Locally Developable Constraint for Document Surface Reconstruction

This article presents a global optimization approach to reconstruct surfaces from a single document image. Instead of assuming globally developable in previous works which restricted the surface to be cylindrical, conical, etc, we use a free form parametric model which is simple yet expressive enough in the reconstruction task. We then apply developable constraints locally on sample points from extracted feature curves. And in order to further achieve better stability, the developable constraint we put on it is not so strong. Instead of isometric or conformal constraints used frequently in surface parametrization tasks, we use orthogonality. We show that even this is enough to reconstruct a wide class of document surfaces even with an uncalibrated camera.