Measurement of water surface elevation using Moire techniques

Wave interaction between the components of oil rigs composed of large diameter members is of considerable practical importance. An optical method is described to identify the modification of the incident wave within the well of large diameter blocked structures arising from interaction effects. The paper describes Moire techniques to obtain immediate three dimensional records of the so-called upwelling phenomenon. This optical method combined with image processing techniques can be strobed so that the behaviour of the sea can be described as a series of images of wave elevation to be obtained with a contour interval of some millimeters. Results are presented to demonstrate the efficiency of the method. This method is developed for application to problems involving floating structures design such as tension leg platforms, etc.