On Methods of Computer Graphics for Visualizing Densities
Edward J. Wegman, Luo Qiang · Journal of Computational and Graphical Statistics · 2002
This article focuses on visualizing densities and density approximators. We develop the relationship between the isopleths, the gradient, and the surface normals for a density with two-dimensional support. We show that these form a trihedron. We also develop the algorithm for computing the surface normal for the isopleths of a density with three-dimensional support. With this information in hand, we discuss rendering and lighting models, contouring algorithms, stereoscopic display algorithms, and visual design considerations. We conclude with some examples and a discussion of our experiences in using rendering and lighting, transparency, stereoscopy, dynamic rotation, and dynamic thresholding techniques to visualize densities.