Ranging of Turbulent Water Surfaces Using a Laser Triangulation Principle in a Laboratory Environment

Abstract

A measuring system based on laser triangulation for ranging a turbulent water surface in a laboratory environment is presented in this paper. The system is composed of a light detection and ranging (LIDAR) device, serving as a light source, and a high-speed camera. Single-point illumination was chosen to facilitate the introduction of the epipolar line in the image-processing step and thus improve the distinction between primary and other reflections, which increase the uncertainty of the measurement and introduce noise. The system was used to measure the water surface in an open channel confluence, which is composed of main and tributary channels, which join at a 90° angle. The surface was measured for 2.01 s, resulting in 54,682 points measured in 543 profiles. The influence of image process parameters (height and width of filtering kernel and width of area surrounding the epipolar line) on smooth and rough water surface was studied. The results show that the parameters’ influence is at least an order of magnitude smaller than the amplitude of water surface fluctuation.