I used the following graph as first step of InSAR but whichever DEM I used (except for SRTM which does not cover my study area), including external DEM, the phase band in the output keep showing up with both minimum and maximum value as zero (phase band is all purple). Coherence also show minimum as 0.0 and maximum as 4.9E-324. I am not sure why this has been happening. Has anyone faced this kind of problem before or know how to tackle this? Please let me know.
Is your version of SNAP up to date?
Please check in the menu > Help > Check for updates
Not sure if the error comes from there. It could also be problem s during coregistration. But please be sure you check @ABraun comments before.
Info about the processing log could help to identify your problem.
@mdelgado @ABraun I updated SNAP, and the results were still the same. I even tried doing that using two different pairs this time, but no luck.
@mdelgado What exactly do you mean by problem during coregistration? I applied the same methods I did for my previous studies, but I don’t understand why it’s not working.
You can check with an RGB image as described in this post: Fault marking by InSAR Data and difference between SLC_1SSV and SLC_1SDV?
If both images are aligned well, the RGB should be predominantly yellow. If not, the coregistration failed and therefore, no interferogram could be computed.
Error in the coregistration may not depend on the utilisation of the same graph. For example, any error on third party dependencies may affect your processing, such as:
- Availability of orbits or server which contains the orbits to be downloaded
- Availability of the DEM employed on the Back-geocoding or the server that contains it.
- Not correspondence on master/slave in terms of spatial coverage or different parameters employed during the splitting…
Additional problems with RAM, JVM, HDD can also affect it.
Still, I guess that you have checked that.
Let us know which data you have used, so we can try something. Otherwise without looking at logs or anything else, I think you understand that it may be difficult to put some light on your problem