Improved Face Shape Recovery and Re-illumination Using Convexity Constraints
This paper describes work aimed at developing a practical scheme for face analysis using shape-from-shading. Existing methods have a tendency to recover surfaces in which convex features such as the nose are imploded. This is a result of the fact that subtle changes in the elements of the field of surface normals can cause significant changes in the corresponding integrated surface. To overcome this problem, in this paper we describe a local-shape based method for imposing convexity constraints. We show how to modifying the orientations in the surface gradient field using critical points on the surface and local shape indicators. The method is applied to both surface height recovery and face re-illumination, resulting in a clear improvement.
- 2.Besl, P.J., Jain, R.C.: Invariant surface characteristics for 3-d object recognition in range images. In: Comput. Vision Graphics Image Proc., vol. 33, pp. 33–80 (1986)Google Scholar
- 4.Forsythe, D., Ponce, J.: Computer Vision: a Modern Approach. Prentice-Hall, Englewood Cliffs (2001)Google Scholar
- 6.Horn, B.K.P., Brooks, M.J.: Shape from Shading. MIT Press, Cambridge (1989)Google Scholar
- 8.Prados, E., Faugeras, O.: A rigorous and realistic Shape From Shading method and some of its application. INRIA Research Report, RR-5133 (March 2004)Google Scholar