DISCRIMINATION DES ZONES HUMIDES EN FORET MALGACHE, PROPOSITION D'UNE METHODOLOGIE MULTIRESOLUTION ET MULTISOURCE UTILISANT ORFEO TOOLBOX.

The marshes, wich are potentially suitable for conversion into paddy fields, offer future possibilities for clearness in tropical forest area. A processing chain for multirésolution and multisource satellite images, using Orfeo ToolBox, is put to test in order to discriminate wetlands, water, marshes and paddy fields. This methodology combines radiometric indices extracted from images containing more spectral bands with textural indices from high spatial resolution images. Thus, the spectral information of an image from Landsat 7 ETM+ satellite at 30 m resolution, is used for identifying wetlands and for drawing up their regional mapping. The textural information of 10 m and 2.5 m images from SPOT 5 satellite is used to discriminate wetland types and to map them at the local scale. By combining data from both satellites, the areas of water, wetland and paddy fields were evaluated, with Kappa coefficient (0.8), in two districts of the forested corridor of Fianarantsoa (Madagascar). [ABSTRACT FROM AUTHOR]