Help！The space reslution will change after Range-Doppler Terrain corrcetion?
the resolution slightly changes because the Terrain Correction projects your data into a coordinate reference system and uses resampling (more on this here). Furthermore, SLC data has different pixel spacings in azimuth and range resolution which will be corrected during this step so that all pixels are squared.
If you want your pixel values to remain the same, you have to select Nearest Neighbor resampling.
Thanks.I just want to get The Backscatter coefficient. Should I need the DEM？
Thank you ！
would you please to take a look at this topic,
and this one
Yes. If you have topography in your study area, the true backscatter is distorted. It is therefore advisable to calibrate to Beta0 and then apply radiometric terrain flattening, as indicated by fahlahfakhri’s post.
Yes. Please note that resolution is not uniform before terrain correction either due to the foreshortening-effect.
You mean if the ROI is flat then I don’t need DEM? Thank you！
some geometric shifts can still occur caused by the slant-looking imaging geometry. But technically, ellipsoid correction works as well if your area is flat, yes.