A Study on Optimal Light Source Configuration in Photometric Stereo

Abstract

A study on optimal light source configuration in photometric stereois carried out in this thesis. Under Gaussian camera noise, the captured image intensity is corrupted by noise which makes error in reconstructed surface normal. Optimal light source configuration has been found for grayness photometric stereo to minimize that error. For the first time in this document, the optimal light source configuration is researched for color photometric stereo in which assumptions proposed for grayness photometric stereo are no longer suitable for color photometric stereo. Different assumptions are needed making the optimal configuration formulation become much more complicated in color photometric stereo.For three light source, not overlapped spectra case, orthogonal illumination directions are proved as optimal configurations regardless of the difference in camera noises

however, for the overlapped spectra, orthogonal directions are not optimal configuration any more. In regard to not overlapped-spectra morethan three light sources, numerical calculation points out that the n-dimensional orthonormal vectors constituted from x, y, z co-ordinates of n light source directions, which are optimal configuration in grayness counterpart, are no longer optimal configuration. Furthermore, for one special case in which light sources are equally separated on a circle of uniform slant, the optimal slant angles is found as θ=54.73560 for any value of number of light sources and the noise variance parameters.