Benjamin Lok

University of North Carolina at Chapel Hill

lok@cs.unc.edu

Citation:

Lok, B. (2003) “Evaluation and Application of Algorithms for a Hybrid Environment System.” Energy, Simulation Training, Ocean Engineering and Instrumentation, Research Papers of the Link Foundation Fellows. Ed. Thompson, B., New York: University of Rochester Press, Vol. 3, 2003 (In Press).

Abstract:

Suppose one has a virtual model of a car engine and wants to use an immersive virtual environment (VE) to determine whether both a large man and a petite woman can readily replace the oil filter.  This real world problem is difficult to solve efficiently with current modeling, tracking, and rendering techniques.  Hybrid environments, systems that incorporate real and virtual objects within the VE, can greatly assist in studying this question.   In this paper we describe new algorithms for generating virtual representations, avatars, of dynamic real objects at interactive rates and enabling virtual objects to interact with and respond to the real-object avatars.  This allows dynamic real objects, such as the user, tools, and parts, to be visually and physically incorporated into the VE.  The algorithms use image-based object reconstruction and a volume-querying mechanism to detect collisions and to determine plausible collision responses between virtual objects and the real-time avatars.

We then evaluate the algorithms from various standpoints:

·        (Engineering) – We present an implementation of the reconstruction and collision detection algorithms in a prototype system

·        (Theoretical) – We conduct performance and error analysis for the algorithms.

·        (Usability) – Beyond theory though, are hybrid environments even practically useful for VE tasks?  We conducted a user study that evaluated the hybrid environments’ effect on VE task performance and sense-of-presence.

·        (Applicability) – We looked to evaluate hybrid environments in the context of a real-world task

The study showed that for spatial cognitive manual tasks, hybrid environments provide a significant improvement in task performance measures.  Also, participant responses show promise of improving sense-of-presence over customary VE rendering and interaction approaches. 

We detail our beginning collaboration with NASA Langley Research Center to apply the hybrid environment system to a satellite payload assembly verification task.  In an informal case study, NASA LaRC payload designers and engineers conducted common assembly tasks on payload models.  The results suggest that hybrid environments could provide significant advantages for assembly verification and layout evaluation tasks.

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Screenshot from our reconstruction system.  Note the correct occlusion between the participant’s hand (real)

and the teapot handle (virtual).

The user naturally interacting

with a cloth simulation.

What the participant saw. 

The real objects (pipe and cable) among

virtual objects (table and payload models).