In this paper we describe an efficient image-based approach to compute volume 
models from silhouette images in a low cost measuring environment. First, the 
contours of a real object must be extracted from a sequence of images. In a 
second step, a bounding pyramid is constructed using the projection center and 
the silhouette. The intersection of all bounding pyramids defines an approximate 
geometric representation for the object called visual hull. Silhouette based 
constructions have the principal inability to detect the object concavities. We 
present some new results to minimize the modeling error on critical areas using 
a block matching approach.