We present a closed-form solution to the problem of recovering
the 3D shape of a non-rigid potentially stretchable
surface from 3D-to-2D correspondences. In other words,
we can reconstruct a surface from a single image without a
priori knowledge of its deformations in that image.
State-of-the-art solutions to non-rigid 3D shape recovery
rely on the fact that distances between neighboring surface
points must be preserved and are therefore limited to inelastic
surfaces. Here, we show that replacing the inextensibility
constraints by shading ones removes this limitation
while still allowing 3D reconstruction in closed-form.
We demonstrate our method and compare it to an earlier
one using both synthetic and real data.