ENVISAT ASAR Wide Swath and SPOT‐VEGETATION Image Fusion for Wetland Mapping: Evaluation of Different Wavelet‐based Methods

Abstract

Three wavelet‐based fusion methods (ARSIS, PSIMA and à trous method) are applied to combine ENVISAT ASAR Wide Swath and SPOT‐VEGETATION images. The objectives of the data fusion are feature enhancement and improvement of classification accuracy of a tropical wetland located in the Chad basin, Africa. The fusion results are compared to those obtained by the intensity hue saturation (IHS) method and the principal component (PC) method. Several quantitative tests and a visual inspection are performed to evaluate the different methods. The fused images are classified by means of a maximum likelihood classifier and the classification accuracies are calculated.

The results show that the fusion methods based on the wavelet transform perform better then the IHS and PC method for both objectives. From all methods, the ARSIS and the à trous method preserve best the spectral contents of the SPOT‐VEGETATION image. However, the à trous method outperforms the ARSIS method in terms of spatial information preservation. When the PSIMA method is used, artefacts are minimized. The highest classification accuracies are obtained with the PSIMA and à trous methods.