Hi @gari.kun
Several years ago at f+p, we developed a tool for volumetric space frame structural optimization, inspired by bone adaptation, and using ellipsoid packing in Kangaroo.
The sizing, alignment and anisotropy of the ellipsoids came from a stress field (found with COMSOL).
(This was done together with Alessandro Felder, who was doing a PhD at the time, co-supervised by f+p and the Royal Veterinary College).
There we were looking at packing them within a volume, but the same could be applied when keeping them on a surface without a lot of change.
The code is all open source. Because it relies on external software to calculate the initial volumetric stress analysis, and tetgen for the tetrahedralization of the points after the packing, it takes a bit of work to get it all up and running, but if you were looking to develop something similar there are probably parts that could be useful, such as the ellipsoid collision Kangaroo goal here.
We used the stress tensor sampled on a cubic grid. If you’re working with stress values on a mesh, then this interpolation part would need to be a bit different.