Quick Answer
RTK and PPK both use a base and rover setup to give a drone accurate positions for its photos, but they correct that data at different times. RTK corrects the position live, during the flight. PPK records raw data during the flight and corrects it afterward, on a computer. PPK is more forgiving of a dropped radio link, while RTK gives you instant feedback that the fix is good before you even land.
The Shared Idea Behind Both Methods
Both RTK and PPK solve the same basic problem. A drone's onboard GPS alone is not accurate enough for photos that need to line up to within a few centimeters. Both methods add a second, ground-based receiver (the base) that either the drone or a computer later uses to correct the drone's raw position data.
The difference is entirely about timing: whether that correction happens in real time, during the flight, or afterward, once the drone is back on the ground.
How RTK Works on a Drone
With RTK, the base sends live correction data to the drone during the flight, usually over a radio link. The drone's onboard receiver applies the correction immediately, so each photo is tagged with a corrected position the moment it is taken.
This gives you a big advantage: you can watch the fix status during the flight. If the link drops or the fix quality drops to float, you know right away and can land, fix the problem, and re-fly if needed, instead of finding out after you get back to the office.
The downside is that RTK depends on a stable radio link between the base and the drone for the whole flight. Longer flights, hilly terrain, or obstacles between the base and the drone can cause the link to drop out at times.
How PPK Works on a Drone
With PPK, the drone logs its own raw satellite data during the flight, without needing a live link to the base at all. The base does the same, logging its own raw data independently. After the flight, you bring both data sets together on a computer and run a correction process that matches them up after the fact.
Because there is no live link needed, PPK is more tolerant of a base and drone losing contact mid-flight, since the correction step happens afterward using both complete data logs. This makes PPK a common choice for larger sites or areas where a stable radio link is hard to guarantee.
The trade-off is that you do not know your true accuracy until after the flight is processed. A bad recording on either the base or the drone can mean redoing the whole flight, and you find that out later rather than in the field.
Comparing the Two Directly
| Factor | RTK | PPK |
|---|---|---|
| When correction happens | During the flight | After the flight, on a computer |
| Radio link needed during flight | Yes, continuously | No, only raw logging needed |
| Feedback on fix quality | Immediate, in the field | Only after processing |
| Tolerance for link dropouts | Lower | Higher |
| Extra office workflow step | No | Yes, a post-processing step |
| Good fit for | Smaller sites, stable radio conditions | Larger or harder-to-cover sites |
Workflow Time and Cost
RTK generally saves office time, since the position data is already corrected when you land, and you can move straight into photogrammetry processing. PPK adds a post-processing step, which takes extra time and usually needs additional software.
Neither method is clearly cheaper overall. RTK-equipped drones and PPK-capable base setups both require similar receiver hardware. The real cost difference usually comes down to your workflow: how much you value instant field confirmation versus how much you need resilience against a dropped link on a difficult site.
Do You Still Need Ground Control Points?
Both RTK and PPK reduce how many ground control points, or GCPs, you need, but neither fully replaces them for demanding work. Drone RTK and PPK correct the camera's position, not necessarily every source of error in the final map, such as lens distortion or slight timing offsets between the camera and the GPS log.
For most general mapping, a small number of checkpoints held back and compared to the finished map gives you real proof of accuracy. For engineering-grade work like earthworks volumes or property boundaries, keep using a proper set of GCPs regardless of which correction method you fly with. Our guide to using an RTK receiver for drone mapping ground control covers that workflow step by step.
Which Should You Choose?
Pick RTK if:
- Your site is small enough for a stable radio link the whole flight.
- You want to confirm accuracy before you leave the site.
- You prefer a simpler office workflow with less post-processing.
Pick PPK if:
- Your site is large, hilly, or has obstacles that threaten a radio link.
- You are comfortable adding a post-processing step to your workflow.
- You need the flexibility of correcting data after the fact.
If you are still deciding on receiver hardware for either method, our Emlid Reach receiver guide and our base and rover setup guide are good next steps.