Interactive Geometry Decals

We present a novel real-time method for geometric displacement mapping on arbitrary 2-manifold triangle meshes. It is independent of the surface resolution and allows very fine geometric details to be added. We first compute a local surface parameterization using barycentric particle tracing and a constrained mass-spring system. This system satisfies the hard constraint of keeping all mass points on the surface. We propose a novel, entangled spring topology that is regularly 6-connected and has a chromatic number of 2. Therefore, the system can be efficiently solved on the GPU using a Gauss-Seidel solver. To render the displaced surface, we introduce a new GPU technique to cut out a surface patch at sub-pixel precision. The displacement mesh is then smoothly blended into the resulting opening. We show that our method overcomes common problems of displacement mapping such as limited resolution of the base surface and the need for a low-distortion global parameterization.