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Question of Coregistering Sentinel-1 multi-look images (MLIs)
Added by Jack Chang almost 7 years ago
Hi Dr. Charles,
I am trying to coregister multiple Sentinel-1 GRD MLIs to a reference MLI using MLI_resamp_lt_all.
However there are some images have larger coregistration errors. Please see attached figure, reference image
is of 04/03/2016, image to be coregistered is of 03/05/2017 where there is an obvious range-direction shift (see
reference_20160403.vv.mli.bmp and original_20170305.vv.mli.bmp).
After coregistration, there is no obvious range-direction shift but there is an azimuth direction shift instead. (see
reference_20160403.vv.mli.bmp and coregistered_20170305.vv.mli.bmp)
I have tried several ways including changing patch size, using iterative refinement mode (rflag = 1), giving different
correlation threshold, using different number of parameters for offset model but none of them work. Is there any possible
way to deal with it? Or it is because images themselves have low coherence which inevitably deteriorate the performance
of coregistration?
On the other hand, is it possible to perform coregistration after geocoding?
Really appreciate your help :)
Jack Chang
Replies (2)
Question of Coregistering Sentinel-1 multi-look images (MLIs) - Added by Charles Werner almost 7 years ago
Hello,
Attached is the latest version of MLI_resamp_lt_all, that may be useful. I
suggest that after you run the script, you run each of the commands that it
performs and look at the results, specifically, when you run offset_pwrm to
measure the offset. You could also just have a single global offset that might
give the best result (offset_initm).
You will have to look at the data. You can also specify the place in the image
where you want to make an initial offset measurement, perhaps the mountains
below the lake is the best place. It could be that the changing water level in
the lake is dominating the offset determination, and causing the registration error.
Anyway, you can also use dis2pwr to get a visual idea of what the offset should
be, and offset_pwrm can have the options set to print out the offsets from each
patch on the screen (gamma_doc offset_pwrm). Anyway, good luck. You can solve this.
Charles
| MLI_resamp_lt_all (23.4 KB) MLI_resamp_lt_all |
RE: Question of Coregistering Sentinel-1 multi-look images (MLIs) - Added by Jack Chang almost 7 years ago
Hi Charles,
Thank you so much for your suggestion. I have solved this problem successfully!
Jack