Temporal Matrices Mapping-Based Calibration Method for Event-Driven Structured Light Systems

Abstract

Strong ambient illumination severely degrades the performance of conventional structured light 3D imaging systems due to the limited sensor bandwidth and light source power. In contrast, event-driven structured light techniques fully take advantage of laser-galvanometer scanning and event-detection property, which can achieve robust 3D reconstruction under such challenging scenarios. However, the low measurement accuracy of such systems severely hinders their extensive applications, as no accurate calibration method has yet been developed for them. In this work, we propose a novel Temporal Matrices Mapping (TMM) based calibration algorithm for event-driven structured light systems. The crucial step of our method is establishing the pixel correspondences between the galvanometer and event camera image planes with two temporal matrices. Specifically, we 1) scan a front-parallel plane vertically and horizontally to attain two temporal matrices; 2) estimate the coordinates of feature points on the galvanometer image plane through the temporal matrices and corresponding scanning speeds. In order to make the most of our calibration method, we present a disparity correction approach for depth calculation. We developed a prototype system to validate the proposed algorithms. Experimental results demonstrate that the calibration algorithm can reach sub-pixel precision, and the system's measurement error can achieve 0.2%, which outperforms the typical 1.0% of the state-of-the-art.