Preliminary Study for Detecting of Ocean Wave Parameters using CCD Images

Recently, researchers have been developed the technology for monitoring in the coastal zone using a remote sensing to manage and analyze the beach processes. Many of these approaches translate the data model of beach process as a queue of avoidance of emergency situation in a beach, such as coastal erosion risk management. However, sensor based approaches have a crucial limitation, which needs a high cost and has a worry about malfunction. To overcome these problems, a video-based beach monitoring system, which can analyze the wave periods and height, was introduced in this study. A CCD camera is one of best choice to monitor a movement of arbitrary behaviour, because it has a several benefits, especially it does not need high cost equipment, then other sensor-based approach relatively, and has a strong resistance to the external environment except for light. The ocean wave change in CCD image clips, when it reaches the shallow water contains an extreme discontinuity, especially a change in the shape of marine space. So our system extracted the contour of video patches in an each frame and then compared their shape using the seven Hu-moments. The Hu-moments constitute a measure of the similarity of the matrix form between video frames. The radial symmetric kernel was applied to the similarity matrix, which is able to express the wave period and height, respectively. The wave period, which was detected by the Hu-moments algorithm at the Gyoam Beach in Republic of Korea were compared with the wave information collected by an under-water pressure type wave meter. The results of this study confirm that the CCD camera with Hu-moments algorithm is applicable to detect wave period with a slight bias and, consequently, to clarify the complex characteristics of wave distribution and its temporal change.