Preliminary Study on Camera-Laser Calibration for Underwater Laser Scanning

Abstract

Most of the reconstruction results of underwater cases can be made by range data from acoustic equipment such as single or multi-beam echo sounder. Underwater acoustics are able to reach up to a depth of a few kilometers; hence, the acoustic equipment is effective for global three-dimensional reconstruction. To reconstruct more detail and recognize some underwater objects, acoustic equipment is not the ideal solution owing to the uncertainty of its acoustic performance. In this paper, we present a preliminary experimental result of camera-laser calibration and reconstruction for underwater laser scanning. To obtain precise three-dimensional information, camera-laser calibration and image processing is needed.First, the camera image coordinates and laser coordinates must be calibrated to determine rotation and translation. For calibration, we adopt a triangulation-based shape acquisition method proposed by Josep Forest et al [1]. Next, we design a simple image processing sequence to detect a projected laser line in the image. From the calibration and laser-line-in-pixel data, we can calculate the three-dimensional information of underwater objects or the seabed. In the experiment section, we report reconstruction results of developed camera-laser system.