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Communication Dans Un Congrès Année : 2008

Performances comparison of bathymetry on rivers from various visible high resolution images

Comparaison de performances de mesure de bathymétrie par images haute résolution

Résumé

Bathymetry data on river are crucial elements for hydro-morphology and hydroecology but difficult and costly to measure. In case of clear water river, the use of remote-sensing images might suit to produce realistic depth maps of shallow water areas [Carboneau et al., 2004]. In this study, three sites have been studied on the graved-bed river Durance (France). On these test sites, a high quantity of ground data were available. Three Very High Spatial Resolution images shoted at same time as ground data were compared: two aerial images acquired by plane (Bd-Ortho© IGN) or ULM (Avion Jaune Company) in natural colours (Red, Green, Blue) with 0.5 m resolution and one provided by the Quickbird satellite in multispectral (R, G, B, Infrared) with 2.4 m and 0.7 m resolutions. For each shot, a model of the relation between colors and depth has been fitted using linear regression. In the case of simple linear regressions, a determination coefficient of 0.4 was found in the best case and most models are very poorly relevant. On the contrary, results using a stepwise multi-linear regression according Lysenga equation are more significant with a maximum of determination coefficient up to 0.71. In most cases, only two spectral bands were identified as significant to establish a fairly good model for each shot. According to the error maps, a link is supposed on the one hand between high depths and under-assessment by the method and, on the other hand, between algae excess and over-assessment.Image pre-treatment and resolution appear to be two important parameters influencing the model fitting. Tests of model inter-crossing between each shot and images were realised in order to assess their suitability and generalization ability. These first results shows a difficult direct generalisation of regression models and highlights, for aerial images, the necessity of the images normalization using some radiometric pre-treatments. Thanks to CNES-ORFEO project (France) for providing Quick-bird images.

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Dates et versions

hal-02591397 , version 1 (15-05-2020)

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J. Damis, C. Delenne, Jean-Stéphane Bailly, C. Puech. Performances comparison of bathymetry on rivers from various visible high resolution images. EGU, Apr 2008, Vienne, Austria. pp.2. ⟨hal-02591397⟩
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