09 config snaphu - unavco · 2017. 2. 25. · resulting cost functions are based on the assumption...
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GMTSAR Config File and More About SNAPHU
by Xiaohua Xu
GMTSAR Config Files � /GMT5SAR/gmtsar/csh/ ◦ config.alos.slc.txt SLC_factor ◦ config.alos2.slc.txt SLC_factor ◦ config.envi.txt ◦ config.rs2.txt ◦ config.alos.txt ◦ config.csk.txt ◦ config.ers.txt ◦ config.tsx.txt ◦ config.s1a.txt
Config File Example ##################### # processing stage # ##################### # 1 - start from preprocess # 2 - start from focus and align SLC images # 3 - start from make topo_ra # 4 - start from make and filter interferograms # 5 - start from unwrap phase # 6 - start from geocode proc_stage = 1
Preprocessing ################################## # parameters for preprocess # # - pre_proc.csh # ################################## # num of patches num_patches = # earth radius earth_radius = # near_range near_range = # Doppler centroid fd1 =
Focus and Alginment
� No parameters But
◦ FBD FBS (Fine Beam Double/Single Polorization)
◦ fitoffset.csh #
Remove Topographic Phase ##################################### # parameters for make topo_ra # # - dem2topo_ra.csh # ##################################### # subtract topo_ra from the phase # (1 -- yes; 0 -- no) topo_phase = 1 # if above parameter = 1 then one should have put # dem.grd in topo/ # topo_ra shift (1 -- yes; 0 -- no) shift_topo = 1
Generate Interferogram ######################################## # parameters for make and filter interferograms # # - intf.csh # # - filter.csh # ######################################## # switch the master and slave when doing intf. # put "1" if assume master as repeat and slave as reference # put "0" if assume master as reference and slave as repeat [Default] # phase = repeat phase - reference phase switch_master = 0 # look at the filter/ folder to choose other filters filter1 = gauss_ers_200m (Will be replaced by make_filter.c) # Set the decimation to be 1 if you want higher resolution images. # Set the decimation to be 2 if you want images with smaller file size. # dec_factor = 1
Unwrapping ##################################### # parameters for unwrap phase # # - snaphu.csh # ##################################### # correlation threshold for snaphu.csh (0~1) # set it to be 0 to skip unwrapping. threshold_snaphu = 0.12 # region to unwrap in radar coordinates # example 300/5900/300/25000 region_cut = # mask the wet region (Lakes/Oceans) before unwrapping (1 -- yes; else -- no) switch_land = 1
Unwrapping # Allow phase discontinuity in unrapped phase. This is needed for interferograms having sharp phase jumps. # defo_max = 0 - used for smooth unwrapped phase such as interseismic deformation # defo_max = 65 - will allow a phase jump of 65 cycles or 1.82 m of deformation at C-band # defomax = 0
Geocoding ##################################### # parameters for geocode # # - geocode.csh # ##################################### # correlation threshold for geocode.csh (0~1) threshold_geocode = 0.12 (For different resolution output, modify the output grid size of blockmedian in proj_ra2ll.csh)
More About Unwrapping
SNAPHU
� Statistical-cost Network-flow Approach for Phase Unwrapping ◦ Chen & Zebker (Stanford) ◦ Residual (not analytical / Integration depend
on path)
SNAPHU � snaphu phase.in -c corr_file -f config_file -o output_file -v -s/-d � -s
Run in smooth-solution mode. The problem statistics and resulting cost functions are based on the assumption that the true unwrapped phase represents a generic surface with no discontinuities.
� -d Run in deformation mode. The problem statistics and resulting cost functions are based on the assumption that the true unwrapped phase represents surface displacement rather than elevation.
� DEFOMAX Maximum phase discontinuity likely (double). Units are radians or cycles. If abrupt phase discontinuities are not expected, this paramter can be set to zero.
Unwrapping of Large Rupture
snaphu.csh � Masks ◦ Landmask (phase) ◦ Correlation Mask (corr) ◦ Fault Mask (correlation) (User Definied)
� SNAPHU ◦ defomax = 0 (not a rupture) ◦ defomax = ## (rupture)
� Detrending ◦ whether there is an rupture
� plotting
Fault Mask
Fault Mask
� Create a polygon file in Google Earth � Use kml2gmt to generate the gmt file � Use grdtrack to get the topography from
dem.grd � Use “SAT”_llt2rat to project the polygon
into radar coordinates � Use grdmask to generate a mask called
mask_def.grd (copy to the intf folder)
Test case for Landers
−117˚30'
−117˚30'
−117˚00'
−117˚00'
−116˚30'
−116˚30'
34˚30' 34˚30'
35˚00' 35˚00'
C
C’
B
B’A
A’
−80
−60
−40
−20
0
20
40
60
80
cm
Test case for Landers
Questions?