Microlens Array-Based Spatial Angle Encoding for High-Precision Visual Pose Measurement

To improve the precision and robustness of angle measurement by existing visual marker methods, a high-precision visual pose measurement approach that combines microlens arrays and random micrographics arrays for encoding is proposed. First, in the calibration stage, dense and high-precision encoding is carried out by dynamic imaging modes of random micrographics arrays under microlens arrays, and a high-precision coordinate datum of spatial angles is constructed by the Hamming code. Then, in the measurement stage, observation angle encoding is completed on the basis of observed display images, the weighted fusion of which with the nearest angle datum is applied to obtain the precise angles of measuring positions. In this way, the triaxial angle measurement and pose estimation with high precision can be achieved. At the same time, extensive experiments are performed to verify the validity of the proposed method. The results reveal that the angle measurement precision is higher than 0.08°, and compared with the results of previous work, the average angle measurement error is reduced by 97% without sacrificing the displacement measurement precision. In addition, the robustness of the proposed algorithm ensures high-precision pose measurement under natural illumination. Finally, by sufficient quantitative comparison, the effects of factors on angle measurement precision, such as threshold segmentation and angle encoding parameters, are comprehensively analyzed. © 2022, Chinese Lasers Press. All right reserved.