Direct georeferencing (DG) is an efficient method of linking aerial images from drones or aircraft in such a way that they reflect the exact positioning on earth
.The earth reference points are measured using high-resolution digital cameras
, the Global Navigation Satellite System (GNSS) and inertial measurement units. The high-precision position accuracies
achievable with the GNSS receivers are in the centimeter range. Triangulation is used to create thedigital
surface models with direct georeferencing. In contrast to this technique, the traditional surveying of aerial photographs is carried out with Realtime Kinematic (RTK) or Post-Processed Kinematic (PPK).