Post-processed kinematic (PPK) and real-time kinematic (RTK) are not new technologies. They’ve been used in terrestrial surveying for years to improve the accuracy of GNSS data. Both methods correct the location of drone mapping data and remove the need for GCPs, bringing absolute accuracy down to cm (sub-inch) range.
However, when you factor in obstacles and environmental conditions common to aerial surveying, the difference between a PPK drone and an RTK drone becomes more important to understand. In fact, choosing the best correction method for your surveys will save you time and project costs. But how do you know which is best? The answer can be found in learning about how each method works, including its inherent strengths and drawbacks.
What is an RTK drone (and how does RTK work)?
- An RTK drone carries an onboard GNSS RTK receiver that gathers data from satellites and a stationary base (ground) station to more accurately correct image location, in real time as it flies
- Satellite data—by itself, and in any case—is error-prone due to tropospheric delays, etc., providing a maximum accuracy of about 1 meter (3.3 ft)
- The data from a ground station is factored in to correct satellite signal error, bringing accuracy down to cm (sub-inch)-level range
- In the case of RTK technology, uninterrupted communications are required from the GNSS base station, through the drone base station to the drone
- When the drone lands, if all signals were constant, data with absolute accuracy is available for post processing into mapping survey results
What is a PPK drone (and how does PPK work)?
- A PPK drone flies with an onboard GNSS PPK receiver that gathers data from satellites and logs it for retrieval after the flight
- Satellite data—by itself, and in any case—is error prone due to tropospheric delays, etc., providing a maximum accuracy of about 1 meter (3.3 ft)
- The satellite data from a GNSS receiver on a nearby base (ground) station is collected and, after the flight, it’s factored in with the drone data to correct satellite signal error, bringing accuracy down to cm (sub-inch)-level range
- In the case of PPK technology, neither GNSS base station to drone base station, nor drone base station to drone correction data communications are required; only the telemetry between drone and drone base station is needed
- When the drone lands, a correction process needs to be applied through a suitable software, e.g., WingtraHub. Data with absolute accuracy is then available for post processing into mapping survey results