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Remote Sens. 2013, 5(4), 1856-1874; doi:10.3390/rs5041856
Article

Signal Classification of Submerged Aquatic Vegetation Based on the Hemispherical–Conical Reflectance Factor Spectrum Shape in the Yellow and Red Regions

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Received: 20 February 2013; in revised form: 25 March 2013 / Accepted: 25 March 2013 / Published: 15 April 2013
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Abstract: The water column overlying the submerged aquatic vegetation (SAV) canopy presents difficulties when using remote sensing images for mapping such vegetation. Inherent and apparent water optical properties and its optically active components, which are commonly present in natural waters, in addition to the water column height over the canopy, and plant characteristics are some of the factors that affect the signal from SAV mainly due to its strong energy absorption in the near-infrared. By considering these interferences, a hypothesis was developed that the vegetation signal is better conserved and less absorbed by the water column in certain intervals of the visible region of the spectrum; as a consequence, it is possible to distinguish the SAV signal. To distinguish the signal from SAV, two types of classification approaches were selected. Both of these methods consider the hemispherical–conical reflectance factor (HCRF) spectrum shape, although one type was supervised and the other one was not. The first method adopts cluster analysis and uses the parameters of the band (absorption, asymmetry, height and width) obtained by continuum removal as the input of the classification. The spectral angle mapper (SAM) was adopted as the supervised classification approach. Both approaches tested different wavelength intervals in the visible and near-infrared spectra. It was demonstrated that the 585 to 685-nm interval, corresponding to the green, yellow and red wavelength bands, offered the best results in both classification approaches. However, SAM classification showed better results relative to cluster analysis and correctly separated all spectral curves with or without SAV. Based on this research, it can be concluded that it is possible to discriminate areas with and without SAV using remote sensing.
Keywords: hyperspectral; submerged aquatic vegetation; cluster analysis; spectral angle mapper; continuum removal hyperspectral; submerged aquatic vegetation; cluster analysis; spectral angle mapper; continuum removal
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Watanabe, F.S.Y.; Imai, N.N.; Alcântara, E.H.; da Silva Rotta, L.H.; Utsumi, A.G. Signal Classification of Submerged Aquatic Vegetation Based on the Hemispherical–Conical Reflectance Factor Spectrum Shape in the Yellow and Red Regions. Remote Sens. 2013, 5, 1856-1874.

AMA Style

Watanabe FSY, Imai NN, Alcântara EH, da Silva Rotta LH, Utsumi AG. Signal Classification of Submerged Aquatic Vegetation Based on the Hemispherical–Conical Reflectance Factor Spectrum Shape in the Yellow and Red Regions. Remote Sensing. 2013; 5(4):1856-1874.

Chicago/Turabian Style

Watanabe, Fernanda S.Y.; Imai, Nilton N.; Alcântara, Enner H.; da Silva Rotta, Luiz H.; Utsumi, Alex G. 2013. "Signal Classification of Submerged Aquatic Vegetation Based on the Hemispherical–Conical Reflectance Factor Spectrum Shape in the Yellow and Red Regions." Remote Sens. 5, no. 4: 1856-1874.


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