Recovering 3D shape and texture from continuous focus series: using a polarized filter

An accurate method recovering the 3D object function g(X,Y,D) from an image sequence of continuous focus series is proposed. Not only the depth map D(x,y) but also a pan-focused brightness map g_p(X,Y) (a clear texture image observed by an ideal pinhole camera) are obtained. The depth map (2 1/2-D sketch) of the scene is evaluated by detecting that a distinct maximum of the point spread function exists in the focal plane. To estimate the maximum, a local variance of the brightness distribution is computed as a function of the focus location. A clear texture of the scene (object) is composed by collecting the brightness values from the respective focused 128 (or 256) frames. Reconstruction of the 3-D sketch is tested by mapping the texture on the depth map. The usefulness of a polarized filter is also demonstrated to recover an accurate depth map in the presence of specular reflection