Image Based Method to Estimate Regular Wave Parameters

Image based methods, particularly those applying stereoscopic approaches, have difficulty in measuring waves produced in laboratory facilities, mainly because, in such conditions, the water surface is smooth, translucent and highly specular. The present study introduces a method to estimate regular wave parameters (particularly the amplitude) that is capable of dealing with such characteristics of the surface. The method is based on image intensity and its relationship with the surface normal. Although the concepts behind the method are well known since the 1960 decade, we present a novel framework of algorithms and experimental setup which produces promising results even using cheap cameras and under regular laboratory illumination conditions. The specific set of results reported herein was obtained by a single camera; however, multiple cameras can be used both to improve the quality of calibration parameters and to reduce the overall estimation errors. To conclude, we present conjectures regarding the expansion of the method to measure irregular waves and to deal with more unrestricted illumination conditions.