Ocean remotely sensed image analysis using two-dimensional continuous wavelet transforms |
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| Authors: | Li-Chung Wu Dong-Jiing Doong Chia Chuen Kao |
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| Affiliation: | 1. Department of Hydraulic and Ocean Engineering , National Cheng Kung University , Tainan , Taiwan;2. Department of Marine Environmental Informatics , National Taiwan Ocean University , Keelung , Taiwan |
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| Abstract: | Ocean remote sensing is a useful way to obtain ocean wave information. Due to possible inhomogeneities from remotely sensed images, the current work proposes issues concerning ocean wave image analysis using the two-dimensional continuous wavelet transforms (2-D CWTs) to calculate local wave image spectra from inhomogeneous images. To optimize the algorithm of the 2-D CWT for wave image analysis, this work explores ideal parameter values for the wavelet function. The current study also analyses the limits of spatial image resolution and wave image size. After implementing the 2-D CWT on satellite and X-band radar images, this study presents local image spectra and ocean wave information from all the ocean images. These local image spectra reveal the phenomenon of wave refraction and wave nonlinearity nearshore. Compared to real wave spectra, the wavelet spectra present accurate results to describe local wave features in the spatial frequency domain. |
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