3D Measurement Based on Row-wise LT Matrix Estimation

3D Measurement is an essential element of robotics for industrial usage. Many methods have been proposed so far, but some objects with specular reflections or subsurface scatterings are difficult to measure the shape accurately. We have developed a new method by using projector-camera Light Transport (LT) Matrix. LT Matrix is often used in computer graphics to make relighting images, light path understanding, and 3D measurement. It is useful for describing light paths on projector-camera system because it includes all light reflection information. However, it takes a long time to measure LT Matrix accurately. This paper first proposes how to obtain 3D shape from LT Matrix. Then we propose fast LT Matrix estimation method by using its sparseness. Our method can estimate accurate LT Matrix to obtain 3D shape in short time. Finally, we compare our results and previous 3D measurement methods, and we conclude our methods performs much better than other methods for metallic or transparent objects.