Cover large areas
Achieve 1cm accuracy
and leverage RTK
Real-Time Kinematic (RTK) with drones utilize a standalone "base station" that actively sends GPS data to the drone. Post Processing Kinematic (PPK) is an index of process performance which tells how well a system is meeting specifications . PPK calculations use actual sigma (sigma of the individuals), and shows how the system is actually running when compared to the specifications.
Ground control points are marked points on the ground with known geographical location within your survey location. When used in photogrammetry, operators use lay large visible "targets/markers" to make them easy for the camera to capture. Then a survey grade GPS receiver is used to collect precise GPS coordinates of the centre of that target. A number of GCP's are needed to be spread throughout your survey area, depending on the size of the area.
GCP's can be used as "checkpoints" during data processing to verify and or correct the accuracy of projects. One stipulation of GCP's is the time required set and create them, which can decrease workflow efficiency. GCP's are not always necessary depending on the application the project output is being used in, for instances like creating marketing material or scouting.