I am tired to work with snaphu. Even on a Server PC (I am attaching the configuration). It aborts unwrapping after running for 3 days.
I have total of 21 Sentinel 1A tiles to process but I am late due to snaphu. I am trying with 4 tiles for the last 10-12 days but snaphu failed all time.
Let me know what I can do to complete my work!
can you please share
- a screenshot of the intererogram
- the size of a single S1 scene (rows / columns)
- the snaphu configurations (solver, tiles, overlap, processors)
- the amount of RAM of your system
CONFIG FOR SNAPHU
----------------------------------------------------------------
Created by SNAP software on: 02:18:48 26/11/2021
Command to call snaphu:
snaphu -f snaphu.conf Phase_ifg_VH_19Sep2021_07Sep2021.snaphu.img 67447
#########################
Unwrapping parameters
#########################
STATCOSTMODE DEFO
INITMETHOD MST
VERBOSE TRUE
###############
Input files
###############
CORRFILE coh_VH_19Sep2021_07Sep2021.snaphu.img
################
Output files
################
OUTFILE UnwPhase_ifg_VH_19Sep2021_07Sep2021.snaphu.img
#LOGFILE snaphu.log
################
File formats
################
INFILEFORMAT FLOAT_DATA
CORRFILEFORMAT FLOAT_DATA
OUTFILEFORMAT FLOAT_DATA
###############################
SAR and geometry parameters
###############################
TRANSMITMODE REPEATPASS
ORBITRADIUS 7072542.684
EARTHRADIUS 6373645.443
LAMBDA 0.0554658
BASELINE 20.102
BASELINEANGLE_RAD -1.529
NEARRANGE 799721.2704545
Slant range and azimuth pixel spacings
DR 2.3295621
DA 15.6147814
Single-look slant range and azimuth resolutions.
RANGERES 2653030.6018487
AZRES 81.9956992
The number of independent looks: approximately equal to the
real number of looks divided by the product of range and
azimuth resolutions, and multiplied by the product of the
single-look range and azimuth spacings. It is about 0.53
times the number of real looks for ERS data processed
without windowing.
NCORRLOOKS 23.8
################
Tile control
################
NTILEROW 10
NTILECOL 10
ROWOVRLP 200
COLOVRLP 200
NPROC 4
TILECOSTTHRESH 500
End of snaphu configuration file
Again another Unwrapping Failed:
hm, these are quite large rasters, do you really need the entire area? I wonder if persistent scatterer analysies are more suitable for such large extents. Also, multi-looking would be an option to reduce the raster size a bit. if none of this is feasible, please increase the number of rows and colums so that each tile is smaller. Currently, you have rasters with 13116 x 67447 pixels. If you have 10x10 tiles, each of them is still 1311 x 6744 pixels large. Maybe you can increase the tile size to 20 to avoid that unwrapping errors occur in single tiles.
Also, is there a reason why you calculated the interferograms from the VH polarization instead of VV? There is often less coherent scattering in the cross-pol channel.
@ABraun Yes I need the whole area and I have a total of 21 tiles like this. Which is suitable for DEM generation VH or VV?
I recommend co-polarization for any InSAR approach. Please see here: Effect of polarization on interferometric products - #4 by hriston_bg
Also, you should consider multi looking the interferogram. It is unlikely that unwrapping will produce the same results throughout all 21 images over such large areas.
What should be the par for multilooking in this case?
After TOPS deburst was applied to the interferogram. Helps to reduce the raster size and also prevents unwrapping errors in critical areas.