Hello, My Friends …
I try to Generated DEM with Sentinel1 data.
After I read most of the articles here about generated DEM, I download more than 4 pair for Sentinel 1 with different dates and I choose the best pair to show the result here …
2 images of Sentinel-1 with temporal baseline 12 days and perp… baseline 172m…
my coherence very good with mean 0.7 as shows here
My result DEM here
another DEM results from 2 pair with temporal baseline 6 days and perp… baseline 181m but means coherence about .043
My question …
- Why there is a straight line in Generated DEM and why they are the difference with reference DEM more than 125 m.
- I show some Sentinel-1 data especially Sentinel-1B with 10 bursts??
If there is any advice concerning the subject??
Ammar, have you perfromed the Deburst operator?
Dear Tomcator ,thanks for your replay.
Of course I performed Deburst step and all other steps without any problem …
But I think I found the source error , which is I used reference DEM with UTM coordinate and now I try with geographic coordinate and I get best results as shown below with one line in red box…
My question , what the best parameter for snaphu export?? and how will be the effect on the result for my phase before snaphu export without these line as shown below?
during the unwrapping, these patterns are sometimes introduced.
Try to reduce the number of tiles and add a considerable overlap instead. An explanation is given here: SNAPHU parameters
So you can try to increase the tile overlap firrst and reduce the number of tiles a bit as well. If this doesn’t give better results, try SMOOTH instead of TOPO. Lastly you compare MST and MCF for the unwrapping.
Dear ABraun, thank you for your replay and soeey for my late replay but all time yesterday I try with all parameters of snaphu export since I know my problem with these parameters because of my interferogram result with no phase jumping or any unnormal line. Finally, I got the excellent unwrapped image with the number of tiles 1 for rows and columns in my image of 3 bursts default another parameters as shown below
22.bmp (1.7 MB)
One case I get a good unwrapped image with DEFO option with default other parameters as shown below
25.bmp (1.7 MB)
these images for to scene of S-1B.
My question …what best method to mosaic them images from two scenes? I used SAR mosaic images after all processing and it has done but with the different legend or don’t read elevation as shown in below image
another way I made moseic after unwrapping step and the result very good as shown below
But the mosaic image can’t work in Phase to Elevation step because it is projected?
Instead of mosaic you might want to try the S1 Slice Assembly operator.
After any step i can use Slice Assembly ? after interferogram or Deburst ??
I haven’t tried but I would test it after the unwrapping. If that produces harsh boundaries, apply it after the interferogram generation.
It is important to check the unwrapped interferogram (your screenshot shows the original one).
I have to unwrapped with overlapping area as shown below
I try after Unwrapping but there is error message (( Slice Assembly)java.lang.nullpointerexception)
I see slice assembly need to polarisation??
I don’t think it is related to polarization (as long as both interferograms are based on VV)
Maybe someone has an idea?
I know both interferogram based on one polarization but as you see in image below
It same this option found in deburst and merge step.
I try Slice Assenbly after interferogram but also with error message as below
I make mosaic out of SNAP after all processing and export to Tiff and the result as below
I found the solution …
A Slice Assembly work before interferogram that means after Coregistration of two subswath belong to different scens then make slice assembly as shown in below
After that I made interferogram as shown without any problem
After made Deburst, multilooking and Goldstain Phase Filtring
Slice assembly could be done, after TOPSAR split , Please take a look at the following similar post,
Source of the post
Dear Falah …
Thank you so much