Hi, i have been trying to study a land subsidence case. While trying to unwrap the wrapped dinsar image the process always gets aborted after unwrapping 3 columns and shows this error message “snaphu v2.0.4
27 parameters input from file snaphu.conf (84 lines total)
Logging run-time parameters to file snaphu.log
Creating temporary directory snaphu_tiles_1413
Unwrapping tile at row 0, column 0 (pid 1414)
Unwrapping tile at row 0, column 1 (pid 1415)
Unwrapping tile at row 0, column 2 (pid 1416)
Unwrapping tile at row 0, column 3 (pid 1417)
Unexpected or abnormal exit of child process 1414
Abort
Exiting with status 1 on signal 15
Process exited with value 1
Finished tool execution in 4 seconds
Process exited with value 1
Finished tool execution in 4 seconds”
i have been trying really hard to find a solution for this. If anyone could help.
Can you please show a screenshot of your interferogram?
This is the dinsar generated after goldstein phase filtering
This is the overall steps that i followed
I am receiving this error message while trying to unwrap using the Snaphu-unwrapping tool from Radar>Interferometric>Unwrapping
the interferogram looks good. So maybe you can cange some parameters (more/less tiles, MCS/MST solver) and test again.
I have tried changing solver from MCF to MST and also tweaked the other parameters, but still the same error message is repeating.
For this screenshot i used MST with no. of tiles and rows:20, overlap:400
please try with only 6 rows and colums
Thank you so much for your suggestion, but still my process is getting aborted with 6 rows and columns also.
It could be worth turning to mask low coherence areas before unwrapping: Filter out low coherence pixels before phase unwrapping
Which file do i need to use as an input for phase unwrapping? Is it the .img phase file from the snaphu export folder or the normal dinsar file created after goldsteinphasefiltering? I performed the masking on the normal dinsar output file, but if that file is not to be used for phase unwrapping, it makes no difference whether i mask it or not.
You apply the masking of low coherence areas in the Phase band before unwrapping (don’t forget to save it).
Then you apply the snaphu export which prepares the snaphu.conf file which contains all relevant parameters (including input and output files)
Then you run the actual unwrapping process based on this file. So actually, there is no need to select a file. The safest way to have everything done correctly is to run it via the command line.
Thank you so much ABraun. It finally worked for me. Just one more question. The product generated from phase to displacement gives us the amount of upliftment and subsidence. Since i am studying landslides movement, i am considering the subsidence information as the movement caused by the landslide. So am i correct in assuming that?
Good job. The unwrapped interferogram indicates the relative motion between both images towards (or away from) the sensor. So it all depends on look detection and angle as well, but often these movements fall together. It is important that you received coherent signals at the landslide (high coherence) so that the phase contains valid information about the changes.
Ok, thank you so much. Hoping to learn more from you in the future.
Hi there,
I am actually trying to unwrap the interferogram and have tried every possible combination of rows and column overlap and number of tiles, but still my unwrapped phase shows some random tiling pattern, and I understand that it might be due to noise or decorrelated phase information, but is there any way to blend this pattern?
These are SNAPHU tiles. You might reduce the tiles numbers and check connected components SNAPHU output file for the unwrapping quality estimation. You can try different SNAPHU tiling parameters in this interactive Google Colab Jupyter notebook: Google Colab
I tried reducing the number of tiles to even 1, but still these random patterns are persistent.
It looks as topographic phase so you probably do not use DEM. If you use it is incorrect. Otherwise, you still have multiple SNAPHU tiles.
But if I subtract topographic phase, so will I be able to achieve a DEM from the interferometric phase?
I am getting this error while doing snaphu unwrapping although after goldstein filtering i masked out area with low coherence
parameters input from file snaphu.conf (84 lines total)
WARNING: Tile overlap is small (may give bad results)
Logging run-time parameters to file snaphu.log
Creating temporary directory snaphu_tiles_1662
Unwrapping tile at row 0, column 0 (pid 1663)
Unwrapping tile at row 0, column 1 (pid 1664)
Unwrapping tile at row 0, column 2 (pid 1665)
Unwrapping tile at row 0, column 3 (pid 1666)
Unexpected or abnormal exit of child process 1663
Abort
Exiting with status 1 on signal 15
Process exited with value 1
Finished tool execution in 4 seconds
Process exited with value 1
Finished tool execution in 4 seconds