Finding coordinates of a triangle Mesh

Question

I have a triangle mesh and look for a way to get programmatically for a given (x,z) 2D point all y coordinates which are represented by the mesh (x,y1,z),(x,y2,z) ..., preferable in python. I have the mesh stored in one of the common file formats (.stl , .obj ...)

The problem behind this question is that i convert a 2D face image into a 3D mesh of the face (using the marvelous https://github.com/sicxu/Deep3DFaceRecon_pytorch project) and then want to map the depth information of the 3D model back to the 2d image (to build something fancy in blender ...)

Answer 1

I finally found a solution for the problem which is both slow and inelegant but does the job for me for now.

I use section_multiplane function of the trimesh python library for that. Basically i use this function to intersect the mesh with 2d planes parallel to the y,z-plane and calculate the depth values by analyzing the resultant 2D Path. The library is very fast in calculating the intersections but the part i wrote - extracting the depth information from the 2D Paths - is painfully slow right now. (which doesnt matter in my particular application)

The code for that I have now is deeply interwoven in my particular application so it doesn't make sense to share it but if someone is interested in this approach there is a very helpful example included in the trimesh library which covers the crucial points: section_multiplane example

I am sure there are much more elegant solutions for this problem available but I wanted to share this approach in case somebody struggles finding a better approach too ...

Heatmap displaying the extracted depth information:

depth info: