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Radiometric terrain correction
Added by René Mania over 7 years ago
Hello,
I have descending data from two different spotlight tracks (TSX/TDM) of the same area and I would like to compare the amplitude information of both over time. Is there any way to perform a radiometric terrain correction in GAMMA? If so, what would be the recommended workflow?
Regards,
Rene
Replies (1)
Radiometric terrain correction - Added by Charles Werner over 7 years ago
Hello,
Yes you can terrain geocode the detected radar image with Gamma software. That
the data are spotlight mode does not complicate the terrain geocoding process.
It is the same as with any SAR image. Having a high resolution DEM is highly
recommended because the resolution of spotlight data is very high. (better than
1 m). I personally use the mk_geo_radcal script to perform the terrain correction.
See the documentation in DIFF/html/mk_geo_radcal.html:
gamma_doc mk_geo_radcal
When performing the radiometric correction I would use the options -p -c
If working with geographic coordinates (latitude and longitude) add the -z option.
The DEM has to be in GAMMA format, that means there has to be DEM parameter file
and the DEM data specified in meters for the heights, generally as single
precision big-endian floating point format.
The ellipsoid should be WGS84 for the height data , i.e. this means that SRTM
DEM data that are geoidal heights (referenced to the geoid) have to be converted
to ellipsoidal heights reference to the WGS84 ellipsoid. The Gamma script
srtm2dem can do this conversion to the Gamma format and correction for the
difference between the ellipsoid and geoid. see $DIFF_HOME/html/srtm2dem.html
or enter:
gamma_doc srtm2dem
Regards, Charles