Quantifying the Relative Roles of Shadows, Stereopsis, and Focal Accommodation in 3D Visualization

M. Bailey, T. Rebotier, an D. Kirsh (USA)


Perception, three dimensions, shadows, stereopsis, virtualreality, augmented reality.


The goal of three-dimensional visualization is to present information in such a way that the viewer suspends disbelief and uses the screen imagery the same way as he or she would use an identical, real 3D scene. To do this effectively, programmers employ a variety of 3D depth cues. Our own anecdotal experience says that shadows and stereopsis are two of the best for visualization. The nice thing is that both of these are possible to do in interactive programs. They sacrifice a certain amount of interactive speed, but they are possible. But, there is very little information detailing exactly what these cues add to the perception process. The purpose of this project was to quantify how worthwhile using these two depth cues are, that is, is it worth losing interactivity to get them? Using a large number of student subjects, we performed a series of depth-test trials and analyzed the results. Finally, as an upper-bound control on these experiments, we also ran subject trials on physically fabricated 3D objects, viewing them through a pinhole in a controlled-lighting situation to factor out both shadows and stereopsis, leaving only focal accommodation. This paper shows the design of the experiments and the results expressed in reaction times and error rates. The results have a significant bearing on the design of 3D interactive visualization systems, particularly those that use virtual or augmented reality.

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