Surface Reconstruction based on Visual Information

Computer Vision Group, FR 3-11 Computer Science Department, Berlin Technical University, D-10587 Berlin, Germany http://www.cs.tu-berlin.de/~cvworld {klette,koschan,karsten,vr}@cs.tu-berlin.de Abstract The computation of surface data based on visual information is an important sub-component in the computer-graphical surface reconstruction of solids and in the control of 3-D environments. Different methodologies can be used for that as, e.g., static stereo, shape from motion, shape from shading, photometric stereo, or structured lightening. There exist different basic approaches in literature often based on simplifying assumptions. However, it is well known that such assumptions may not be true if surface reconstruction is applied under practical circumstances. In this paper, several problems are mentioned which are related to practical applications of surface reconstruction approaches following the methodologies of static stereo, shape from motion, and photometric stereo. We present specific solutions to cope with these problems, or the solution state what was reachable in our work. Some problems are ill-posed and limitations of approaches have to be accepted. As a second contribution of this paper, we discuss the evaluation problem of surface reconstruction algorithms. It is important to answer such questions as 1) For what kind of surfaces and 3-D objects an algorithm behaves either well or bad? 2) How accurate are the reconstruction results of an algorithm under specified circumstances? What measure can be used to evaluate reconstruction accuracy? 3) How to compare reconstruction results following different methodologies? 4) What algorithm can be suggested for a specific application project? and so on. So far we present some proposals and first quantitative or qualitative results for answering such questions. In our opinion a methodology for evaluating surface reconstruction algorithms is still at its beginning. However a critical evaluation of potential methods in project applications is helpful in selecting the appropriate algorithm.