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?