Accurate and Practical 3D Measurement for Translucent Objects by Dashed Lines and Complementary Gray Code Projection

We propose a practical 3D method for measuring translucent objects with high accuracy. We improve the accuracy of the measurement by a high-frequency dashed line projection to a target object, which eliminates the influence of subsurface scattering while maintaining higher image contrast. For efficient measurement, multiple dashed lines are projected at the same time and we identify them without error by a proposed complementary Gray code, thus reducing the number of projections to less than 1/10 of that by conventional light sheet scanning. With regard to performance, we show that the frequency of the dashed line largely determines the accuracy and that there is a trade off between depth offset as a systematic error and random error. We validate the proposed method by measuring both canonical translucent samples with various translucencies and actual engineering parts.