The following shows a wavy surface that is shaded with a grid texmap and a color scale that shows the Gaussian, Mean, Max and Min curvatures of the surface. The color scheme is abitrary, but such images can reveal hidden flaws of a NURB surface such as isoparams that back track on themselves:
The shader showk.sl takes a parameter to identify the type of curvature to display. Set the string CurvatureType to one of the following: gaussian, mean, min, max, ku, or kv. The default is "gaussian" curvature.