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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 2 years ago

hariiirs commented 2 years 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 1 year 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 1 year 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 1 year 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: @.***>