Abstract
Abstract. This paper will describe a novel approach for the calibration of an underwater laser triangulation system. Underwater triangulation systems, consisting of a line laser and a camera can be used to determine the geometry of submerged objects or the topography of a water body bottom. Placing camera and laser line projector inside a waterproof housing leads to refraction effects at the air-glass-water interfaces, both of the laser light-sheet and image rays. This implies a deformed laser plane in the water and a curved line on the object surface. The proposed approach strictly models the geometry between camera, laser and housing. First experiments show, that the calibration method can be applied for water depth measurements with accuracies of 0.2–0.3 mm at depths in the order of 100 mm.
Highlights
This paper will describe a novel approach for the calibration of an underwater laser triangulation system
A triangulation system consisting of a line laser and a camera is used for underwater depth measurement
For validation of the calibration procedure, a triangulation system, consisting of a green laser and an industrial camera has been placed in a glass housing
Summary
This paper will describe a novel approach for the calibration of an underwater laser triangulation system. Placing camera and laser line projector inside a waterproof housing leads to refraction effects at the air-glass-water interfaces, both of the laser light-sheet and image rays. This implies a deformed laser plane in the water and a curved line on the object surface. When laser triangulation is used in underwater environments, there are two main adaptions necessary: First, because of the increasing opaqueness of water for higher wavelengths (Hale and Querry, 1973), a green or blue laser is usually chosen Both the laser plane and the image rays are refracted at the air-housing and housing-water interfaces. The approach proposed in this paper considers rotation of the laser around all axes
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