Hello SNAP forum,
I am attempting to orthorectify and terrain correct S1 IW imagery using the attached batch processing graph (step1), before i test some speckle filters (step 2). As displayed in the command line interface below, i receive an error stating there are" not enough valid GCP’s for the warp" during the cross correlation process. The result is a blank screen in SNAP when displayed for all bands (except for the local and projected incidence angle). I have changed the number of GCP’s from a range of 200 up to 2000 points, but i still receive the same error. If you examine the xml graph attached you will see I am using an external DEM and a subset in this process as well; when i do not subset, the SAR simulation/ cross correlation works with no GCP error regardless of the GCP setting.
Is the source of this error another parameter in the Cross correlation setting ? Or, is this a subsetting compatibility issue with my current process? I would prefer to keep the subset node in place to reduce processing time.
Thank you for any suggestions & advice
STEP1_S1.xml (6.5 KB)