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dbekaert / StaMPS

Stanford Method for Persistent Scatterers
http://homepages.see.leeds.ac.uk/~earahoo/stamps/
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Sign Convention for Plotting Velocity and Phase #36

Open hariiirs opened 1 year ago

hariiirs commented 1 year ago

I am confused with the sign convention of velocity and phase retrieved from StaMPS processing using ascending and descending passes. What should be the sign conventions for the following situations-

Ascending Data 1) If reference image predates the secondary image- what is the meaning of positive and negative velocities and phase 2) If reference image postdates the secondary image-what is the meaning of positive and negative velocities and phase 3) If reference image is in the middle of all the secondary images - what is the meaning of positive and negative velocities and phase

Descending Data 1) If reference image predates the secondary image- what is the meaning of positive and negative velocities and phase 2) If reference image postdates the secondary image-what is the meaning of positive and negative velocities and phase 3) If reference image is in the middle of all the secondary images - what is the meaning of positive and negative velocities and phase

Please help me if you know it. I am using StaMPS-master (Version 4.1b).

Thanks in advance Hari Shankar

ranneylxr commented 10 months ago

Hi Hari, Do you know the answers? I am also confused with the sign convention of velocity and phase retrieved from StaMPS processing. Thank you very much! sincerely, Xiaoran.

constantinevi6 commented 10 months ago

Hello, Following the code in ps_output.m, here is the summary: No matter what As or Des orbit, velocities with positive value mean uplift / close to the satellite, negative mean subsidence / away from the satellite.

And phase (using ps_plot('u-dm') in MATLAB) with positive value means subsidence / away from the satellite compare to the reference date. Negative means uplift / close to the satellite compare to the reference date.

note that the output .xy file from ps_output.m will convert phase to accumulated displacement in mm, in this file: positive value means uplift / close to the satellite compare to the reference date, negative means subsidence / away from the satellite compare to the reference date.

If I have any mis understand, please let me know, thank you.

hariiirs commented 10 months ago

Yeah

The explanation regarding sign convention is correct provided reference images is predated with the secondary images.

Regards Hari Shankar

On Tue, 19 Sept 2023, 08:00 ranneylxr, @.***> wrote:

Hi Hari, Do you know the answers? I am also confused with the sign convention of velocity and phase retrieved from StaMPS processing. Thank you very much! sincerely, Xiaoran.

— Reply to this email directly, view it on GitHub https://github.com/dbekaert/StaMPS/issues/36#issuecomment-1724741607, or unsubscribe https://github.com/notifications/unsubscribe-auth/AKDZGJIZRNU7BDYDLKJR64DX3D7URANCNFSM6AAAAAAQN75TQU . You are receiving this because you authored the thread.Message ID: @.***>