High dynamic range 3D laser scanning with the single-shot raw image of a color camera

Abstract

As a typical technique of optical three-dimensional (3D) shape measurement, laser scanning can provide good measurement accuracy by using simple and low-cost optical configuration. The performance of 3D laser scanning greatly depends on the center detection of the laser stripe. In general, laser stripe detection algorithm expects the intensity of the laser stripe remaining moderate and stable. To deal with the negative impact of dramatic change in the intensity of the laser stripe, a high dynamic range (HDR) laser scanning technique with concise algorithm and simple hardware configuration is proposed in this paper. The Bayer filter in the sensor chip of a color camera is exploited to provide different intensity responses to the laser. Then the sub-images of the laser stripe, which correspond to different color channels and have different intensity levels, can be decomposed from the raw image captured by the color camera. A dedicated algorithm is proposed to achieve HDR laser stripe detection, which collects coordinates with the best quality from different sub-images. Finally, 3D surface of improved quality can be reconstructed with the detected laser stripe. The proposed HDR laser scanning technique can be achieved from single-shot raw image by trading pixel resolution for time efficiency. The validity of the proposed method is demonstrated in comparative experiments.