De la synergie des images satellitaires SPOT/ERS au travers de deux exemples de fusion

Abstract : Nowadays, imaging sensors aboard satellites use various wavelength bands, from optics to hyperfrequency. The benefit of exploiting the synergy between images acquired in various domains appeared quite soon. The present work deals with the fusion of SPOT/ERS images and more particularly on several strategies in fusion. The objective of the fusion, i.e., the application, is prominent as it determines the conditioning of the images and the fusion strategy. Two applications are dealt with aiming at demonstrating the benefit of SAR imagery in fusion in agronomy and snow cover. Fusion of attributes is performed in the first example within a model of vegetation growth. Attributes extracted from images are thematically interpreted. Experience gained in exploitation of optical data is used to understand the attributes obtained from the radar image. Further, the benefit of fusing both sources of attributes is assessed versus using only one source. A first experiment is made with contemporary images and a second one with non-contemporary sources. Assimilating both sources of data reveals beneficial as the number of available radar images is greater than optical images because the latter depend on the cloud cover. The increase of input data in the growth model yields a more detailed description of the growth of the vegetation. The second application calls upon fusion of pixels. This case requests an accurate geometrical superimposition of the images and ancillary data so that interpretation can be performed at pixel level. The range of applications of this type of fusion is considerable. However, exploitation of SAR images in regions with steep relief may reveal difficult. There is no tool to process SAR data for correcting for geometrical and radiometric defects in such case. A processing chain has been created and validated to construct SAR ortho-images. It includes a modelling of the geometry and radiometry of SAR data. Emphasis was put on the detection of landmarks and resampling of irregular grid. Solving accurately these two problems was made possible by a multi-sensor cooperation. Fusion is applied for the conditioning of images and not only on conditioned images. Ortho-images of SAR data acquired in ascending and descending orbits over the Briançon area in the Alps have been built and then processed for the mapping of snow cover. This work contributes to establishing the benefit of SAR images in environmental applications and particularly when fused with optical data.
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Submitted on : Tuesday, April 15, 2014 - 4:41:06 PM
Last modification on : Tuesday, March 27, 2018 - 4:06:18 PM
Long-term archiving on : Monday, April 10, 2017 - 2:04:11 PM

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  • HAL Id : pastel-00979324, version 1

Citation

Luce Castagnas. De la synergie des images satellitaires SPOT/ERS au travers de deux exemples de fusion. Traitement des images [eess.IV]. Université de Nice Sophia-Antipolis, 1995. Français. ⟨pastel-00979324⟩

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