Patch-based Surface Relaxation

Fernando de Goes, William Sheffler, Michael Comet, Alonso Martinez, Aimei Kutt


From rigging to post-simulation cleanups, surface relaxation is a widely used procedure in feature animation. Over the years, Pixar has experimented with several techniques for this task, mostly based on variants of Laplacian smoothing. Notably, none of existing approaches are suited to reproduce the patch layout of a baseline mesh. This is of particular interest for modeling the span of edge flows, or for restoring the rest configuration of a mesh under large deformations. To achieve this goal, we developed a new patch-aware relaxation method for general polygonal meshes. Our approach encompasses three main contributions. We first introduce a weighting scheme that uses local decal maps to encode the structure of edge flows formed by the desirable patch layout. We then propose an update rule that transfers a reference patch arrangement to a deformed mesh. To control volume preservation, we also present a surface-constrained regime that exploits decal maps to slide points within the surface. We demonstrate the effectiveness and versatility of our tool with a series of examples from Pixar's short Bao and feature film Incredibles 2.

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