GAMMA Questions

!!

Hello,
Here is the link to an example of Sentinel-1 ice tracking with Gamma software

https://1drv.ms/u/s!Ag_xahLucCVfiWjAVK_ef9_KhLFq?e=hJoLdO

Best regards,
Charles Werner

Thanks for your reply. I have refered the Sentnel-1 ice tracking with GAMMA. But the demo is located Greenland and the co-register of image pairs is using S1_coreg_TOPS with dem.

Here I want to use precise orbit to co-register. And I didn't know why use second offset feild and using offset_pwr_tracking2. The function could improve the quality of velocity field.
And demo script 3B section , it look like without co-register and use directly SLC_interp_S1_TOPS function.

############################################################## ##############################################################

1. 3B) Alternatively a co-registration simply based on the orbit information,
2. using a constant height, without any refinement can be applied. Often
3. this may be sufficient for a subsequent offset tracking

/bin/cp inputs/* .

1. 20141022: generate mosaic, then generate MLI from this mosaic and visualize
2. using a bmp rasterfile
   echo "20141022.IW2.slc 20141022.IW2.slc.par 20141022.IW2.slc.TOPS_par" > 20141022.SLC_tab
   echo "20141022.IW3.slc 20141022.IW3.slc.par 20141022.IW3.slc.TOPS_par" >> 20141022.SLC_tab
   SLC_mosaic_S1_TOPS 20141022.SLC_tab 20141022.slc 20141022.slc.par 10 2
   multi_look 20141022.slc 20141022.slc.par 20141022.slc.mli 20141022.slc.mli.par 10 2
   raspwr 20141022.slc.mli 4752 1 0 1 1 1. .35 1 20141022.slc.mli.bmp
   eog 20141022.slc.mli.bmp &

1. -->
2. 20141022.slc 20141022.slc.par
3. 20141022.slc.mli 20141022.slc.mli.par

1. 20141103: generate mosaic, then generate MLI from this mosaic and visualize
   echo "20141103.IW2.slc 20141103.IW2.slc.par 20141103.IW2.slc.TOPS_par" > 20141103.SLC_tab
   echo "20141103.IW3.slc 20141103.IW3.slc.par 20141103.IW3.slc.TOPS_par" >> 20141103.SLC_tab
   SLC_mosaic_S1_TOPS 20141103.SLC_tab 20141103.slc 20141103.slc.par 10 2
   multi_look 20141103.slc 20141103.slc.par 20141103.slc.mli 20141103.slc.mli.par 10 2
   raspwr 20141103.slc.mli 4752 1 0 1 1 1. .35 1 20141103.slc.mli.bmp
   eog 20141103.slc.mli.bmp &

/bin/rm 20141022_20141103.off
create_offset 20141022.slc.par 20141103.slc.par 20141022_20141103.off 1 10 2 0

echo "20141103.IW2.rslc 20141103.IW2.rslc.par 20141103.IW2.rslc.TOPS_par" > 20141103.RSLC_tab
echo "20141103.IW3.rslc 20141103.IW3.rslc.par 20141103.IW3.rslc.TOPS_par" >> 20141103.RSLC_tab

rdc_trans 20141022.slc.mli.par 0.1 20141103.slc.mli.par 20141022_20141103.lt
SLC_interp_S1_TOPS 20141103.SLC_tab 20141103.slc.par 20141022.SLC_tab 20141022.slc.par 20141022_20141103.off 20141103.RSLC_tab 20141103.rslc 20141103.rslc.par

############################################################## ##############################################################

1. 4B) offset tracking
2. here no oversampling is used in the offset estimation; accordingly it is not necessary to deramped the IWS SLC

1. prepare MLI in the geometry of the offset estimates
   multi_look 20141022.slc 20141022.slc.par 20141022.mli5 20141022.mli5.par 50 10 0 -
   raspwr 20141022.mli5 950 1 0 1 1 1. .2 1 20141022.mli5.bmp
   eog 20141022.mli5.bmp

1. estimate offset field: window size (256x64) step (50,10)
   offset_pwr_tracking 20141022.slc 20141103.rslc 20141022.slc.par 20141103.rslc.par 20141022_20141103.off 20141022_20141103.offsB 20141022_20141103.ccpB 256 64 - 1 0.01 50 10 - - - - 4 0 0

1. offsets have been stored as complex numbers, with the real part containing range offsets and the imaginary part containing azimuth offsets
   cpx_to_real 20141022_20141103.offsB 20141022_20141103.offsB.real 950 0
   cpx_to_real 20141022_20141103.offsB 20141022_20141103.offsB.imag 950 1

dishgt 20141022_20141103.offsB.real 20141022.mli5 950 1 1 0 50. 1. .35
dishgt 20141022_20141103.offsB.real 20141022_20141103.ccpB 950 1 1 0 30. 1. .35

dishgt 20141022_20141103.offsB.imag 20141022.mli5 950 1 1 0 50. 1. .35
dishgt 20141022_20141103.offsB.imag 20141022_20141103.ccpB 950 1 1 0 30. 1. .35

rashgt 20141022_20141103.offsB.real 20141022.mli5 950 1 1 0 1 1 50. 1. .35 1 20141022_20141103.offsB.real.bmp
rashgt 20141022_20141103.offsB.imag 20141022.mli5 950 1 1 0 1 1 50. 1. .35 1 20141022_20141103.offsB.imag.bmp
dis2ras 20141022_20141103.offsB.real.bmp 20141022_20141103.offsB.imag.bmp &

