As ABraun said mentioned, if your coherence is low, no fringes are formed, hence, you have just random phase. By looking at your SAR image, it looks like the coherence is low apart from a few areas in your image. The quality of the interferogram is heavily depends on the coherence.
I guess that what you are trying to do is to estimate movement/subsidence on the ground ? if yes, then areas with random phase (low coherence areas) cannot be used for estimating movement or subsidence. You may need to look at your coherence map.
In terms of the second image, it looks like the coherence is high, hence, the nice fringes.
I think coregistration also plays a major role in the resulting quality of the interferogram. Besides that, Multi-looking, filtering or the quality of the DEM could have differed in the cited study which all increase or decrease quality of your fringes.
@mauleon.fb I can’t imagine the coherence being that bad with just 6 days between passes. Did you use the same subswaths in each scene? Do they sit on top of each other well, or is one subswath different from the other? Did you use S1 TOPS Coregistration? Did you check the modeled coherence after coregistration? (Radar > Interferometric > InSAR Stack Ov erview) Add your files and run the overview. The modeled coherence should be as close to 1 (or 100%) as possible.
Are you sure that the interferogram you are trying to replicate was processed using the same exact datasets? Was ESA SNAP used for this?
Yes, highly recommend reaching out to the authors directly to see where you are falling short. I am eager to see what was done to accomplish the results shown in the paper.
Yes I would be eager and excited as well to know what was done on the process to achieve the results shown on the paper…and it would help as well to note in future processing of insar
@dsmilo where in the process should subset be done if using TOPSAR data? i think it can be done after interferogram formation and debursting am i right?
@ABraun well yours still show bigger fringes than mine. Mine looks grainy rainbow coloured in all images
This should be your first step. Then coregister…ect…
If you perform a subset after coregistration or even interferogram, you are essentially clipping or cropping the image to make it smaller, not really performing a true subset.
However,after coregistration(Radar>Coregistration >S1 TOPS Coregistration with ESD),it has stacked into a single file,how can I run stack overview?Thanks
If you have already coregistered them, you can load the InSAR Stack tool (under View > Tool Windows > Radar > InSAR Stack)
The single tabs will show you the baseline information as well.
Thanks a lot ,here are more question:what’s the differnece between the menu of coregistaton>Stack Tools>Create Stack and Interferometric > InSAR Stack Overview ,which is both sub-menu of Radar in SNAP7.0?
so late for thanks to you,now I’m interesting in PSI of how to pickup the unusuall shift trend of PS candidates and ingoring normal PS candidates ,then visualize them,Could you give me more suggestions ?