Stochastic Microgeometry for Displacement Mapping Craig Schroeder

Distributions on a Surface Create the appearance of complex geometry Don’t want to store all that information Want to create multiple instances that are not identical but look similar Don’t want the patterns, boundary artifacts, repeated appearance, or distortion of textures

The Algorithm Convert the two distributions into a two-sided distribution. Use the number of triangles to make into a histogram. Consider the histogram bins one by one, starting from the outermost, working towards the innermost and ending with bin 0. When processing each bin, identify triangles that must have values from that bin Empty bin by placing randomly throughout the mesh

Displacement Mapping Takes the labels assigned to triangles in the previous slide Converts these labels into changes in geometry Calculate normal for each vertex by averaging normals from surrounding triangles Give each vertex a label by averaging the labels of the surrounding triangles Apply some function of that label (one function for negative labels, another for positive labels) to get an offset factor for each vertex Multiply the offset factor by the vertex normal to obtain an offset vector Add this vector to the original position to obtain the final position of that vertex.

Results