., Robinett, W., (1968) "Virtual Environment Display
System," ACM 1986 Workshop on 3D Interactive Graphics, Chapel Hill, North Carolina.
October 23-24, 1986.
Fisher, S. S., McGreevy, M., Humphries, J., Robinett, W. (1987) "Virtual Interface Environment for
Telepresence Applications," J. D. Berger, Editor, Proceedings of ANS International Topical
Meeting on Remote Systems and Robotics in Hostile Environments, 1987.
Fisher, S. S., Wenzel, E. M., Coler, C., McGreevy, M. W., (1988) "Virtual Interface Environment
Workstations," Proceedings of the Human Factor Society 32nd Annual Meeting (October 24-28,
1988, Anaheim, California)
Foley, James D. (1987), Interfaces for Advanced Computing. Scientific American, 257 (4), 126-135.
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The Ames Virtual Environment Workstation: Implementation issues and requirements

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