Orthorectification is the process of removing the distortion within an image caused by terrain relief and the camera. This is done by modeling the nature and magnitude of geometric distortions in the imagery. Camera or satellite models in conjunction with limited ground control, allow construction of correction formulae that produce accurate, geometrically correct, map-oriented imagery. SATPALDA uses Leica Photogrammetric Suite to produce ortho images.
Geo Surveying Services offers various options of terrain datasets for orthorectification. The choice of DTM used for this process depends upon customers accuracy requirements.