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ROI_PAC processing for Modern Geodetic Methods (Page 5 of 6)

Creating Figures:

If all goes well, there are only one or two figures that you may want to create: the final interferogram with all modeled orbit and topography removed, and the final unwrapped interferogram with values in LOS deformation.

Creating Interferogram plot:

Unfortunately, the process_2pass.pl script can work so automatically that it doesn't by default generate an interferogram file that is georeferenced and ready to image with other software such as GMT. Thus, we will need to do a couple of file conversions before we start plotting.

Be sure you're in the correct Directory

% newgrp MGM
% cd ~/MGM/HectorMine/int_990915_991020/

Convert the interferogram from a complex to hgt format.

% cpx2rmg.pl filt_990915-991020-sim_ODR_4rlks.int filt_990915-991020-sim_ODR_4rlks.int.hgt

Now, we must geocode the interferogram (convert it from satellite to an earth reference frame) using the 'geomap_4rlks.trans' transformation grid.
```
% geocode.pl geomap_4rlks.trans filt_990915-991020-sim_ODR_4rlks.int.hgt geo_filt_990915-991020-sim_ODR_4rlks.int.hgt 
```
Be careful to only transform files with the same number of looks (e.g. 4rlks) as the program will assume so, and perform a blind pixel-by-pixel transformation. In order to downsample a raw sized image to one that matches your current transformation grid use 'look.pl'.
```
% look.pl 990915-991020.int 4  # this will create 990915-991020_4rlks.int
```
We will also need to convert the HGT format used by ROI_PAC to a grid format read by GMT. This will require matlab, and can be done either by bringing up a matlab window or calling the commands directly from the command line. I show the later here because of its expediency. Matlab simply calls a couple of simple scripts that I wrote called wrap2grd and internally readforwrapped to convert the input file into a NetCDF file for GMT.
The format for wrap2grd is:
```
             wrap2grd(AP,infile,outfile)
                 AP = 0=Amp, 1=Phase
                 infile = hgt inputfile (must have .rsc file too)
		 outfile = output NetCDF file
```
Looks like the grdwrite component of wrap2grd doens't work on the newest version of matlab. Use matlab2010 on PELE!!
```
% matlab  -nosplash -nojvm -nodesktop  << EOF
    addpath '/home/anewman/InSAR/matlab_common'
    wrap2grd(1,'geo_filt_990915-991020-sim_ODR_4rlks.int.hgt','geo_filt_990915-991020-sim_ODR_4rlks.int.hgt.grd');
EOF
```
Now we will copy over and run a GMT script, HMwrapped.gmt written specifically for the Hector Mine region. A version of this script can be easily enough modified to plot interferograms for any region.
```
% cp ~anewman/MGM/HectorMine/int_990915_991020/HMwrapped.gmt .  # copy my version so you can later modify it
% HMwrapped.gmt geo_filt_990915-991020-sim_ODR_4rlks.int.hgt 
```

To create a high resolution png image file suitable for viewing rapidly online you can run pstoimg. Here, I am forcing the image density in dots per inch (DPI) to be 200.

% pstoimg -antialias -density 200 geo_filt_990915-991020-sim_ODR_4rlks.int.ps  # this may take a while
# the program can now be viewed with gqview or xv
% xv geo_filt_990915-991020-sim_ODR_4rlks.int.png

Creating unwrapped LOS deformation plot:

Because the assumed final product of ROI_PAC is a deformation plot in Line-of-Site (LOS) length, this plot is considerably more straightforward to make.

Create an unwrapped deformation grd

% matlab  -nosplash -nojvm -nodesktop  << EOF
    addpath '/home/anewman/InSAR/matlab_common'
    unw2grd(1,'geo_990915-991020.unw','geo_990915-991020.unw.grd')
EOF

Create an unwrapped RADAR amplitude grd

% matlab  -nosplash -nojvm -nodesktop  << EOF
    addpath '/home/anewman/InSAR/matlab_common'
    unw2grd(0,'geo_990915-991020.unw','geo_990915-991020.amp.grd')
EOF

Now, with only minor modifications, you can change HMwrapped.gmt to a couple of new scripts for Amp and Phase plots. You can either do this on your own or copy my versions.
```
% cp ~anewman/MGM/HectorMine/int_990915_991020/HMamp.gmt .
% HMamp.gmt geo_990915-991020.amp
% cp ~anewman/MGM/HectorMine/int_990915_991020/HMunw.gmt .
% HMunw.gmt geo_990915-991020.unw
```
Example Images:
1. Radar Amplitude (990915-991020.amp)
2. Radar Interferogram: no correction (990915-991020_4rlks.int)
3. Radar Interferogram: orbit correction (flat_ODR_990915-991020_4rlks.int)
4. Radar Interferogram: SIMulated orbit and topographic corrections (990915-991020-sim_SIM_4rlks.int)
5. Radar Interferogram: orbit and topographic corrections (filt_990915-991020-sim_ODR_4rlks.int)
6. LOS Displacement (990915-991020.unw)

Course Home | anewmangatech.edu | Updated: Mon Apr 9 14:46:47 EDT 2012