Methods for surface interrogation

The authors discuss various visualization techniques that have the goal of identifying unwanted curvature regions interactively on screen. The authors give a critical survey of surface interrogation methods. Several isoline and contouring techniques are presented, and the reflection line method, which simulates the so-called light cage by computer graphics, is presented. The isophote method analyzes surfaces by determining lines of equal light intensity. Silhouettes are special isophotes. A different approach to these problems is the mapping-technique. The mapping methods recognize unwanted curvature regions by detecting singularities of a special mapping of the curve or surface investigated. Curvature plots are a practical means of analyzing free-form surfaces. All these methods are effective, but generally need a lot of computational effort. The free-form surface visualization by ray tracing is discussed