Variation of Incident Wave Angle in the Surf Zone Observed from Digital Videos

해안 비디오로부터 관측된 쇄파지역에서 입사각의 변화

  • Yoo, Je-Seon (Climate Change & Coastal Disaster Research Department, KORDI) ;
  • Shin, Dong-Min (Department of Civil and Environmental Engineering, Hanyang University) ;
  • Cho, Yong-Sik (Department of Civil and Environmental Engineering, Hanyang University)
  • 유제선 (한국해양연구원 기후연안재해연구부) ;
  • 신동민 (한양대학교 건설환경공학과) ;
  • 조용식 (한양대학교 건설환경공학과)
  • Published : 2009.04.30

Abstract

Incident wave angles are conventionally estimated by the directional spectrum analysis of wave data collected from in-situ sensors. The in-situ measurements are limited in monitoring incident wave angles in the wide surf zone, since the techniques are typically expensive, labor-intensive, and point-measuring. In this study, estimation of incident wave angles using wave crest features captured in digital video imagery is proposed to observe incident wave directions over the surf zone. Line signatures of wave crests having high image pixel intensities are extracted by moving an interrogation window to identify high intensity pixels in sequential video images. Wave angles are computed by taking the first derivative of the extracted crest signatures, i.e. local slope of the crest signatures in the two-dimensional physical plane. Compared to the wave angle estimates obtained by the directional spectrum analysis, video-based wave angle estimates show good agreements in general.

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