Can someone tell me the preprocessing steps for Entropy-alpha decomposition of sentinel-1 dual pol SLC data?

I want have entropy-alpha decomposition but preprocessing steps are not working for me. Can anyone help me with the preprocessing step to achieve the entropy-alpha decomposition of sentinel-1 dual pol data.
Below are the steps I was doing but not working.

You can try this:

  1. TOPSAR Split
  2. Apply Orbit Files
  3. Calibration
  4. TOPSAR Deburst
  5. Polarimetric Decomposition
  6. Terrain Correction

Or using multilooking and speckle filter:

  1. TOPSAR Split
  2. Apply Orbit Files
  3. Calibration
  4. TOPSAR Deburst
  5. Multilooking
  6. Polarimetric Speckle
  7. Polarimetric Decomposition
  8. Terrain Correction
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Thank you for your Attention. Do, speckle filtering and multi looking important? I want to estimate soil moisture using sentinel-1 dual pol SAR data. @Ruben

I usually don’t use multilooking but I like to use speckle filter. I don’t have experience estimating soil moisture but you can have a look at this paper. It also contains a pre-processing flow chart.


Would you please to share the PDF file, in my case I couldn’t access it,

Sorry. I have attached the PDF file.

Soil moisture mapping using Sentinel-1 image.pdf (3.6 MB)

Can you help me regarding this. Following your pre-processing steps, When I am doing polarimetric decomposition (H-alpha dual pol) I am getting this error. :frowning:

Thanks for sharing the PDF, in general if you want to use GLCM, and classification, in general, speckle filtering doesn’t assist you, but, multilook could play a good role of speckle decreasing , especially if you increase the window size, I took a fast glance on the paper, but you could give try both and compare your results.

@abhichawda2107 I have never got that error. Which one of the pre-processing did you run? Could you provide me the image you got this error?

@Ruben Thank you for you earlier suggestions. I have resolved the problem. Now preprocessing I am using is as follow:

  1. Resampling
  2. TOPS-Split
  3. Calibrate
  4. TOPS-deburst
  5. TOPS-merge
  6. Multilooking
  7. Speckle filter
  8. Polarimetric Decomposition
  9. Terrain correction

I was bit confused working with sub-swaths. Now my problem is : I want both the output of H-A decomposition as well as sigma value as bands. But after doing terrain correction I am only getting H-A bands. For this I extract the sigma bands and H-A bands separately and then collocate them to get all the bands. Is there any other easier way of doing this??

Also I am not able to do collocation in graph builder. There is no option of selecting the master and slave in graph builder coming so it is giving error.

Would you please to clarify this step!

In simple terms if I explain, images of each sub-swath is of different dimensions (height and width). At the point of TOPSAR-Merge, if they are not resampled to a reference then Merge will not be correct (properly referenced).

Would you please to share the .xml file, if that possible!

spain_sigma_HA.xml (13.5 KB)

The resample is not needed at that point, TOPSAR-Merge will join the pieces correctly and the georeferencing is fixed by Terrain Correction.


Thanks for this. It worked fine without resampling :slight_smile: Could you please tell if there could be any correction(s) in any of the steps. Thanks in advance.

At the moment your steps are depending on the approach of your research, nothing wrong, as I mentioned in my previous post and @mengdahl also gave very nice comment concerning the resample step, now your BG, looks like this,

One thing you could do is, to apply speckle filtering before multilooking, as an trial step, and check up your result, I point to this issue according to this article,

Comparison of several multi-look processing procedures in INSAR processing for ERS-1&2 tandem mode


However, in your case the interferogram formation is not included in your steps, that’s why, it’s worth trying up. to be your BG as below,

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Hey really thank you for this so valuable information which is difficult to find in literature. I have fe more doubts. First one is during calibration, I have to save as complex output or just sigma0 band. And what if I do not process each sub-swath individually and just directly do:

  1. Calibration
  2. Deburst
  3. Speckle filter
  4. Multilook
  5. Polarimetric Decomposition
  6. Terrain Correction

Will it take care of each sub-swath?

It depends on the goal of your study and the approach you’d like to follow, this issue is well explained by our colleague @ABraun in the following posts,

It’s very easy to process each subswath individually and merge them later on,

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I have gone through the posts and got ample of information :slight_smile: Still I am not cleared with the difference between sigma0_VV and Intensity_VV ??