Terrain Flattening Operator
When land cover classification is
applied to terrain that is not flat, inaccurate classification result
is produced. This is because that terrain variations affect not
only the position of a target on the Earth's surface, but also the
brightness of the radar return. Without treatment, the radiometric
biases caused by terrain variations are introduced into the coherency
and covariance mstrices. It is often seen that the classification
result mimic the radiometry rathen than the actual land cover. This
operator removes the radiometric variability associated with topography
using the terrain flattening method proposed by Small [1] while leaving
the radiometric variability associated with land cover.
Parameters Used
The following processing parameters are used for this operator:
- Source Bands: source product bands. User can select one or
more bands for terrain flattening. If no band is selected, by default
all bands are selected for terrain flattening.
- Digital Elevation Model: available digital elevation models used in computing local illuminated area.
- DEM resampling Method: resampling method used in getting elevation from DEM.
Reference:
[1] David Small, "Flattening Gamma:
Radiometric Terrain Correction for SAR imagery", IEEE Transaction on
Geoscience and Remote Sensing, Vol. 48, No. 8, August 2011
