Another GNSS receiver is installed in a reference station . The reference station generates correction data - i.e. deviations from a position - which can be utilised in two different ways:
RTK (= Real Time Kinematic)
The correction data is sent to the drone in real time and the exact, corrected position data is saved in the metadata of the captured image. The accuracy is between 1 and 2 cm.
PPK (= Post-Processed Kinematic)
The position data is corrected afterwards. Post-processing work using small software tools must be planned in order to obtain exact data. The additional effort is rewarded with an even higher accuracy of < 1 cm, but this is not useful for every application.