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Elevation Modeling and Displacement Mapping using Radar Interferometry

Remote Sensing

  1. Didier Massonnet

Published Online: 15 SEP 2006

DOI: 10.1002/9780470027318.a2304

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Massonnet, D. 2006. Elevation Modeling and Displacement Mapping using Radar Interferometry. Encyclopedia of Analytical Chemistry. .

Author Information

  1. Centre National d'Etudes Spatiales, Toulouse, France

Publication History

  1. Published Online: 15 SEP 2006

Abstract

Topographic modeling consists of producing a digital description of the relief of a given area. This description is generally given on a regular grid in two coordinates. The product consists of the value of the altitude of the terrain for each position of the grid, with respect to a reference shape such as an ellipsoid (approximation of the shape of the Earth) or the geoid (shape of the potential of gravity at sea level). The grid itself is defined in a cartographic or a geographic coordinate system. Common systems include the Universal Transverse Mercator (UTM), Lambert or, alternatively, coordinates in latitude/longitude. Topographic data are used in a variety of applications, from the correction of geometric distortion in remote sensing images to the prediction of the volume of materials to be removed in public works. Their applications include military uses, such as collision avoidance for low-flying aircraft or missiles, or civilian ones, such as optimal positioning of transmitters to cover an area for mobile communications. Radar interferometry is a promising technique for producing topographic maps on a large scale. It makes use of the very peculiar features of the images produced by synthetic aperture radar (SAR) instruments placed on board satellites. Used in differential mode, this technique can also produce a unique product: the map of the displacements which occur in a given area between two passes by a radar satellite. Again, the data can be organized as a digital file placed on a grid similar to the ones used for topographic mapping. However, in the case of displacement measurement, the useful piece of data placed on each node is the displacement experienced by the node, expressed in appropriate units of length. As for each new technique, there are a number of points to take care of before interpreting the data. The purpose of this article is to describe the radar data, both historically and technically, and to detail their two main applications in topography and displacement mapping. The main issues of the interpretation and the availability of the data are covered. Finally, we compare the performance of radar interferometry with other techniques, in both domains, and we try to outline its future.