Nearshore Wave Measurement Using Single-Video Images of Buoy Motions

This paper presents a wave measurement technique based on single-video monitoring of moored buoys. A simple photogrammetry is proposed, with a constraint that the distance from video camera to buoy should be predetermined. The distance is approximated to a constant under the condition that it is much greater than the range of the buoy motion. Image coordinates of a buoy are mapped onto a spherical surface without significant errors in vertical ground coordinates. Wave characteristics are comparable to those from a bottom pressure gauge, indicating that the video technique has the potential to remotely measure waves in coastal environments. We anticipate our finding to be a starting point for an economic instrument of wave measurement through development of an automated image processing technique.