Problem with terrain flattening

Microwave Toolbox Problem Reports
#1

Dear friends!

What is the standard way to prepare ASAR Single-look Complex images?

My region of interest is a mountain terrain out of SRTM survey. I have applied:

  1. Orbit file;
  2. Radiometric Calibrate to get sigma and beta;
  3. Then I try to apply Radiometric Terrain Flattening with GETASSE30. But it doesn’t work. CPU is heating, the status bar is “Writing” but in fact nothing to change. Since I thought my processor can’t manage with such large image I attempted to do that with cropped image 8x1 km. But result is the same. The TF file was written only with ASTER DEM but as a black square with gamma = 0 everywhere.
#2

This is because ASTER data is not downloaded automatically by SNAP and therefore no data can be generated. If you are interested in proper radiometric values along the mountain ridges you need to select SRTM 1Sec AutoDownload.

#3

Thank you, Mr Braun!

But as I said before, my ROI is not covered by SRTM and located at 61N lat.

With other DEMs the process is starting but actually there is nothing happened

#4

sorry, I overread that. The thing is you will probably not get very good radiometric corrections with a DEM of such low spatial resolution. Is it an option to you to just skip the terrain flattening part (it is not mandatory) and continue processing with Sigma0?
What is the aim of your study?
Maybe you can share a screenshot of the Sigma0 data.

#5

I don’t know, I think this correction may be crucial in such terrain since I attempt to mapping tectonic faults

After step 2 it looks like this

temp
temp.png1293×825 159 KB

#6

in this case I suggest to proceed with Sigma0 at first.

#7

Sorry, I do not quite understand. This image is Sigma0_VV image (after radiometric calibration). What should I do next?

#8

I meant you can skip the Terrain Flattening step and pre-process your image as suggested here: Radiometric & Geometric Correction Workflow (third option)

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