On the Benefits of Using Constant Visual Angle Glyphs in Interactive Exploration of 3D Scatterplots

Abstract

Visual exploration of clouds of data points is an important application of virtual environments. The common goal of this activity is to use the strengths of human perception to identify interesting structures in data, which are often not detected using traditional, computational analysis methods. In this article, we seek to identify some of the parameters that affect how well structures in visualized data clouds can be identified by a human observer. Two of the primary factors tested are the volumetric densities of the visualized structures and the presence/absence of clutter around the displayed structures. Furthermore, we introduce a new approach to glyph visualization—constant visual angle (CVA) glyphs—which has the potential to mitigate the effect of clutter at the cost of dispensing with the common real-world depth cue of relative size. In a controlled experiment where test subjects had to locate and select visualized structures in an immersive virtual environment, we identified several significant results. One result is that CVA glyphs ease perception of structures in cluttered environments while not deteriorating it when clutter is absent. Another is the existence of threshold densities, above which perception of structures becomes easier and more precise.