sarproz-group

Phase unwrapping after APS removal

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    • #5022
      ewid
      Participant

      Dear SARPROZ community,
      after processing the APS module I didn’t find a way to unwrap this corrected Interferogram. I followed for most parts the tutorial “Atmospheric Delay Mitigation on Single (or few) Interferograms” but I did not do the Multi-looking. I checked the “Stratif.”-Box in the APS-options. I could export it as tif and as jpg file but it seems to me that the other files (contained in the INTERFEROGRAMS folder) which are normally produced when processing an interferogram are missing (.log, Mask_, coher.jpg, etc…). I’m working with TerraSAR-X data and to process just one interferogram based on an graph (Delaunay, etc.) I took just 2 scenes in the SLC folder. I hope I was precise enough.
      Best,
      Eva

    • #5025
      periz
      Keymaster

      Hi Eva,
      you are using the sw in a way we did not think of. Now (it’s an option we introduced about 8 months ago), you can remove the APS from interferograms (in the InSAR module) at the time of exporting your results (which means, after processing them). [in fact, this option is present also in the view/export extended parameters module] In other words, you cannot unwrap the interferogram after removing the APS. Firstly, you unwrap it, later (when you export it in geotiff or kml), you remove the APS.
      You can remove the APS and then process the phase only in the Multi-Temporal modules.
      We’ll think about your case.
      In the meanwhile, I suggest you do this manually in matlab. You should read the interferogram, read the APS, remove the APS from the interferogram, make a backup of the interferogram, save the result with the same name of the interferogram. Then you can use the “read interf” option to load it in the sw and unwrap it. For reading and writing, search in the forum “leggi” and “scrivi”. Careful that the APS is downsampled. The APS file size is stored in the APS folder.
      best

    • #5033
      ewid
      Participant

      Dear Prof. Perissin,
      thank you for your quick reply! I tried to follow your advice to do it manually in Matlab with leggi and scrivi. With the leggi function it could read the data (Matlab showed all the values in the lines) but when I wanted to plot the Data (with plot(Data)) there were strange figures which did not correspond to the interferogram. I typed the following:
      Data=leggi(‘E:/…./INTERFEROGRAMS/…..’,9040,12590); (numbers vor S and L which I looked up with “fast”)
      Data=leggi(‘E:/…./INTERFEROGRAMS/…..’,9040,12590,[],1,1) (numbers for type and view). Probably there is a variable missing?
      Best,
      Eva

    • #5034
      periz
      Keymaster

      Data=leggi(‘E:/…./INTERFEROGRAMS/…..’,9040,12590,[],1);
      disec(angle(Data))
      dise(abs(Data))

      >> help disec
      disec(x)
      disec(x,fact)
      f_norm=fact*max(x(:));
      f_norm_min=fact*min(x(:));
      if input is uint8, x is plotted between 0 and 255 and f_norm tells the colorbar range
      disec(x,[inf sup])
      disec(x,fact,fig) fig figure number (se =0 lancia figure; se vuoto niente)
      disec(x,fact,fig,q) if q colorbar
      disec(x,fact,fig,q,labX,labY,tit) labels and title
      disec(x,fact,fig,q,labX,labY,tit,qtit) colorbar title
      disec(x,fact,fig,q,labX,labY,tit,qtit,map) color map (‘reverse’ for velocity)
      disec(x,fact,fig,q,labX,labY,tit,qtit,map,aa) axis auto (default 0)
      disec(x,fact,fig,q,labX,labY,tit,qtit,map,aa,fr) color freezing (default 0)
      qq=disec(x)
      disec(x,params)
      [qq,fig]=disec(x)

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