Dem-elevation

[falahfakhri]

@Ammar

I think this unwrapping error and I tried more time to overcome this problem, try to repeat the unwrapping process with different tile and if your images size with about 5000 pixels you can unwrap with 1 tile in rows and columns.

Dear Amman, thanks for giving your advice, this issue is solved at the time, actually, it was part of lecture in the Agricultural Dep. Un. of Helsinki.

But coming back to your questions,

@Ammar

I tried to generate DEM from Sentinel 1 different images, but my best images with coherence more than 0.7 but all my results with elevation less than my study area elevation about 100 to more than 200 m.

I have explained the differences of elevations in created DEM Compering to SRTM and ground truth, in the following post, please take a look,

Source of the post

@Ammar

You can see also unwrapping error.

This could be phase jump,

Did you apply Enhanced Spectral Diversity (ESD)?

Please take a look at the following post,

Source of the post

Also check up the corr. accuracy, because the low corr. accuracy could be a reason of phase jump,

Source of the post

To check the corr. error or accuracy in SNAP, use InSAR Stack tool

It’s also mentioned in this post, coregistration error,

Source of the post

It’s worth looking at this presentation as well, Precise coregistration of Sentinel-1A TOPS data
Source: https://files.scec.org/s3fs-public/0129_1400_1530_Fattahi.pdf