Application of structured light coding measurement technology in Mars high-resolution camera

Structured light coding measurement technology is typically adopted in the measurement of the three-dimensional topographies of components of the Mars high-resolution camera. Conventional structured light coding measurement technology employs the method of sine phase shift symmetry in combination with the Gray code, which easily produces periodic dislocation errors, significantly affecting the measurement accuracy. To eliminate the periodic dislocation error in principle, in this study, we propose an asymmetric structured light coding measurement technology. First, the concept of region encoding for four-step sinusoidal phase-shifting is proposed. Then, the sinusoidal phase-shifting is combined with cyclic code asymmetrically. Given that the cyclic code and region code vary with time, the cyclic dislocation error is reduced from one cycle to one pixel owing to the dual constraint of the cyclic code and region code. The simulation measurement results of the 3ds Max and the physical measurement results indicate that in comparison with the conventional measurement technology, the maximum measurement error of the asymmetric structured light coding measurement technology is relatively reduced by an order of magnitude, and the mean square measurement error is relatively reduced by 70%. The asymmetric structured light coding measurement technology effectively eliminates periodic misalignment errors and substantially improves the three-dimensional measurement accuracy. © 2021 Science Press. All right reserved.