Possible error with reading ASF data azimuth angle

[sar]

I'm using asc_desc2horz_vert.py to resolve up-down and east-west motion for a large area, so instead of using a constant LOS incidence/azimuth angles, I'm using the azimuth file to get a more accurate estimate. However, I don't know if there is a problem with the azimuth file or if I need to add additional parameters for running the script.

If I calculate the motion without the geometry file, the results are:

asc_desc2horz_vert.py asc_velocity.h5 desc_velocity.h5 

read  from file: asc_velocity.h5
calculate the constant LOS incidence / azimuth angles from metadata as:
LOS incidence angle: 37.6 deg
LOS azimuth   angle: 102.6 deg
read  from file: desc_velocity.h5
calculate the constant LOS incidence / azimuth angles from metadata as:
LOS incidence angle: 37.5 deg
LOS azimuth   angle: -102.6 deg

These values make sense and produce reasonable output results:

east-west data range: [-17.406893, 15.187981] mm/year
up-down data range: [-23.816603, 19.174559] mm/year

As per the details in conversation  https://groups.google.com/g/mintpy/c/EcmuJU9jhX0/m/GA63GgvTAQAJ,I've added the lv_phi.tif as the azAngleFile and lv_theta.tif as the incAngleFile.

When running the same command but including the geometry files:

asc_desc2horz_vert.py asc_velocity.h5 desc_velocity.h5 -g asc_geometryGeo.h5 desc_geometryGeo.h5

The results are wrong:

east-west data range: [-739.0742, 695.91144] mm/year
up-down data range: [-232363660.0, 266020430.0] mm/year

I'm using the latest version of MintPy (1.4.1) downloaded from conda.

Attached are plots of the azimuth files after the 'load_data' step.

Any advice on how to fix this would be great.

Thanks

[Zhang Yunjun]

Hi Sar,

The convention of the LOS azimuth angle used in mintpy is defined here (https://github.com/insarlab/MintPy/blob/5eb88579390da078a9f34b9482f01ea17dc360b9/mintpy/utils/utils0.py#L531-L546). As you see there and in your previous run, the normal values are 102 and -102 deg, which are very different from your latest run using lv_phi from hyp3.

The azimuth angle from hyp3 is not examined in mintpy development as far as I remember. Please consider opening a GitHub issue, tagging me and ASF folks, e.g. Joseph, so that we could confirm which files to load and what conversion procedures are needed.

Regards,

Yunjun

[sar]

Thanks Yunjin. 

It was mentioned in the link I posted that MintPy does handle the conversions https://groups.google.com/g/mintpy/c/EcmuJU9jhX0/m/hmSoiv2XAQAJ, so I'll raise a GitHub issue to get it checked.