SNAPHU Unwrapping


#101

19
Hi
I’m agree, I chose the DEFO parameter.
Regards,


#102

Hi
If this problem is occured during coregistration, It should appeared in wrap interfergram too. but the interferogram didnt have this behaviour. Also I saw many vertcal and horizental tiles . What shoul I do?


#103

@amighpey: That depends on what you want to achieve in your study. Do you want to detect subsidence or generate a DEM?


#104

I want to detect the subsidence


#105

I this case DEFO is the correct parameter. Maybe you try again with the MCF parameter instead of MST


#106

Hi,

I think i it is not appear always in the wrapped phase, please take a look to this article “SENTINEL-1 RESULTS: SBAS-DINSAR PROCESSING CHAIN
DEVELOPMENTS AND LAND SUBSIDENCE ANALYSIS”


#107

Hi
Changing the initial method (MST or MCF) has no effect on the result. the discontinuity is remained.


#108

hmm

you could also try the -s option with promotes smooth outputs:

snaphu -s infile length

-d additionally uses deformation mode costs.


#109

I try -s and -d option, but it deteriorated the result!


#110

hmm, did you perform topographic phase removal on the interferogram?

Did you apply a Golstein filter before unwrapping?


#111

Hi
I read the paper. The authors propose the SD method to improve the accuracy of the coregistration. I think S1tbx apply this method. Am I right? Do you mean I should applied the SD method by myself?
Moreover, I have this problem in the area which located on one burst. What should I do?


#112

yes, I perform all this staged.


#113

it seems that there is a jump in the values at the border where the TOPS beams were mosaiced

did you perform the S1 TOPS coregistration or have you debursted both images seperately and then made a stack?


#114

no, Please take a look at my picture:

Here is my stages:

Step 1 ) S-1 Tops coregistration
Step 2 Interferogram formation
Step 3 ) S-1 Tops Deburst
Step 4 ) S-1 Tops merge
Step 5) Topographic phase removal
Step 6) Goldstein phase filtering
Step 7 ) Multilooking
Step 8 )Snaphu-export and unwarping by snaphu


#115

As you see at the picture the jumps also are away from the border.


#116

Why are you debursting and merging the data again after the interferogram formation? This is achieved by the S1 TOPS coregistration already. I guess you could skip steps 3 and 4.


#117

I procese the data based on the manual of the software. S1 top coregistraion only process one band of data, IW1 or IW2 or IW3. the out put is the phase of that band of 2 images which are debursted. I first deburst these phase and then merge IW1 and IW2 bands.


#118

II procese the data based on the manual of the software. S1 top coregistraion only process one band of data, IW1 or IW2 or IW3. the out put is the phase of that band of 2 images which are bursted. I first deburst these phase and then merge IW1 and IW2 bands.


#119

you are right - sorry. TOPS coregistration only performs one swath and the result still has demarcations so debursting is needed.

I’m not sure, but the jumps must come from debursting and merging.
I found some similar patterns here:
http://seom.esa.int/fringe2015/files/presentation322.pdf (slide 29 and 30)

Maybe someone can clarify - is S1 InSAR only possible with single TOPS swaths?


#120

Hi,

What Id like to mention is that the S1A needs cor. accuracy 0.1 in azimuth and 0.8 in range to avoid the jumping phase, especially if the study area is located in two or more than two bursts, that also what I personally phased in my PhD using the ERS-1\2 and ENVISAT,

You could find more details about this in

2.6.1.1 image co-registration

in the following reference

and

“Although the processing of the IWS (TOPS) mode requires additional processing steps and the coregistration has to be performed with the precision of 0.001 pixel (in the azimuth direction), if an area within one burst is processed, such a precise coregistration is not necessary.”

You could find more details in the following reference

(SENTINEL-1 INSAR PROCESSING OF CORNER REFLECTOR INFORMATION IN THE NORTHERN-BOHEMIAN COAL BASIN)


Difference between Phase calculated using Band Math option and Multilook operation
SAR Coherence over Himalayan glaciers - which co registration method to choose?