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Remote Sensing of Nearshore Currents using Coastal Optical Imagery
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  • Journal title : Ocean and Polar Research
  • Volume 37, Issue 1,  2015, pp.11-22
  • Publisher : Korea Institute of Ocean Science & Technology
  • DOI : 10.4217/OPR.2015.37.1.011
 Title & Authors
Remote Sensing of Nearshore Currents using Coastal Optical Imagery
Yoo, Jeseon; Kim, Sun-Sin;
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In-situ measurements are labor-intensive, time-consuming, and limited in their ability to observe currents with spatial variations in the surf zone. This paper proposes an optical image-based method of measurement of currents in the surf zone. This method measures nearshore currents by tracking in time wave breaking-induced foam patches from sequential images. Foam patches in images tend to be arrayed with irregular pixel intensity values, which are likely to remain consistent for a short period of time. This irregular intensity feature of a foam patch is characterized and represented as a keypoint using an image-based object recognition method, i.e., Scale Invariant Feature Transform (SIFT). The keypoints identified by the SIFT method are traced from time sequential images to produce instantaneous velocity fields. In order to remove erroneous velocities, the instantaneous velocity fields are filtered by binding them within upper and lower limits, and averaging the velocity data in time and space with a certain interval. The measurements that are obtained by this method are comparable to the results estimated by an existing image-based method of observing currents, named the Optical Current Meter (OCM).
digital optical imagery;surf zone;nearshore currents;remote sensing;wave-induced foam;
 Cited by
Chickadel CC, Holman RA, Freilich MH (2003) An optical technique for the measurement of longshore currents. J Geophys Res 108(C11):3364. doi: 10.1029/2003JC001774 crossref(new window)

Guza R, Thornton E, Christensen Jr N (1986) Observations of steady longshore currents in the surf zone. J Phys Oceanogr 16(11):1959-1969 crossref(new window)

Haas KA, Svendsen IA (2002) Laboratory measurements of the vertical structure of rip currents. J Geophys Res 107(C5). doi: 10.1029/2001JC000911 crossref(new window)

Holland KT, Holman RA (1993) The statistical distribution of swash maxima on natural beaches. J Geophys Res 98(C6):10271-10278. doi: 10.1029/93jc00035 crossref(new window)

Holland KT, Holman RA, Lippmann TC, Stanley J, Plant N (1997) Practical use of video imagery in nearshore oceanographic field studies. Ieee J Ocean Eng 22(1):81-92. doi: 10.1109/48.557542 crossref(new window)

Holland KT, Puleo JA, Kooney TN (2001) Quantification of swash flows using video-based particle image velocimetry. Coast Eng 44(2):65-77. doi: 10.1016/S0378-3839(01)00022-9 crossref(new window)

Inman DL, Bagnold R (1963) Littoral processes. The sea 3:529-553

Komar PD (1998) Beach processes and sedimentation. Prentice Hall, Upper Saddle River, NJ, 546 p

Longuet-Higgins MS (1970) Longshore currents generated by obliquely incident sea waves: 1. J Geophys Res 75(33):6778-6789 crossref(new window)

Lowe D (2004) Distinctive image features from scaleinvariant keypoints. Int J Comput Vision 60(2):91-110. doi: 10.1023/B:VISI.0000029664.99615.94 crossref(new window)

Ruessink B, Miles J, Feddersen F, Guza R, Elgar S (2001) Modeling the alongshore current on barred beaches. J Geophys Res 106(C10):22451-22463 crossref(new window)

Stockdon HF, Holman RA (2000) Estimation of wave phase speed and nearshore bathymetry from video imagery. J Geophys Res 105(C9):22015-22033. doi: 10.1029/1999jc000124 crossref(new window)

Yoon SB, Park WK, Choi J (2014) Observation of rip current velocity at an accidental event by using video image analysis. J Coastal Res SI 72:16-21 crossref(new window)