Thanks for the tip and the good exercice. I took a look to this problem,
I used mesh instead of surface, so faces acts like pixels, I made a little C# in order to have the difference between two subsets. The list of face number (0 to n-1) and the list of faces intersecting the curves. All others component must be legacy Rhino.
It tooks
15 s with 32 000 points, length of 1
15 s with 120 000 points, length of 1
105 s with 962 000 points, length of 0.5
If you want to have a better representation of the patch, you can push their points to the curves around.
bundling_to_surface_LD.gh (3.5 MB)