View-dependent geometry

Abstract

When constructing 3D geometry for use in cel animation, the reference drawings of the object or character often contain various view-specific distortions, which cannot be captured with conventional 3D models. In this work we present a technique called View-Dependent Geometry, wherein a 3D model changes shape based on the direction it is viewed from. A view-dependent model consists of a base model, a set of key deformations (deformed versions of the base model), and a set of corresponding key viewpoints (which relate each 2D reference drawing to the 3D base model). Given an arbitrary viewpoint, our method interpolates the key deformations to generate a 3D model that is specific to the new viewpoint, thereby capturing the viewdependent distortions of the reference drawings.