Visualizing multiple fields on the same surface

A long-standing problem in the field of visualization is the ability to display many overlaid data sets. Researchers have developed successful techniques that show multiple 3D fields by layering sparse similar glyphs. My colleagues and I at the University of North Carolina have investigated this problem for a number of years. Our driving application has been the display of data sets from scanned-probe and scanned-electron microscopes, which led us to concentrate on the display of multiple scalar fields. Although several of our first approaches were initially successful, they failed to scale to more than three or four data sets. So that others will not be tempted to follow the same course, I begin by presenting the argument for, preliminary successes with, and reasons for the eventual downfall of our initial approach. I then describe the key concept that enables successful techniques.