Interactive shading of 2.5D models

Abstract

Advances in computer-assisted methods for designing and animating 2D artistic models have incorporated depth and orientation cues such as shading and lighting effects. These features improve the visual perception of the models while increasing the artists' flexibility to achieve distinctive design styles. An advance that has gained particular attention in the last years is the 2.5D modeling, which simulates 3D rotations from a set of 2D vector arts. This creates not only the perception of animated 3D orientation, but also automates the process of inbetweening. However, previous 2.5D modeling techniques do not allow the use of interactive shading effects. In this work, we tackle the problem of providing interactive 3D shading effects to 2.5D modeling. Our technique relies on the graphics pipeline to infer relief and to simulate the 3D rotation of the shading effects inside the 2D models in real-time. We demonstrate the application on Phong, Gooch and cel shadings, as well as environment mapping, fur simulation, animated texture mapping, and (object-space and screen-space) texture hatchings.