sarproz-group

Persistent Scatterers steps and interferograms generation

This topic contains 7 replies, has 4 voices, and was last updated by  agoorabi 3 months, 3 weeks ago.

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  • #697

    periz
    Keymaster

    While waiting for more documentation to come,
    I open a new topic on this matter for the newcomers.
    In Sarproz, Persistent Scatterers interferometry is applied to un-filtered full-resolution data.
    This means that you do not need to generate interferograms if you want to process Persistent Scatterers.
    It is suggested to process interferograms if you want to carry out weighted multi-temporal approaches (like quasi-PS).
    In such case, before processing the interferograms, you have to choose from the “dataset selection” window the images graph that you want to process.
    For classical PSI, these are the steps to follow (as mentioned in the notes by Timo http://www.sarproz.com/by-timo-balz/)
    – preliminary analysis (section 1.4.1 of the manual)
    – preliminary geocoding (1.4.2)
    – phase2height and phase2flat constants generation (1.4.3.2 and 1.4.3.3)
    – APS estimation (1.4.6.1)
    – Sparse Points processing (1.4.6.2)

  • #3634

    volkan
    Participant

    Hi,

    I want to apply PSInSAR with these steps. But I have some questions.

    phase2height and phase2flat constants generation (1.4.3.2 and 1.4.3.3) are not generated manually according to the following link. In which step it is done by automatically?
    https://www.sarproz.com/groups/sarproz-group/forum/topic/sarpros-release-2017-2/

    This entry posted at earlier 2015 and many updates have come to Sarproz up to the present. So, for the last version of Sarproz, could we sort the steps as follow:

    – preliminary analysis (section 1.4.1.1 – 1.4.1.2)
    – preliminary geocoding (1.4.2.1 – 1.4.2.2 – 1.4.2.3 – 1.4.2.4 – 1.4.2.5)
    – APS estimation (1.4.8.1)
    – Sparse Points processing (1.4.8.3)

    https://www.sarproz.com/software-manual/

  • #3636

    periz
    Keymaster

    phase2height and phase2flat constants are automatically generated when needed.
    if you check the log, you will find it written.

    1.4.2.5 is coregistration refinement and you should NOT run it in normal conditions https://sarproz.com/manual/coreg_refine.html

    APS estimation (1.4.8.1) + Sparse Points processing (1.4.8.3) is the standard approach.
    However, is some cases it could not work (e.g. when the movement exceeds the unwrapping condition).
    In such cases, you could stop at the APS processing. Or you could use the optional Graph Analysis and refinement module (1.4.8.2) https://sarproz.com/manual/graph_refinement.html

    For data import and preliminary analysis, there are multiple tutorials here (they are in chronological order) https://www.sarproz.com/tutorials/
    To start with InSAR time series, follow this tutorial: https://www.sarproz.com/publish/QYTutorial4.pdf

    • #3891

      agoorabi
      Participant

      Hi,
      Where is the ” phase2height and phase2flat constants generation (1.4.3.2 and 1.4.3.3)” step?

  • #3647

    volkan
    Participant

    Thank you for the detailed answer. I applied as follows;

    – Preliminary Analysis (1.4.1.1 Reflectivity Map – 1.4.1.2 Mask Generation),
    – Preliminary Geocoding (1.4.2.3 GCP Selection – 1.4.2.4 Ext. DEM in SAR Coordinates),
    – Multi-Image InSAR Processing (1.4.8.1 APS estimation – 1.4.8.3 Sparse Points Processing)

    and after these steps, I used load mask, scatter plots and time series module to visualization.

    I have some questions at this point. There are several PSI algorithms like QPS, SBAS, StamPS and Squeesar. And incredibly Sarproz is capable of do all these methods. Are these steps belongs to which PSI method?

    If I want to apply QPS to my study area, my roadmap should be how?

    • This reply was modified 6 months ago by  volkan. Reason: link edit
  • #3691

    periz
    Keymaster

    It looks like somehow my previous answer to this post went lost…
    In your recap you list 3 main steps.
    The first 2 are common to all Time-Series approaches.
    The third one corresponds to the classic Persistent Scatterers method.
    If you want to apply other methods, you might need to process interferograms first.
    Also, in some cases you do not use the Sparse Points Processing module, but you might use the Graph Analysis and Refinement module.
    We do not provide a roadmap for all these alternatives, because you have many options depending on your case (sensor, number of images, analyzed area, type of movement and so on).
    However, we are collecting processing cases that we sometimes share (many of them cannot be published because data are sensitive).
    You can find more hints here:
    https://www.sarproz.com/groups/sarproz-group/forum/topic/qps-with-dem/
    https://www.sarproz.com/groups/sarproz-group/forum/topic/original-ps-method/
    best

  • #3889

    vale705
    Participant

    Hello,
    I am trying to process 32 Sentinel SAR images and to use PS-Interferometry on it. The area that I want to process is a small area (about 1km2) and I would like to know if I am following the correct procedure. These are the steps that I have followed after having loaded and co-registered my data:
    – In the Site Processing panel I perform the Preliminary Analysis (Reflectivity Map + Mask Generation) and the Preliminary Geocoding (GCP Selection + Ext. DEM in SAR Coordinates);
    – In the Small Area processing panel I select the Area of Interest using the Grab option and then I apply in order the Sparse Points Selection, the Multi_image InSAR analysis and the Geocoding.
    Am I missing any steps or doing anything wrong?
    Many thanks for you help and best regards

  • #3890

    periz
    Keymaster

    nothing is wrong. yours is the simplest and most straightforward approach for analyzing a small area.

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