An analysis of the effects of distributed light sources for surface gradient recovery using reflectance maps and computer simulation

摘要

Recent work has identified photometric stereo as a means for the recovery of surface data using idealised point source or collimated lighting. The approach has the potential to undertake new kinds of tasks that were impossible using existing techniques. However, in terms of practical application within industrial inspection, it is often difficult to realise an ideal form of illumination. This paper presents an investigation into the effects of employing 'every day' light sources for surface information recovery using the photometric stereo method. Important variables are identified in terms of light source distribution, position and divergence. Computer simulation and reflectance maps help demonstrate these disparities and their influence on the reliability of the recovered surface information. Hence, a mechanism is provided for determining the most suitable form of lighting arrangement, for a particular system resolution, in the proposal of such systems.