ALOS2 FBD 1.1 layover-shadow mask

Hello, I am trying to process and terrain correct ALSO2 1.1. I need the shadow-layover mask to exclude distorsion areas from further processing in retrieval forest biomass. I am using Sigma_00 as input and SRTM DEM 1sec.
I have a doubt as I gen generate masks from both 1) SAR simulation 2) SAR simulation terrain correction tools (in Geometric–>Terrain Correction menu).
The two masks are different, and it is logic as the second tool does TC and the first not. My question is: which mask should be used to exclude data not useful for retrieval purposes, so that do not reach the target?
Thanks for helping claryfing this doubt

intuitively, I’d say the mask computed in slant geometry (option 1) is more correct. But if you are going to project the data to ground range anyway, you can as well use the mask after TC.

How much do they differ?

Thanks for your reply, in effect when doing TC on the layover shadow mask the result is very very similar, so I did not consider that changing the geometry would have change so much the mask too! Thus my choice is to go directly for SAR simulation TC to produce the mask and exclude the areas. thanks for your support!

Hello, I hope you can support me with correct preprocessing steps for ALOS2FBD for biomass retrieval. I did calibration, multilooking and speckle filtering. Next would be terrain correction. After that, do I still need a layover_shadow mask to exclude distorsion areas from retrieval, or the TC procedure fix most of those problems? And which is the correct procedure to produce the mask? I guess the steps are to perform the Simulation step and then TC on the simulation outputs. If I go directly on TC there is no mask produced. Thanks for the support

TC mostly corrects foreshortening. Unless you are in very mountainous areas, layover and shadow can nearly be neglected. You can run the SAR Simulation Terrain Correction once which allows to output this mask, to check how many pixels are effected.

To reduce radiometric distortions, it can make a difference if you first calibrate to Beta0 and then apply Terrain Flattening. But again, this depends on the degree of topography in your area.