SARVisor: An Integrated Tool to Facilitate SAR Data Selection

In March 2007, the French Space Agency (CNES) and the United Nations Educational, Scientific and Cultural Organization (UNESCO) signed an agreement through which CNES joins the European’s Space Agency – UNESCO’s ‘Open Initiative From Space to Place‘. This initiative invites space agencies, space research institutions and universities to work jointly to bring the benefits of space technologies to developing countries as applied to the conservation, monitoring and documentation of the prestigious World Heritage sites.

The ultimate goal of UNESCO is to make earth observation an integrated and operational tool for the monitoring of World Heritage sites. This paper illustrates the contributions of CNES to the challenging requirements of UNESCO.

Satellite radar data have already demonstrated their capability especially in cloudy areas, or for small movement detection using the interferometry technique. However the selection of adequate acquisition parameters can be difficult in relief area where the geometrical effects of layover, foreshortening or shadow must be taken into consideration.

To facilitate the use of radar data and support UNESCO initiative, CNES decides to provide a tool for SAR visibility prediction. The tool is designed to help users in the selection of the most appropriate SAR data acquisition parameters for the imaging of a particular Area Of Interest (AOI).

CNES appointed Altamira Information to develop the tool. It integrates the main civilian SAR missions (ERS, Envisat/ASAR, Radarsat-1 &-2, ALOS/PalSAR and TerraSAR-X) and selects for each of them the parameters, in terms of acquisition modes and incidence angles, which are the more suitable to cover the considered area. Once the appropriate parameters and a Digital Elevation Model have been chosen, a SAR image is generated, allowing the user to check the visibility of its AOI and thus confirming the selection of the most effective mission and acquisition parameters.

Following some preliminary work conducted at CNES with Envisat data, the sanctuary Machu Picchu (Peru), World Heritage Site of the UNESCO since 1983, constitutes the zone of the tool validation. Due to its location in the highly mountainous area, the site combines all kinds of geometric distortions inherent to the SAR imaging. Layover, foreshortening and shadow will be taken in consideration in order to select the optimum parameters for the SAR observation over this zone.

This tool, as a CNES contribution to the Open Initiative and the SAR users community, is available free of charge.