sarproz-group

Sentinel-1A coregistration problem

This topic contains 4 replies, has 3 voices, and was last updated by  Yuxiao 3 months, 2 weeks ago.

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  • #2155

    bridgetwang
    Participant

    Dear all,

    I encountered with these warnings in the coregistration step for sentinel1-A.

    Could you please tell me the reason and how to correct it ?

    Thank you so much.

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  • #2158

    periz
    Keymaster

    Dear Bridget,
    it is always useful to include the full log file in order for us to read more infos and better understand your case.
    It seems to me that both issues should belong to an old software version, the last update should have solved them.
    In any case, none of them represent a real problem for the success of the processing.
    Please check you result and if no evident issues are visible, you can proceed in your analysis.
    If some other problems are found, please try firstly to update the code.
    Otherwise, get back to us.
    all the best

  • #2161

    bridgetwang
    Participant

    Dear periz,

    Thank you very much for the answer, I updated the software and the coregistration work successfully.But I didn’t find the log file for coregistration.

    Also as I just complete the coregistration, although the matlab reports that the coregistration was concluded succesfully, I saw that for one image there is warning information. I put the screenshot and the Coreg-Resamp log of that image in EXT folder as attachment. Is the coregistration for this image fail? If I want to improve the coregistration for this image, How can I do it ?

    and I also saw that several image got “Burst 8&9 Cross-Interf TOO NOISY. Set to 0!”. Will it influence the coregistration?

    One big problem for me is that I almost don’t know how to change the parameters in “Co-reg.param” part.

    Thank you very much.

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    • #2166

      Yuxiao
      Moderator

      Hi Wang,

      First of all, thank you for taking a carefully look at the log before processing the data to the next step.

      Sentinel uses a method called spectral diversity (SD) for coregistration in order to meet the strict restriction of Sentinel TOPS coregistration. To give a simple explanation it uses the spectrum of TOPS for coregistration.

      As a result, if we need the spectrum of TOPS for coregistration we need a good coherence to guarantee the coregistration.

      “Burst n & n+1 is too noisy……” means the area for doing (SD) between those two bursts have a very low coherence, so we are not able to extract enough information to do a robust spectral diversity. As a result, we are doing some “compromises” there. And we give a warning.

      For your particular case, it should be fine, you can carry on.

      If you are looking for a more detailed/technical explanation you could contact me. Here I just try to give an intuitive explanation of what is going on.

      That first big and long warning is a bug (it shouldn’t be there) and I will fix it now.

      the log file is called “site.log” and is in your data folder.

      yuxiao

  • #2164

    bridgetwang
    Participant

    here is the log file.

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