Geographic Information System, GIS, are very useful in order to view and to process georeferenced images. For the data fusion of Synthetic Aperture Radar images, SAR, with other information sources, one usually uses interferometric processing software to orthorectify the SAR images in order to add them in a GIS. Nevertheless, this projection involves an important alteration of the information of SAR images. In this paper, we propose a simple and efficient method by inverting the process : the radar-rectification of georeferenced data. By coding data from a GIS into the radar geometry , we can use different information sources to improve the analysis of SAR images and the results interpretation. We apply this method on a high relief area in the region of the Mont-Blanc, where SAR images are useful to survey the glacier evolution.