Radiometric correction of topographic effects

  • Madsen, Søren Nørvang (Project Manager)
  • Dall, Jørgen (Project Participant)
  • Dierking, Wolfgang (Project Participant)

    Project Details


    The backscatter coefficient measured by a SAR is inherently normalised by the surface area projected onto the slant range plane. In order to provide the backscatter coefficient normalised by the surface area itself, i.e. the sigma nought value, the local terrain slope must be known and used in a radiometric calibration process. This process must also correct for the fact that the elevation of a scatterer determines the line-of-sight direction and hence the antenna gain to be used in the calibration.
    In 1996 and 1997 a calibration algorithm has been developed and implemented on workstations. It performs a radiometric calibration of a polarimetric EMISAR data set using as input a digital elevation model generated from across track interferometric EMISAR data. The flight tracks from which the polarimetric and interferometric data are acquired must not be too far from another. In addition to the radiometric rectification also a rectification of the terrain induced geometric distortion is accomplished. (Related projects - see:
    Effective start/end date26/04/199531/12/1997