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ROI_pac
Valerie SahakianLaura Sumiejski
SIO 23902/19/2010
What the heck is ROI_pac?
• Takes data• Gets offsets from 2 single-look complex (SLC)
images• Fits 2nd order polynomial to offsets• Resample SLC images (dates)• Multiply complex pixels of images
Gets amplitudes
But…
• Amplitudes form raw interferogram– Topography– Atmosphere– Orbit– Deformation– Etc.
Refine Model
• Removes phase from orbit geometry– Begins flattening
• Calculate correlation between 2 scenes• Removes topography– Calculates and removes phase from DEM
• Subtract models from seismic interferogram• Filter noise, mask (phase variance), unwrap,
etc.
Refine Model cont.
• Re-estimate baseline– Use topography to refine
• Geocoding– Unwrapped phase• Change coordinates over to geographical coordinates to
match DEM
Directory Hierarchy
• Data Directory– Data
• Run Directory– Copies of data– .proc file– DEM directory• DEM
Choose a Location!
• Use EOLi – Earth Observation Link from the European Space
Agency
• For our example we chose an area in Southern California– 35.6° N and 120.28° W• (about 36°36’ latitude and -120°18’ longitude)
Track 256
• Frame 2889• Date 1: Nov.
10, 1992• Date 2: May
17, 1996
Get the Data
• WInSAR– Western North America InSAR Consortium– Data for western US– Members only– Data on WInSAR– Data downloadable from GeoEarthScope and
Supersites
Inputs for ROI_pac: Raw Data
• For ERS1 and ERS2– Assign master and slave
• Master = SARLEADER• Slave = IMAGERY• Note: these files should have the date appended to the
end with the time stamp
– make_raw.pl• Outputs:
– Raw data: date.raw– Metadata for raw data: date.raw.rsc– Reformatted orbit data: hdr_data_points_date.rsc
Inputs for ROI_pac: Parameters
• DEM– Digital Elevation Model • SRTM data
– Mosaic_srtm.pl –Rw/e/s/n magic.DEM
• Process File (.proc)– Int_date2_date1.proc• Radar acquisition dates• Pathname for magic.DEM
But…
• On sioprism.ucsd.edu– /data/ERS1/track/frame/orbit/– /data/ERS2/track/frame/orbit/
• ERS2_track_frame_orbit.zip
• Copy desired data to your directory– Run ers2roi.pl
• Unzips files• Includes make_raw.pl• Makes master and slave files• Makes .proc file
Baseline
• Run base_roi.pl– Acceptable baseline pairs– Perpendicular and parallel baselines– Etc.
• Note: edit path for DEM in .proc file
process_2pass.pl
• Run <process_2pass.pl int_date2_date1.proc>• Wait ~ 1 hour• Magic happens!• To see interferogram– int_date2_date1/flat/ (from after flattening)– <mdx.pl file.unw>
• Note: make sure you ssh using –X or -Y
Success! (sort of)
References
• University of Oregon, WikiRoiPac. http://www.uoregon.edu/~das/WikiRoiPac/doku.php?id=welcome
• Fielding, Eric. ROI_pac Internals: Under the Hood, UNAVCO InSAR shortcourse. August 2009.