I am processing a S1 GRD scene (S1A_IW_GRDH_1SDV_20160314T015933_20160314T015958_010359_00F590_E4A5) with the following steps,
-Thermal noise removal
-Apply orbit file
-Calibration to beta0
-Radiometric terrain flattening (with SRTM DEM)
-Speckle filtering (optional)
-Range doppler terrain correction (RDTC)
-Linear to dB (for Gamma0 VV)
The Gamma0 VH band is processed to all NAN.
I can’t trace a reason behind this. The VH band in the GRD file looks alright.
since SNAP 8, the calibration to Beta0 is no longer needed before Terrain Flattening, but it shouldn’t make a difference actually.
Are you working with a graph file or do you process the data step by step?
I am aware about the Beta0 thing in SNAP 8 but just to remove any ambiguity I include this step. I processed the all scenes step by step. This is the only scene I am facing this issue with.
You can give it a try. I will be surprised if your results differ.
I have checked this scene and cannot reproduce the error, works fine on my side
This is strange.
Did you request the data from the offline repo in Copernicus Hub?
I notice you used a speckle filter between terrain flattening and terrain correction.
Can you post the graph for the entire chain?
I’ll try again with this.
I downloaded it from the ASF, but as the ID is the same, I expect the same product.
I did not apply a speckle filter, but multi-looking to speed up the processing after the flattening.
As you can see in the screenshot, my steps were Thermal Noise Removal, Calibration to B0, Terrain Flattening (SRTM 1Sec)*, Multi-Looking and Terrain Correction
- both bands looked fine after TF