Problem in DEM generation

hi all,
I have unwrapped the interferogram image the whole process was done using SNAPHU export option. the process run more than 1hr. but when i try to generate DEM it shows that no unwrapped phase was found. so how can i solve the problem? can anybody please help me out.

I had the same problem.
I’m following this topic.

can you able to solve the problem? if yes then please tell me the entire process for DEM generation.

If I solve it, I tell you.

did you import the correct product with the SNAPHU import?
Is the unwrapped phase among the imported bands?


first i snaphu export tool.after run this process i got the following files
now i cant able to understand what should be the input for snaphu import option? and how can i run the import process.

the import should be the Goldstein filtered product (or a saved subset from them). I dont know which version are you using, but for me it was only working with s1tbx 1.1.1… Snap gived me always an error.

i am using Snap sentinel toolbox 2.0.2. i cant understand what should be the input for snaphu import. if anyone know this then please help me for solve the problem.its urgent.

Hi Priyankaroy,
I have the same problem with snaphu export . I did the Goldstein phase filtering, and then i try to export with snaphu (i’am interested in DEM, i use the TOPO and MCF option). Snap don’t give me an error and it generate same files as you:index (128.4 KB)

A first step to understand our problem: if you check the snaphu.conf file, snaphu export command should return a file : “UnwPhase… .img” but we have just the .hdr file (header) and the .img still missing. It is necessary to get this .img to import with snaphu…

I share with you if i can fix the problem
Best regards

The unwrapped phase image will be created after running snaphu

Thanks for your attention.

Telle me if i understand:

I run snaphu export, it generate coherence (header and img), Phase (header and img), snaphu.conf, Unwrapped phase (only header).
And then i d’ont run snaphu import in snap but i launch VM linux (i am a windows user), and i run snaphu in command line to generate the Unwrapped image file .
Next i import this new file in SNAP to follow my dem generation process ?

Yes, run the snaphu command found in the snaphu.conf. It will produce the unwrapped image. Then use snaphu import within SNAP to put together the metadata from the wrapped phase product with the unwrapped phase data from snaphu and then run the dem generation operator to get heights referenced to some points on an existing dem.

weather snaphu can be installed and run through cygwin?

after snaphu import process may i run phase to height conversion for DEM generation?? and i want to open it through Arcgis or ERDAS. may i save it as geotiff product?

yes,maybe you should look throughERS ETNA DEM Generation

Hi everybody,

I would like to ask about DEM Generation step.
Basically using SNAP Desktop, I can generate a DEM by using the Phase to Elevation (SNAPHU Unwrapped Phase) from TanDEM-X bistatic dataset. Anyhow about the geometric accuracy, it is still in the range of 10 m (NSSDA 95% level of confidence referring to the accurate Checkpoint from GNSS measurements). If I use my own algorithm to adjust the baseline, height reference and phase offset estimation based on GCP data, I can improve the geometric accuracy up to 3-5 meter accuracy. It looks like the Range Doppler Terrain Correction (Geocoding) ended up only in the level of accuracy of SRTM 1 Arc Second (5-6 m accuracy) as I used it. If I attach the GCP geocoding, the geometric accuracy is not even better. I pointed also that the SNAP 5.0 doesn’t give the better results for DEM Generation. Do you have any information concerning SNAP geocoding algorithm or any further suggestion to improve the geometric accuracy.

Best regards,