Pixel Wise Pie Charts: Placement of Data Points Visualizing Spatial Value Distributions

Abstract

Handling overplotted points in spatial pixel-based visualizations is usually done either by aggregation or sampling. The third rather unusual alternative is replacing data items untangling overplotted regions. Depending on the placement algorithm visual artifacts will be created based on an optimization between overplotting, display usage, and conservation. In this paper, we exploit the replacement and create pixel-based pie-charts reflecting the numerical distribution of spatially referenced data points. With this novel approach, we bridge the gap between the overview and detail phase in Shneiderman's Information Seeking mantra. Our presented algorithm is informally evaluated with a biological case study on baboon movement.