Graph builder / gpt bug


I encountered something that seems to be a little bug while working with the graph builder and gpt.

Following scenario:

I’m creating a graph inside SNAP using the graph builder which I then save to an xml file for running it with gpt. So far so good.

When creating the graph, I remove the Read operator and replace it with a ProductSet-Reader, in order to read a bunch of files for e.g. Coregistration.

When I then save the completed graph to xml, the ProductSet-Reader node seems to be added to the end of the chain. At first it didn’t seem like a big thing since the source referencing is still ok. But gpt fails to execute the graph returning an error for missing source product.
When I then manually move the node to the start of the chain (aka. the top of the file), the graph is executed just fine.

So it might not be a biggie, but it probably isn’t either to patch in a next release (that is if it’s indeed a bug ;)).

For the sake of completeness:

  • OS: Windows 7 x64
  • SNAP: V 5.0



This sounds familiar to me. Actually it should not be of any importance if the ProductSet-Reader is defined first or last or somewhere in between.

@lveci Can you have a look?

SNAP 6.0 - ProductSet-Reader must still be first in the graph to avoid error/failure. You must manually move ProductSet-Reader to the top of the graph. Note that editing and saving graphs with GraphBuild may move ProductSet-Reader, also requiring moving back to top. I have experienced this on Linux.

This was still an issue with SNAP 7.0, but appears to now be fixed in SNAP 8.0.

1 Like