“Interactive shade control for cartoon animation” by Shimotori, Nakajima, Sugisaki, Maejima and Morishima

Shade in traditional cel animation is an essential element and plays a symbolic role in the artistic portrayal of character and scene. The shade on a character’s face can be used to show emotion such as anger, sadness and hatred. Despite its usability, shade is relatively quickly or roughly drawn in animation for the following reasons. Firstly, cel animators require a large amount of time to draw shade. Secondly, because of the time requirements, producing complicated shade is expensive. On the other hand, 3D models enable users to more easily render or recreate shade than cel animation techniques. Consequently, 3D models are being gradually introduced into cartoon animation. Using Phong’s 3D shading model, however, shade is rendered too realistically for cartoon animation, and is therefore not appropriate for traditional-style cel animation. To solve similar problems with highlighting, Anjyo and Hiramatsu proposed a procedural method for designing stylized highlights [Anjyo and Hiramatsu 2003]. This concept has been applied to shade in our system.

1. K. Anjyo and K. Hiramatsu, “Stylized Highlights for Cartoon Rendering and Animation”, IEEE Computer Graphics and Applications, vol.23, No.4, pp.54–61, 2003.