I had tried faceshop years ago and it was not working well for me at all. It made grotesque monsters no matter what I tried :)  monstershop... back then i didn't understand why this was allowed to be in the daz shop.

anyways, a full head is too much ask for. i just want to reconstruct a few reference points for sculpting. single vertices are enough. coordinates of the eyes, ears, nose and a few more, the stable parts of the head.

i tried to read some papers, but its difficult, some of them are incomplete and stole their texts from other sources without citing them properly, so one cannot follow up. its complicated math, and i am not familiar with the matter. i understand there is a  projection matrix transforming 3d coordinates into 2d coordinates, and each photo has its own projection matrix because of camera position and rotation, but it it seems one cannot just formulate an equation system to solve, otherwise the papers had said so, i think. maybe its because of the 4d coordinate system, that one cannot apply the easy linear algebra methods.

there are big number cruncher programs for laser data, and also photo to mesh solutions, but it looks all incredible complicated and unprecise, they process the photos and through guessing algorithms at them, that will not work. just mark the key feature points on the images and reconstruct, this should work, i just do not know how :)

a projection matrix, is this invertable? it has a 4th dimension and I think this dimension has a special non linear function isn't it?