Rapizo, H.; d'Avila, V.; Violante-Carvalho, N.; Pinho, U.; Parente C.E., and Nascimento, F., 2016. Simple techniques for retrieval of wind wave periods and directions from optical images sequences in wave tanks.

Optical techniques are potentially suitable for overcoming some of the limitations faced by single-point sensors, like buoys, in retrieving spatial properties of wind-generated waves. However, most of the approaches that have been addressed in the literature employ complex configurations that use a coupling system between cameras, making its implementation difficult. This article describes simple techniques for measuring the period and direction of multimodal, regular waves, employing a single, commonly available camera. Furthermore, there is no special requirement for light conditions, making its implementation feasible, in both indoor and outdoor environments. Several tests were conducted in a multidirectional tank, varying the steepness and direction of the waves. The optical measurements were in good agreement, especially for waves from moderate to greater steepness. The techniques described here could be employed as a preliminary step before tackling more-complex configurations, for instance, as a priori information on the main wave modes.