Importing fies to SNAP

snap Problem Reports
#1

Hi,

I have a problem importing the files to SNAP.
So, I have binary files, I tried to import but it is not supported in SNAP. Then I convert to Geotiff using QGIS3. It can be open, but later I cannot do any further anlysis because it is said that :“the input sh0uld be SAR Product”. I have read that any file extraction should be done first in SNAP so the metadata is not loss. But due to the condition that my original file is binary files, I have to convert first. Does anyone have a clue, what should I do to solve this problem?
Kindly help.

Thank you

#2

What files are you trying to import?

#3

This is ALOS Palsar 1 and 2 product, these files has been pre-processed.

#4

You should import the original products, without pre-processing that got rid of the metadata.

#5

Were these bin files pre-processesd in PolSARpro? If so, what information do they contain?

#6

These data were pre-processed IDL/ENVI and GAMMA software.Those contain everything, The pre-processing was done completely. I only need to extract the backscatter value and do classification afterwards. I got these products from third person.

#7

I see. SNAP is able to import a lot of formats but there are limits for individually pre-processed files because the metadata structure often does not match.

What do you mean by “extract the backscatter value”? At which step in SNAP do you get the error message " “the input sh0uld be SAR Product”?

#8

So I am gonna convert DN to NRCS, normalized radar cross sections. But it got error, I check the metadata was lost. A lot of information are missing.
And I just do trial with radiometric, geometric calibration, but the message error “input should be sar poduct”. I think the metadata is the main problem here.
What do you suggest, if I have binary data and want to process in snap?

#9

You can at least derive the calibrated backscatter by yourself using the calibration equation from the ALOS documentation

ALOS PALSAR: https://www.eorc.jaxa.jp/en/about/distribution/info/alos/20090109en_3.html
ALOS-2: https://www.eorc.jaxa.jp/ALOS-2/en/calval/calval_index.htm

However, without metadata on the geocoding, the Terrain Correction won’t work as well.

Maybe you can try ASF MapReady: https://www.asf.alaska.edu/data-tools/mapready/
It can import multiple data products (including bin from GAMMA), perform calibration and terrain correct the data with a DEM.

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#10

Thank you, I am going to do this. Hopefully it will work.

Have a good day.

#11

Hello @ABraun and forum
I was trying to import a binary file which C2 matrix data to SNAP
While doing this I got error “Input should be a SAR product”

Please guide me

Thank you

2021-12-28
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#12

You can’t use the mask as source for the terrain correction. It does not contain the necessary metadata. you need to use one of the many supported SAR data products.

#13

I have processed it in PolSARpro for NLM filtering and generated a C2 matrix
then I was trying to import to SNAP to proceed further (Change detection)

#14

You can check how files from PolSARpro can be imported back into SNAP here: importing Sentinel-1 datasets for advanced polarimetric processing in PolSARpro - YouTube

#15

The product that I am processing is GRD
while generating Pol matrix it is asking for SLC only

In the youtube link, subset is done through graph. But i have already processed after doing subset earlier.
Is there any other way that you can suggest.

Thank you

#16

I think it doesn’t really matter which steps are applied, but the graph allows to export to this specific format which feeds into PolSARpro. I am not aware of another way, but there might be several.