IRIT- Universite ́ de Toulouse

Shading appearance in illustrations, comics and graphic novels is designed to convey illumination, material and surface shape char-acteristics at once. Moreover, shading may vary depending on dif-ferent configurations of surface distance, lighting, character expres-sions, timing of the action, to articulate storytelling or draw atten-tion to a part of an object. In this paper, we present a method that imitates such expressive stylized shading techniques in dynamic 3D scenes, and which offers a simple and flexible means for artists to design and tweak the shading appearance and its dynamic behav-ior. The key contribution of our approach is to seamlessly vary appearance by using a combination of shading primitives that take into account lighting direction, material characteristics and surface features. We demonstrate their flexibility in a number of scenar-ios: minimal shading, comics or cartoon rendering, glossy and anisotropic material effects; including a variety of dynamic vari-ations based on orientation, timing or depth. Our prototype im-plementation combines shading primitives with a layered approach and runs in real-time on the GPU