SHAND, T.D.; BAILEY, D.G., and SHAND, R.D., 2012. Automated detection of breaking wave height using an optical technique.
Obtaining accurate information of nearshore wave characteristics including the position and height of individual breaking waves is essential to understanding the drivers of coastal processes, for engineering design and hazard prediction. Demand for such information in real time for recreational planning and hazard assessment is also high. Remote optical techniques would offer considerable economic and spatial coverage advantages over conventional in situ instrumentation. However, optical methods for obtaining wave height information have been slow to develop and those available remain computationally expensive and require “favourable” environmental conditions. This paper presents a relatively simple yet robust approach to detecting and quantifying breaking wave position and height across a wide surf zone using a twin video camera configuration coupled with an image time-stack analysis approach. A numerical algorithm, HbSTACK, is developed and successfully tested under the environmental conditions experienced during field trials. Errors and uncertainties may arise in both the photogrammetric transformation from pixels to real-world coordinates and in the detection of wave crest and trough positions. These errors have been assessed using both field verification of the transformation model and manually detected crest and trough locations by experienced practitioners. Errors in output wave heights were thus estimated to be less than 7%.