sarproz-group

cumulative displacement. Load mask error

This topic contains 3 replies, has 2 voices, and was last updated by  periz 3 weeks, 5 days ago.

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  • #2349

    leewoneung
    Participant

    I can’t select cumulative displacement at Load mask.
    If I select cumulative displacement, I have only 0 selected points.
    before the select cumulative displacement at Load mask, I seleceted Amp. Stab. Index 1-Sigma/Mu, and Temporal coherence. and I finished APS estimation and Sparse Points Processing. I checked Linear Trend and Height estimate at APS estimation and Sparse Points Processing step.

    But, I can’t select cumulative displacement at Load mask.
    only I do get CumDisp.mat not found.

  • #2350

    periz
    Keymaster

    1. select a set of points via load mask using e.g. the temporal coherence or the amplitude stability index. it does not make any sense to select points based on cumulative displacement

    2. then check your results via histogram and scatter plots modules. you can check the histogram of the cumulative displacement to understand what is wrong. then you can plot it in SAR (or geographic) coordinates using scatter plots. in both modules you can apply additional sub-selections of points using the boolean conditions. Here you see examples of the use of histograms and scatter plots http://www.sarproz.com/publish/tutorials_partIII.pdf

    3. if the cumulative displacement CumDisp.mat file is not there, it means it was not saved. Is the velocity there? If the velocity is there and the cumulative displacement not, it means you estimated a linear model, so, the cumulative displacement was not produced. To know to cumulative displacement, just multiply the velocity by the observation time. If the velocity is not there either, it means you did not save your results.

    • #2351

      leewoneung
      Participant

      3. if the cumulative displacement CumDisp.mat file is not there, it means it was not saved. Is the velocity there? If the velocity is there and the cumulative displacement not, it means you estimated a linear model, so, the cumulative displacement was not produced. To know to cumulative displacement, just multiply the velocity by the observation time. If the velocity is not there either, it means you did not save your results.
      ========
      What can I save velocity?
      or
      if velocity equals def.trend, I got the velocity.
      if I have a linear model, so I couldn’t cumulative displacement,
      How can I get cumulative displacement???
      ….
      I read manual dozens of times But I don’t understand “cumulative displacement” step.

  • #2352

    periz
    Keymaster

    Yes, velocity and deformation trends are the same.
    The cumulative displacement is saved when you do a non-linear processing.
    You do a non-linear processing if you input a value in the “smart” box in the time series processing options.
    That value corresponds to the length of a temporal filter. So, the outcome is a non-parametric estimation of the time series.
    If you use a linear model, the cumulative displacement is not saved as a default. But if you use a linear model, the cumulative displacement is easily calculated from the velocity. So, displaying the velocity or the cumulative displacement (in the linear model case) is absolutely equivalent.
    If you want to see that value in mm, you can do it manually yourself and create a cumulative displacement file. You can then import the file and plot it.

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