Using snappy for Sentinel1 GRD Preprocessing

[CSchwenk]

@ABraun @arnab
I would like to go from the Sentinel 1 GRD Product to a Terrain Corrected Image following these steps (using snappy in python):

1. Read
2. Apply Orbit File
3. Thermal Noise Removal
4. Calibration
5. Terrain Flattening
6. Speckle-Filter
7. Terrain Correction
8. Write as .dim

I’m new to this community and would need some help to get started. Thank you!

[ABraun]

there are quite some scripts around which do this task, for example

• Sentinel-1 image pre-processing using snappy (clean and simple)
• A Python script to batch download and preprocess Sentinel-1 (includes downloading and bulk-processing, the pre-processing starts at line 64)

They should be a good start and help you getting into it, and modify it according to your needs.

[CSchwenk]

Thank you very much!

When I run the code from the first link, the part that executes the “do_thermal_noise_removal” function returns following error:

107         applyorbit = do_apply_orbit_file(sentinel_1)

–> 108 thermaremoved = do_thermal_noise_removal(applyorbit)
109 calibrated = do_calibration(thermaremoved, polarization, pols)
110 down_filtered = do_speckle_filtering(calibrated)

in do_thermal_noise_removal(source)
10 parameters = HashMap()
11 parameters.put(‘removeThermalNoise’, True)
—> 12 output = GPF.createProduct(‘ThermalNoiseRemoval’, parameters, source)
13 return output
14

RuntimeError: org.esa.snap.core.gpf.OperatorException: java.lang.NullPointerException

Do you know why this error is occurring and how I can fix it?

Thank you in advance,

CS