Method

ATCOR is the atmospheric compensation program of choice for scientific data processing and analysis.

Atmospheric/topographic correction is the elimination of atmospheric and illumination effects to retrieve physical parameters of the earth’s surface, i.e., the retrieval of surface spectral reflectance, emissivity and temperature. The ATCOR® products solve this task using look up tables, containing radiometric reference data calculated with the MODTRAN®5 radiative transfer code. This approach allows to compensate for atmospheric and radiometric effects in the remote sensing data in a purely physical and reproducible way. Preconditions to this process are:

  • absolute calibration of image data to physical radiometric units (i.e., at-sensor radiance),
  • complete meta data (i.e., acquisition time, location, and observation geometry), and
  • congruent digital elevation data for terrain correction.

Based on this information, a fully automatic processing atmospheric processing may be started. The aerosol contents and the atmospheric water vapor contents are derived from the image itself, depending on the sensor characteristics. The full irradiance conditions for each image pixel are then calculated to derive reflectance information of the ground. The (directional) reflectance is finally retrieved as relation between bottom of atmosphere radiance and the irradiance.