Geometric Terrain Correction error message

Processing new ASAR geotagged data and would like to

  1. update georeference
  2. apply terrain correction with an external DEM applied

but SNAP returns the following error message:
for both 1) and 2) “Metadata radar frequency has not been set”
It looks like it cannot read Metadata file?
This is not a standard product, so I expect issues but any guidance on how to solve this issue would be very much appreciated. Thanks

Where did you download the ASAR data and what exactly did you do at “update georeference”?

I am working on a NASA project at USF using new L-S ASAR data, so currently unsupported on SNAP. I can open Geotiffs in SNAP and view them but SNAP seems to have a problem recognizing it’s a SAR data whenever I select radiometric terrain flattening for example - a message “Input should be a SAR product” appears. Similarly, a message “Metadata radar frequency has not been set” appears when I try to do any Geometric processing. My ASAR data files contain tiffs, h5, META and grid data but for some reason SNAP cannot read them correctly, returning these error messages.

Your guidance is much appreciated

I’m afraid you cannot do much with unsupported sensors. SNAP needs to have the metadata (incidence angle, wavelength, orbit position…) for many SAR-related processing steps. All these are not contained in a GeoTiff.

I was hoping that I would be able to manually enter that information during open/import file step, as I do have all that information (incidence angle, wavelengths, orbit position…) in my Metadata file. If there is an alternative way of making SNAP read this data or another more ‘manual’ data input approach, your guidance would be much appreciated.

Many thanks

the entire process is quite complicated (https://github.com/senbox-org/s1tbx/blob/master/s1tbx-op-sar-processing/src/main/java/org/esa/s1tbx/sar/gpf/geometric/RangeDopplerGeocodingOp.java) so unfortunately, these metadata cannot be inserted manually. I’m sure besides the ones I mentioned there are a lot of others which are required for this task.
Is it an option to geocode your data with rubbersheeting techniques?

Thank you for your suggestions but ‘rubbersheeting’ is not useful for my project. I actually want to do the Radiometric Terrain flattening and not the geometric one. Would the code for Radiometric Terrain flattening be as complicated to enter manually too from my Metadata?

I was wondering if alternatively there is a way of creating a personalized data reader code (or plug-in) for SNAP to be able to open and read my ASAR-ISRO data. Any guidance on how to create that?

Many thanks

there is pseudo-code of how the terrain flattening is done in figure 4 of this article. If you are able to implement that yourself, you can give it a try.
SNAP offers no tool to manually enter metadata, sorry.

Thank you for your guidance on this matter. Best wishes