I tested the different coregistrations (DEM-assisted and normal) and inside the coregistration I have tested with and without the apply fine registration for SLCs but I obtained the same. For the other parameters do you have some suggestions ?
Thanks
What are the dates of your images?
Here are some tutorials:
29/04/1995
09/07/1995
over the golf of Corinth
Thanks for the tutorial but actually I am used to work with sentinel
I guess the reason is either better coregistration or less decorrelation.
What can I modify ?
Use the shortest possible repeat-cycle and images from a dry period so the situation is more stable. If there’s any ERS-1/2 Tandem data with 1-day temporal baseline that would have much higher coherence than the standard 35-days for ERS.
A new tutorial was published - also dealing with how to find suitable ERS image pairs: InSAR Displacement mapping with ERS data
Hello to all,
I’m experiencing a similar issue,
I’m studying the 2001 Buhji earthquake and I want to generate DEM from ERS data.
I fail in the “standard” coregistration processing. In particular the slave image is always empty (I followed the NEST tutorial downlodable in this link: https://earth.esa.int/web/nest/news/-/article/dem-generation-with-nest). Here a screen of the empty image:
The perpendicular baseline of 2508 m seems strange. Maybe something went wrong during the application of orbit files (similarly reported here).
Can you please test the InSAR stack overview also for the two input products before application of the orbit files?
The tutorial is rather old. Maybe you want to compare these two as well.
Same bperp even not applying the orbit correction
Is your data located near the international dateline?
If the images are from the same track they should not have such a large perpendicular baseline.
Nope… the images are from the UTC +5:30 hours (Gujarat NW India).
I will try with another couple of images but few month younger…
yes, please check if all pairs have these odd baselines or if it is maybe one faulty metadataset which causes this large value.
Still, if both images are acquired from the same track, coregistration should be possible. Have you tried DEM-based coregistration with cross-correlation?
Your second image is after ERS-2 went gyro-less and orbit control became worse than before, explaining the large baseline and close to 500Hz difference in doppler. Try to find a more compatible pair.
Right… I keep forgetting the zero gyro phase.
Thank you mengdahl!
So I will use images acquired after June 2001 which is a bit problematic for me because I want to study the 2001 Bhuj earthquake which happened in February…
I will try with new “younger” couple of images hoping for better correlation!
If you are lucky you may find a pair with compatible doppler and short baseline also in the worse controlled mission phases. Does the current download-interface support InSAR-search where you can search for compatible dopplers and baselines?
Yes it support InSAR-search, but even using such tool and selecting 2001 images (20010719 and 20010823) I cannot obtain interferograms characterized by good correlation values…
I will persist and try new younger images!
