Hi, I tried to geometric correct cosmo-skymed data using sar-simulation terrain correction technique but my output is black (nothing). Could anyone tell me why?
this can have several reasons. Please give us information on the following questions.
- No auto-download DEM is available in your area (where is it located?)
- SNAP cannot access the DEM directory (some things changed recently, are you sure you have installed all updates?)
- No topographic patterns are reflected in your intensity (do you have topography within your area?)
- The spatial resolution of the downloaded SRTM doesn’t reflect the variations in the image (which one did you select and what’s the spatial resolution of yur CosmoSkyMed data?)
- DEM is available at Skudai, Johor, Malaysia
- Yes, I ave installed recent updates
- Yes, my area have topography
- I downloaded the 90m SRTM and my spatial resolution of COSMO-SkyMed is 3m
you could reduce this discrepancy by using the SRTM 1 ArcSec (AutoDownload) which has a spatial resolution of 30 meters. If the patterns in the image are not represented by landforms in the simulated image, the coregistration fails. As a check, you can run the SAR Simulation (without TC) and have a look at the simulated SAR image. If it is comparable to your input data the terrain correction should work.
Otherwise you will have to go for Range Dopper Terrain Correction.