Support z field in input tie point file for GenerateRPCModel and RefineSensorModel application
Currently, the GenerateRPCModel application reads (x,y) and (lat,lon) from the tie points file, and then retrieve the z from input DSM (elev.dem param). It would be interesting to also be able to retrieve the z field from the tie points file (optionaly).
This also apply to RefineSensorModel application as requested in #1872 (closed).
Edited by Julien Osman