Independent Component Analysis (ICA) performance to bathymetric estimation using high resolution satellite data in an estuarine environment

Abstract

The use of satellite remote sensing data is a valid alternative to the classical survey bathymetric methods for bathymetric estimation in shallow waters. Multispectral satellite data has been used to produce bathymetric maps by considering the pixel reflectance as a depth indicator. Teodoro et al., (2010) already proposes a model for the estimation of depth based on Principal Component Analysis (PCA) of an IKONOS-2 image, for the Douro River estuary (Porto, Portugal). In this work, alternative univariate and bivariate models are proposed for the same IKONOS-2 image based on PCA and Independent Component Analysis (ICA). The PCA is the standard method for separating mixed signals. Such analysis provides signals that are linearly uncorrelated. Although the separated signals are uncorrelated they could still be depended, i.e., nonlinear correlation remains. The ICA was developed to investigate such data. Fast ICA algorithm was used in Matlab®. The results obtained were compared with the bathymetric estimation trough PCA. Best univariate ICA based model allowed to estimate depth with a mean error of 0.00m [with 1.15 of standard deviation], outperforming the best PCA based univariate model results of 0.39[1.34], even with the first PCA component explains 80% of data variance. With bivariate models is possible to reduce the standard deviation of the error to 1.01m.