What is RTK?
Real-Time Kinematic (RTK) positioning allows UAV systems to collect highly accurate geospatial data during flight. This technology enhances the GPS signals received by the drone in real time, correcting any positioning errors on the fly and delivering centimeter-level accuracy. RTK technology provides real-time corrections to GPS data by utilizing a base station that communicates directly with the drone. This setup allows for immediate positional accuracy during flight, making it ideal for applications requiring instant data. Every GPS-enabled UAV uses satellite signals to determine its position. But standard GPS alone can have a positioning error of 1 to 5 meters due to factors like satellite clock drift, signal multipath, and atmospheric interference. RTK solves this by providing real-time correction data.
RTK Workflow
An RTK enabled drone is required along with base station positioned over a known point connected to a CORS network needs to accurately mark the location of the image in real time. Real-time kinematic (RTK) processing on a drone records GPS information and geotags images as they’re captured during flight. The GPS location is recorded for the center of each image. As the UAV continues to fly, base station actively transmits raw GPS correction data. The drone’s onboard GPS receiver uses this information, along with its own satellite data, to calculate its precise position relative to the base station in real time.
For RTK to work correctly, the UAV must maintain a continuous connection with the base station throughout the flight. If that connection is disrupted—whether due to signal interference, obstacles blocking the signal, antenna misalignment during sharp turns, or poor coverage—the accuracy of the data suffers. Until the UAV re-establishes communication with the base, positional data may be unreliable.
Accuracy of RTK
RTK drone positioning relies mainly on information broadcast from satellites and a ground-based receiver. With these two systems combined, you can expect to achieve an accuracy range of up to 1-3cm in the horizontal direction. And 2-5cm vertically.
Pros and Cons of RTK
Pros | Cons |
|---|---|
Immediate data accuracy during flight. | Higher equipment and operational costs |
Reduces the need for extensive ground control points. | Dependent on a stable communication link between the drone and base station |
Suitable for time-sensitive projects. | RTK performance tends to degrade with distance from the base station. |
Reduced post processing |
In the realm of UAV (Unmanned Aerial Vehicle) surveying, achieving high-accuracy geospatial data is paramount. Three primary techniques— Ground Control Point (GCP), Real-Time Kinematic (RTK) and Post-Processing Kinematic (PPK)—are employed to enhance dataset accuracy. Understanding their differences, advantages, and ideal use cases is crucial in order to determine the most suitable method for a given project.
