wktAoi settings for splitting master using snap2stams and master_split_applyorbit.xml


I am trying to use slaves_prep.py for the spliting step of snap2stamps.
As I understood from the code, it takes the tamplet slave_split_applyorbit.xml and put inside the desired parameters, such as IW, INPUTFILE, etc.
I saw there is another xml for the master - master_split_applyorbit.xml with the only difference that it include a <wktAoi>POLYGON</wktAoi> field.

So I used SNAP to get the coordinates that I want (using the Polygon Drawing Tool and then right clicking and choosing “WKT from geometry”).
I then copied it to the xml, but it raises the following error when loading the graph:
Error: [NodeId: TOPSAR-Split] java.lang.NullPointerException

My xml looks like this:

Does anyone see the problem?

Thank you very much,
Oded Horowits

actually, there is no need to manually modify the xmls. You only define the config file (including the coordinates of the AOI) and the python scripts call the xml files handing over these paramers. These xmls are not meant for manual execution

Thank you for your response.
The manual of snap2stamps at chapter 4 lists the python scripts to use. Since it doesn’t refer to the master at all, I figured that I need to add something…

I will try it by adding borders in the config file.

Hello again,
I did not changed the XML - but the .py file.
Since I saw that the master should be placed in another folder named “PROC/master” (whereas the slaves are in “PROC/slaves”), I thought - how would the splitting_slaves.py split the master if it has no refference to the master folder?
So I change the py file to cause the spliting graph xml of the master to include the polygon coordinates…
Am I doing it right?


actually, none of the scripts should be modified. You define the paths, the master file and the AOI coordinates in the config file alone.

The more you manually modify the scripts, the higher is the chance to mess something up.

Ok, so -
At the very beggining - should I put the master in the PROC/slaves with all the slaves?
And let’s say I do, and run slaves_prep.py and splitting_slaves.py like that,
what should I put in line #9 of the config file (MASTER=) - the splitied mater file from the created split folder?

Thank you

for MASTER you set the full path to the prepreocessed (_Split_Orb.dim) master image
don’t include the master in the slaves folder.

Please see the tutorials here:

Also the first couple of posts in this topic explain how to use the scripts: Snap2stamps package: a free tool to automate the SNAP-StaMPS Workflow

:clap: :clap: :clap: :clap:
That helped me SO MUCH!
I have been searching this forum for days, spending hours on reading long posts, and only now I understood how to do that correctly!!
Thank you very much!

Oded Horowits

Sometimes it’s just knowing where to look :+1: