Shape Perception in 3-D Scatterplots Using Constant Visual Angle Glyphs

When viewing 3-D scatterplots in immersive virtual environments,
one commonly encountered problem is the presence of clutter,
which obscures the view of any structures of interest in the visualization.
In order to solve this problem, we propose to render the
3-D glyphs such that they always cover the the same amount of
screen space. For perceptual reasons, we call this approach constant
visual angle glyphs, or CVA glyphs. The use of CVA glyphs
implies some desirable perceptual consequences, which have not
been previously described or discussed in existing literature: CVA
glyphs not only have the prospect of dealing with clutter, but also
the prospect of allowing for a better perception of the continuous
shapes of structures in 3-D scatterplots. In a formal user evaluation
of CVA glyphs, the results indicate that such glyphs do allow
for better perception of shapes in 3-D scatterplots compared to regular
perspective glyphs, especially when a large amount of clutter
is present. Furthermore, our evaluation revealed that perception of
structures in 3-D scatterplots is significan