Design and Implementation of a Passive Stereo-Infrared Imaging System for the Surface Reconstruction of Water Waves

To quantify air-sea exchange processes, an understanding of how they are influenced by water waves is necessary. This work presents a passive, infrared stereo-imaging system for the reconstruction of a wavy water surface. The system does not require a sub-merged light source, so it is suitable for field operation. The structure of the thesis is as follows. Previous work on water wave imaging is reviewed and the major problems with stereo-based reconstruction of water surfaces are identified: transparency, lack of texture and specular reflections. It is shown that many of these problems can be avoided by imaging at infrared wavelengths. Following a review of infrared radiometry, the key ingredients of surface reconstruction using the stereo principle are explained, including camera calibration, epipolar geometry and disparity estimation. A description of the stereo infrared camera system used in this work is given. An experimental validation of the system was performed at the Heidelberg wind-wave channel. Several stereo infrared image sequences of water waves recorded at this facility are used to demonstrate that a dense surface reconstruction of water waves is possible using this system. The accuracy of the reconstruction is experimentally assessed using a flat water surface as a reference plane.