Given a 2D image of a human face and the corresponding 3D shape, how do I project the shape onto the images to extract texture patches from them to form a partial UV map?
I've accomplished this by positioning the mesh in a known position (such as the origin), placing the image in front of it so that from the camera's point of view they align as desired. Then it's simply a matter of shooting a ray from each polygon's vertices through the image towards the camera. Wherever the ray intersects the image, that's your
(u, v) point for that vertex.