IDEPIX in SNAP 7 failing for high latitude MSI scenes

snap Problem Reports
#1

Hi,

I’m having a problem where Idepix is failing for MSI scenes > 60 degree latitude when “compute cloud shadow” is selected. I receive the error message:
“Entire image is outside of SRTM valid area. Please use another DEM”
That would be fine if I was using the SRTM DEM but I’m using the GETASSE30 DEM, which should cover these regions. Any suggestions how I can get Idepix working with cloud shadow in these high latitude regions?

I get the error when using either the GUI or command line gpt command.

#2

Try a different DEM such as ASTER or the CDEM (if you’re in Canada).

#3

Thanks for the suggestion but I have tried with all the SNAP supported DEMs and get the same error message about SRTM. I think in the cloud shadow routine it must be hard-coded to use SRTM.

#4

Hi.
You’re right, there was a part that prevented that other DEMs than SRTM were used. This has been fixed and will be included in the next idepix update.
There is a workaround you can immediately use, though: The Idepix will use already existing elevation bands, so it should work if you first add the elevation band (using the AddElevationOp when you have a Graph or “Add Elevation Band” from the context menu in the product tree) and then run the Idepix.

EDIT: This affects only the Cloud Shadow. The pixel classification is done on the base of the user-given DEM and when you switch off the Cloud Shadow Computation everything will work.

#5

That’s great. Thanks.