The process of removing the distortions caused by image perspective (tilt) and relief (terrain)

Image data acquired by airborne and satellite image sensors are affected by systematic sensor and platform-induced geometry errors. Topographical variations in the surface of the earth, the tilt of the sensor, and lens distortion affect the distance with which features on the satellite or aerial image are displayed.

Orthorectification is the process of removing these image effects for the purpose of creating a planimetrically correct image which allows for the accurate direct measurement of distances, angles, and areas.

Sensor specific information and digital elevation models are used to remove the image distortions.