Search-free stereo-PMD: iterative reconstruction based on specular region consistency

Stereoscopic phase measuring deflectometry (stereo-PMD) is widely used in the measurement of specular surfaces due to its superiority in solving the height-slope ambiguity and model-free nature compared with mono-PMD. Reconstruction in stereo-PMD starts with the search for spatial points based on normal consistency criterion to specify the position of slope sampling plane (SSP), but the results are not necessarily unique. In this work, for stereo-PMD, an iterative reconstruction method is proposed to eliminate the point cloud search and positional consideration of SSP. Instead, the constraint of specular regions consistency is used to supersede the normal consistency to dynamically optimize the position of SSP. Experimental results demonstrate the improvement over 80% in low-order accuracy and 33% in noise robustness.