Local incidence angle images

[inglada]

Hi,
I recently discovered sarsen. This is a great tool that fills an important gap in the python geo/rs stack! Thanks!

I have started to poke around to generate local incidence angle images for GRD products on a target CRS (the one of the DEM), the goal being to have a corrected (geometry and radiometry) SAR image + the local incidence angle (LIA) as a single stack with 3 channels (VV, VH, LIA).

Actually, I would only need the incidence angle array extracted with xarray-sentinel1 (your other lib) orthorectified on the DEM and then I could use the DEM slope and aspect to compute the local angle.

Could you give me some guidance in how to generate the incidence angle grid on the DEM geometry? I can't wrap my head around how to use the sarsen API once I get the incidence angles from the gcp subgroup from xarray-sentinel1.

Thank you.