With the release of DJI’s Phantom 4 RTK drone last year (and the Propeller PPK solution), there’s been a lot of talk about PPK and RTK drone surveying. We wanted to give a quick explainer of what PPK drone surveying is and what its benefits are.
(If you want a more in-depth explanation, or want to learn how ground control and AeroPoints play into all of this, check out our blog post How It Works: PPK vs. GCP Drone Surveying.)
First, you might be wondering why a workflow that uses an RTK drone is called “PPK.” This is where things can get confusing because we’re not strictly comparing like to like.
PPK isn’t hardware, but rather a different processing workflow using RTK data.
What RTK technology is and how it works
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 the image.
An active base station on the ground sends raw GPS data to the drone. Then the drone’s onboard GPS combines that info and its own observations to accurately determine its position relative to the base.
To achieve this, the RTK drone must stay connected to the base station while it’s gathering data. Unfortunately, signal loss can occur during turns, likely due to antenna orientation, and other instances. If this happens, while it tries to get a lock again, data becomes unreliable.
What PPK drone surveying is and how it works
Now, when we talk about a PPK workflow, we’re talking about processing data after your drone flight is complete. PPK stands for “post-processing kinematic.”
With PPK, the drone will geotag X,Y,Z coordinates to each image based on that on-board GPS unit. While this is happening, a base (be it a base station, an AeroPoint, or CORS network) is also recording positional information, but with much more accurate triangulation.
After the flight is over, those two sets of GPS data are matched up using the photo timestamp. Then the initial, less-than-accurate onboard GPS data is corrected, giving precise geotags for the imagery
While “real-time” technologies are appropriate in some situations, post-processing flight data using a PPK workflow brings an additional layer of reliability to your surveys.
If you want a deeper dive into how RTK technology and ground control points play into PPK surveying like Propeller PPK, check out our blog post, How It Works: PPK vs. GCP Drone Surveying, for more information.
Want to get consistent 1/10ft (3cm) accuracy on your worksite? Get a quote for Propeller PPK today.