Despite the current ubiquity of realistic computer-generated imagery, it is important to keep in mind the demand for editing capability. In Japanese animation, the use of hand-drawn images has long offered full artistic control. Regardless, storytelling purposes in the sense of dynamic, detailed scenes, but also budget and time constraints, are increasingly leading artists towards 3D content creation. Nevertheless, designers want to retain the traditional anime style.
One of the most important aspects of the toon look is the use of strokes to outline objects. This is frequently implemented as an image-space solution that compares attributes of neighboring samples. We propose a novel technique that compares samples on the fly by relying on a shared cache to prevent unnecessary attribute computations. This has both advantages and drawbacks over a post process, but better fits the constrained rendering environment that is used for our productions.
This project was implemented in C++ using the Autodesk Maya API, for the Arnold renderer.