Technical illustration based on human-like approach

Presents a human-like, non-photorealistic rendering approach. A typical process of how human engineers learn to paint a technical illustration is as follows. First, they are trained in how to paint separate primitives, such as cubes and spheres, and accordingly accumulate empirical drawing principles and skills during their continuous practice, and finally they can freely express complicated shapes by composing the related primitives' drawings together. We manage to mimic this human-like approach by embedding established illustration rules into primitives' lighting models and drawing algorithms, and implement it in an illustration system called RETOUCH.