Error in unwrapped process

Everbody,I need some help.I look through Sentinel-1 Toolbox(Interferometry Tutorial) about Export to Snaphu.“Select TOPO mode for DEM generation.Select DEFO for deformation mapping”.So,when I do this step,I select TOPO and MCF in dialog box,but when I use snaphu.exe to unwrapped,the window show error
Besides,when I want to perform terrain phase correction,But I only find Topographic phase removal in snap box.:sweat:

what error is displayed?
Topographic phase removal is the same as terrain phase correction, the manual is based on a previous version of SNAP where some modules were slightly different.

Oh,if I use insar technology to generate dem, do I have to perform terrain phase correction? Terrain phase correction should be an indispensable step when use insar technology.But i look through the forum some scholars said that there isn’t need to be terrain phase correction in generation dem.Now,I am now a bit confused.

the window show is
Did I understand the error in the manual “Select TOPO mode for DEM generation”?:joy:

if you want to create a DEM

  1. do not apply topographic phase correction (maybe this caused the error)
  2. use TOPO instead of DEFO

OK,I select TOPO,but unwrapped phase can’t progess,the commend window show the upper question,if i select DEFO ,the unwrapped phase step could progess

DEFO is only for DInSAR applications so this won’t help you I guess.

Have you tried running it in another folder without special charactes, for example C:\Temp\

What exact steps did you untertake with your data?

Thanks ,I just try do snaphu export to C:\Temp,then I select TOPO and MCF in dialog box,but it still show the same problem.:sob:Is it I installed the unwrapping plugin error?I installed it according to the installation instructions you had shared with me before.

Process steps is subset>coregisteration>interferogram>topographic phase removal(I don’t do this step) >filter>multilooking>band math>unwrapped>phase to height>terrain correction.

Besides,I would also like to know how to choose “SMOOTH” and “NOSTATOCSTS”,as I use INSAR technology to generate DEM need to choose TOPO.

what band math did you apply before unwrapping?

I use" interfered_Stack_ifg_flt.dim"

I would skip that part and directly export interfered_stack_ifg_flt_ML for unwrapping

Thanks,I just do “snaphu export”,I only select"DEFO"and"SMOOTH" ,the unwrapped could progress,once select"TOPO",the unwrpped will failured.
Have you ever encountered the same problem?I don’t know how to deal with it.Pray for help

I never heard of such a behaviour, sorry.

The only thing I can offer is the standard workflow which should work for most cases for DEM generation:

  1. coregistration
  2. interferogram formation
  3. phase filtering (optional)
  4. snaphu export
  5. unwrapping in snaphu (TOPO)
  6. snaphu import
  7. phase to elevation
  8. terrain correction

Please try these steps in exactly this order.

I am very happy you have been helping me to answer my question, thank you.

What tile cost threshold did you use? You can try with a threshold around 10.000.

I use 500 tile cost threshold before.I try with a threshold around 10,but it still failured.

You should try 10000, sorry for the misunderstanding.

Oh,I also try 10000,but still can’t progress. This problem shouldn’t related to the software or data.

if DEFO worked, did you import it in SNAP again and look if it is okay?

Because TOPO isn’t work,so I export all through the “DEFO” generated DEM.then import it in snap,but the resulting DEM accuracy is not high.

In addition, the accuracy of the generated DEM can be expressed by other means of size, I can only view the two points on the map elevation value.Is it possible to display the maximum and minimum values of the elevation difference between the two images?

yes in the band maths operator. Right-click on a band, select band math, and subtract the first from the second. This creates a third raster which displays their difference.