Radiometric Terrain Flattening - Hot solve low DEM resolution?

[amithaldar87]

Hi,

I am stuck again in this step do you have any solution for that?? I am trying rectify image this error is coming at the step Radiometric Terrain Flattening.

[ABraun]

Uncheck the re-grid method, then run the terrain flattening.

[amithaldar87]

@ABraun Thanks again for rescuing me again.

[ABraun]

glad it helped, but the solution was already given here

[Terrain-Flattening] The DEM resolution is lower than that of the source image

Use of SRTM 1arcsec DEM with Sentinel-1 GRDH images was possible with SNAP 3.0, and results were acceptable. SNAP/S1TBX 5.0.x now reports: The DEM resolution is lower than that of the source image. Please multilook the source image or use higher resolution DEM (e.g. SRTM 1Sec HGT) to make sure the DEM resolution is higher than that of the source image. A possible workaround may be to up sample the DEM to 0.5 arcsec. However, we may revert to SNAP 3.0 since Terrain-Flattening of Sentinel-1 GRD…

Effect of Multilooking on Terrain Flattening

You can skip the multi looking by changing the re-grid option in the terrain flattening module. A comparison of the result with and without multi looking would be interesting.

Terrain flattening co-registered images

Disable the re-grid option and you can flatten without multi-looking.

[marifo]

What is the re-grid option exactly. How the uncheck or check the “re-grid method” may affect our results I am processing Sentinel 1 data to study some evolution in a lake and for some I could use terrain flattening with checked re-grid box and for some I had to uncheck them otherwise it gives an error. So my quesiton is that becaause I want to study multi-temporal images does it matter if the “re-grid method” is checked for some and not for others. And how does it effect my results. Any suggestion?
Thanks

[cfgobel]

I’m having the same problem trying TF in a COSMO-SkyMed image. I only succeed when performing multi-look before TF and uncheck the “re-grid” option. I still don’t understand what it exactly does. The help document is not up to date so could not figured it out.
Also, only work with DEM in UTM projection. A finer DEM resolution um stereographic projection produce a blank image as result.