Two Sentinel-1 SLC scenes cutting the area of interest: S1 TOPS merge and slice assembly operators

Dear all,

I am trying to produce a coherence map but the edge between 2 Sentinel-1 acquisitions is right over my area of interest. Besides, the same area is right in between two subswaths IW.
Therefore, in order to cover the entire area, I guess I have to merge first the 2 subswaths and then to apply the “slice assembly” operator between the two scenes.

Here my processing chain:

  • S1 TOPS splits (to choose only the bursts of interest in any subswaths)
  • Apply Orbit file (applied to any selected bursts in the previous step)
  • S1 TOPS Deburst (applied to any selected bursts)
  • S1 TOPS merge (to merge 2 adjacent subswaths from the same scene)
  • S1 TOPS slice assembly (to mosaic the merged subswaths from the previous steps)

After that, I would coregister the two acquisitions taken 6 days apart but, at the last step, I get the following error:

[nodeID: slice assembly] string index out of range: 5

First of all, is my processing chain correct? How shall I handle two scenes which are cutting my area of interest?

Second point: if the processing is correct, what does the error mean?

Waiting for your suggestions.
Thanks a lot,


Hi michelle,

S1 TOPS slice assembly operator is used for assemblying scenes from the same acquisition.

You should use it from two S1products that can be “paste” together to become one product. then you can work with this result as one S1product that is 2 times bigger.

1 Like

Dear AriJeannin,

thanks a lot for your reply.
If I properly understand, I must firstly apply the “slice assembly” operator in order to mosaic the two scenes, and create one bigger product. After that, I can proceed with the typical steps (S1 TOPS split, apply orbit). I will do this for two different dates and then I will be able to make the coregistration. Is it correct?


I don"t really get you issue.

For Coherence map you need 1 master image and 1 slave image.
You can follow those steps for a better understanding:

If your area of interest is sliced within 2 masters and 2 slaves, you can apply S1 TOPS slice assembly to get one master composed with 2 S1products and again S1 TOPS slice assembly to get one slave of the 2 S1products.
Then you can work with them as one master and one slave like in tutorials

Last part of your message confirms me that I understood properly your indication.
Thanks a lot!