Optical tomography based on shortest-path model for diffuse surface object

We tackle an optical measurement of the internal structure of a diffuse surface object—we define as an object that has a diffuse surface and its interior is transparent, like grapes or hollow plastic bottles. Our approach is based on optical tomography that reconstructs the interior from observations of absorption of light rays from various views, under the projection of the light. The difficulty lies in the fact that a light ray that enters changes its direction at the interaction of the surface, unlike X-ray that travels straight through the object. We introduce a model of light path in the object called shortest-path model. We acquire the absorption of light rays through the object by the measurement upon the assumption of the model. Since this measurement acquires insufficient observation to reconstruct the interior by conventional reconstruction algorithms, we also introduce a reconstruction method based on a numerical optimization that a physical requirement of the absorption is taken into account. Our method is confirmed successful to measure the interior in a real-world experiment.