Improved topography reconstruction of volume scattering objects using structured light.

The use of structured light projection enables the reconstruction of three-dimensional topography of surface reflecting objects. However, if the investigated object exhibits volume scattering, the obtained topography is erroneously caused by light undergoing volume scattering inside the object. In this theoretical study, we investigate these errors using Monte Carlo simulations. Additionally, a method is proposed to correct the errors by quantifying the light propagation in the scattering object based on the radiative transfer equation. Reconstructed surfaces with a small spatial variation of topography can be quickly corrected using a local correction method that depends only on the directions of the incident and detected light relative to the surface. For surfaces that show a large spatial variation of the surface geometry, another approach is introduced by simulating the light propagation in the whole scanned three-dimensional object using graphics processing unit (GPU)-accelerated Monte Carlo simulations. A cylindrical object and an incisor tooth are, exemplarily, investigated. The results show a major improvement in the reconstructed topography due to the correction with the proposed methods.