Georeferencing and orthorectification procedure

Hello there,
When I apply range doppler terrain correction I got an orthorectified image with the coordinates of top left corner and square pixels with constant size.
I’d like to understand how this is done, does anybody have any leads, link, paper or anything documenting how this is done in snap.
I am working with alos2 palasar 1.1 products and my goal is to measure the impact of the DEM on the backscattering.

ANy hint would be much appreciated.