Three 1-bit speckle-embedded pulse-width modulation patterns for robust absolute 3D measurement

Abstract

In 3D shape measurement techniques using structured light, 1-bit pulse-width modulation (PWM) patterns and 1-bit speckle patterns can be projected at high speed. However, when combining PWM and speckle patterns to integrate their advantages, the decoupling problem is insurmountable. In this work, a novel 1-bit speckle-embedded pulse-width-modulation (SP-PWM) patterns was proposed to achieve absolute 3D shape measurement using only three binary patterns. Our method consists of three main steps: First, a sinusoidal pattern reconstruction network (SPRNet) was proposed to eliminate the high-order harmonics and speckle patterns in the SP-PWM patterns and obtain high-quality sinusoidal patterns. Second, a multi-temporal spatial correlation matching algorithm (MTSCMA) was proposed to obtain a coarse disparity map from the three SP-PWM patterns. Third, the high-accuracy wrapped phase map is used as an additional constraint for refining the coarse disparity map to obtain the final high-accuracy disparity map for absolute 3D measurement without phase unwrapping. Our method combines the advantages of fringe projection profilometry techniques for high-precision wrapped phase retrieval and speckle correlation matching algorithms for robust and unambiguous disparity map calculation. The experimental results demonstrated that our method could realize high-precision absolute 3D shape measurement with an accuracy of 0.057mm using only three 1-bit SP-PWM patterns. Furthermore, different simulation noises were used to demonstrate the robustness of the proposed method.