Fig 3. Detailed overview of the procedural mesh processing (Fig 2f), which follows a series of automated steps to process the 'high poly' 3D mesh into a 'low poly' optimized mesh.

(a) Import: The mesh is imported, and its name and filepath is extracted for use during automation. Parameters affecting retopology and UV mapping can be modified during import; (b) Voxelize: To prepare for retopology, the mesh is filtered through a voxel grid that ensures uniformly-sized surface topology. This voxel-mesh is created at a higher resolution than the original, and projected onto the original surface to prevent distortion; (c) Retopology: The model's 'polycount,' or number of surface triangles, is reduced and optimized. This can either be according to predefined angle tolerance, or based on a predefined heatmap selecting areas of interest to be preserved at high-resolution; (d) Clean-up: Holes in the mesh, non-triangular and non-manifold geometry, and other topology errors are located and fixed; (e) UV map: UV coordinates can be created or "unwrapped" using a series of automatic projection methods, depending on the subject's shape. For most birds, we use 8 simultaneous planar projections placed according to the model's bounding box. This method uses Angle-Based flattening; (f) Export: The finished 'low-poly' mesh is exported and renamed according to the initial name and filepath.