1. --> there is a significant non-zero overall offset related to not co-registering
2. the slave slc correctly to the reference slc (assumed constant height differs
3. from real height because of geoid height and topography)

1. To subtract this overall offset we use offset_fit and offset_tracking

why it didn't subtract the offset field trend?++**

1. we also consider linear trends and use therefore npoly=3
   offset_fit 20141022_20141103.offsB 20141022_20141103.ccpB 20141022_20141103.off coffs - 0.1 3

1. final solution: 77033 offset estimates accepted out of 415150 samples
2. final range offset poly. coeff.: 5.47248 6.86100e-05 -1.80798e-05
3. final range offset poly. coeff. errors: 2.44556e-03 8.34239e-08 4.45071e-07
4. final azimuth offset poly. coeff.: -4.02070 1.23002e-06 -2.14985e-06
5. final azimuth offset poly. coeff. errors: 1.58632e-03 5.41132e-08 2.88697e-07
6. final model fit std. dev. (samples) range: 0.0615 azimuth: 0.0399

1. then we subtract this trend and convert the values to meters in ground range and azimuth
   offset_tracking 20141022_20141103.offsB 20141022_20141103.ccpB 20141022.slc.par 20141022_20141103.off 20141022_20141103.disp_mapB - 2 0.05 1
   cpx_to_real 20141022_20141103.disp_mapB 20141022_20141103.disp_mapB.real 950 0
   cpx_to_real 20141022_20141103.disp_mapB 20141022_20141103.disp_mapB.imag 950 1
   cpx_to_real 20141022_20141103.disp_mapB 20141022_20141103.disp_mapB.mag 950 3

dishgt 20141022_20141103.disp_mapB.real 20141022.mli5 950 1 1 0 250. 1. .35
dishgt 20141022_20141103.disp_mapB.real 20141022_20141103.ccpB 950 1 1 0 250. 1. .35

dishgt 20141022_20141103.disp_mapB.imag 20141022.mli5 950 1 1 0 250. 1. .35
dishgt 20141022_20141103.disp_mapB.imag 20141022_20141103.ccpB 950 1 1 0 250. 1. .35

dishgt 20141022_20141103.disp_mapB.mag 20141022.mli5 950 1 1 0 250. 1. .35
dishgt 20141022_20141103.disp_mapB.mag 20141022_20141103.ccpB 950 1 1 0 250. 1. .35

rashgt 20141022_20141103.disp_mapB.real 20141022_20141103.ccpB 950 1 1 0 1 1 250. 1. .35 1 20141022_20141103.disp_mapB.real.bmp
rashgt 20141022_20141103.disp_mapB.imag 20141022_20141103.ccpB 950 1 1 0 1 1 250. 1. .35 1 20141022_20141103.disp_mapB.imag.bmp
rashgt 20141022_20141103.disp_mapB.mag 20141022_20141103.ccpB 950 1 1 0 1 1 250. 1. .35 1 20141022_20141103.disp_mapB.mag.bmp

Hello,

offset_pwr_tracking2 has the ability to enter an initial offset map, very useful
when working with fast moving glaciers. The initial offset map is  (obtained at
lower resolution using large patches),
Then use that map with offset_pwr_tracking2 to then measure offsets with smaller
patches, even if the total displacement is large.

Measuring offsets do not have to be as precise as the coregistration of
Sentinel-1 patches for interferometry.
That is why there is not need for the double-difference interferometry and you
can just use the S1_interp_S1_TOPS program directly.

You could also use the script S1_coreg_TOPS_no_refinement and enter a constant
value for the height map instead of a DEM file name.

Best regards,

charles

Thanks for your suggestion.
My veocity results have trend due to coregistration or other reason? the velocity values during 12 days is reached to 64m but in reality, the velocity is only 30m. And our results in stable region is 30m.If I subtract the value stable region, we can get the nice results.
Which function I need to use change offset field?
The attachment is my ice velocity field file.!!

To subtract this overall offset we use offset_fit and offset_tracking

we also consider linear trends and use therefore npoly=3
*offset_fit 20141022_20141103.offsB 20141022_20141103.ccpB 20141022_20141103.off coffs - 0.1 3 *
final solution: 77033 offset estimates accepted out of 415150 samples
final range offset poly. coeff.: 5.47248 6.86100e-05 -1.80798e-05
final range offset poly. coeff. errors: 2.44556e-03 8.34239e-08 4.45071e-07
final azimuth offset poly. coeff.: -4.02070 1.23002e-06 -2.14985e-06
final azimuth offset poly. coeff. errors: 1.58632e-03 5.41132e-08 2.88697e-07
final model fit std. dev. (samples) range: 0.0615 azimuth: 0.0399
then we subtract this trend and convert the values to meters in ground range and azimuth

offset_tracking 20141022_20141103.offsB 20141022_20141103.ccpB 20141022.slc.par 20141022_20141103.off 20141022_20141103.disp_mapB - 2 0.05 1

SLC_interp_Sq_TOPS function looks like no coregistration and just resample into RSLC