Drone Data Accuracy Part 5: Ground Control
In the pursuit of accurate data, there is no looking past ground control. Other technologies such as on board RTK/PPK will provide improved accuracy in the air, but this does not automatically translate to the same accuracy on the ground. Terrain models corrected with on board RTK and PPK data are still more susceptible to turbulence, vibration, and camera calibration errors than models generated using ground control points.
Combined errors of ten degrees or more in a drone’s measured pitch or roll can introduce tens of centimeters of error in the final model, if no GCPs are in place. With this in mind, achieving centimeter ground accuracy in surveys with on board PPK/RTK is significantly more difficult without the inclusion of ground control points.
Elevation of site surveyed seven times with AeroPoints compared to one flight with geotags only
Absolute accuracy with GCPs can be reined in from meters to centimeters making them the gold standard for survey-grade data.
Example planar shift between data sets generated with AeroPoints and those using just on board geotags
Traditionally, setting up ground control points was slow, costly, and complicated. However this practice is changing with the recent launch of Propeller AeroPoints. These smart ground control points with inbuilt GPS are easy-to-use and capable of capturing incredibly accurate positional data.
If you are considering using ground control for drone surveying, visit the AeroPoints web page to find out more.
Accuracy in, accuracy out
Almost every aspect of a drone survey job — from the drone and camera used to the flight conditions and ground control implemented can affect the accuracy of the final data.
When submitting your data for processing it’s important to understand that a 3D model is no more or less accurate than the data used to generate it. Consider accuracy requirements when setting up capture tools for the next flight and you’ll be producing high-quality sources for your maps and models.