Recovering shape in the presence of interreflections

An algorithm for recovering the shape and reflectance of Lambertian surfaces in the presence of interreflections is presented. The surfaces may be of arbitrary but continuous shape, and with possibly varying and unknown reflectance. The actual shape and reflectance are recovered from the pseudoshape and pseudoreflectance estimated by a local shape-from-intensity method (e.g., photometric stereo). Thus, the algorithm enhances the performance and the utility of existing shape-from-intensity methods. From the results reported, two observations can be made that are pertinent to machine vision: interreflections can cause vision algorithms to produce unacceptably erroneous results and hence should not be ignored; and at least some interreflection problems are tractable and solvable.>