RTK vs PPK: Which Is More Accurate for Drone Mapping?
- Anvita Shrivastava
- 1 day ago
- 6 min read
Drone mapping has revolutionized surveying, construction, agriculture, infrastructure inspection, mining, and GIS data collection by enabling high-resolution aerial imaging in a short time. Yet, getting sharp images is just half of the work done. The geolocation of each captured image is critical, as the accuracy of the orthomosaic, DEM, DSM, point clouds, and 3D models depends on it.
This is why RTK (Real-Time Kinematic) and PPK (Post-Processed Kinematic) positioning methods come in handy.
These two technologies make use of GNSS corrections to increase the positional accuracy of the collected drone images and are able to provide centimeter-level maps. However, RTK and PPK are not the same, and one of them cannot be considered more accurate than the other in all cases.
Therefore, RTK vs PPK: which one is more accurate in drone mapping? The actual answer to the question is that both are highly accurate if correctly set up. PPK may be more reliable in situations when it is hard to maintain the real-time connection.
What Is RTK in Drone Mapping?
Real-Time Kinematic (RTK) is an example of GNSS positioning that provides position correction of a drone in-flight.
An RTK-capable drone normally gets signals and corrections from either:
A local GNSS base station
CORS or NTRIP networks
Any other suitable correction source
These corrections allow the drone to calculate the precise position of each shot picture.
In contrast to ordinary GPS/GNSS receivers capable of delivering positioning information with meter-level accuracy, RTK positioning can deliver centimeter-level positioning accuracy under certain conditions.
How RTK Works
A regular RTK drone mapping process includes the following steps:
GNSS satellites send positioning signals.
The base station or correction source calculates satellite-based errors.
The corrections are sent to the drone.
The drone applies the corrections through its RTK receiver.
Precise position data is attached to each photo.
Photogrammetry software creates mapping products using precisely geo-tagged pictures.
The main benefit is that the position corrections are available during the flight process.
What Is PPK in Drone Mapping?
In Post-Processed Kinematic (PPK), the GNSS data collected by the drone is processed later on.
Rather than sending the correction data continuously to the drone, the drone records the raw GNSS data during the flight. The reference GNSS data is recorded by a base station or CORS network. Post-flight processing of these two datasets allows determination of the corrected image coordinates.
Simplified process of using PPK is:
The drone flies to capture images along with GNSS data.
Reference GNSS data is recorded by a base station or CORS network.
The drone finishes the mapping mission.
Post-processing of raw GNSS data occurs post-flight.
Assignment of corrected coordinates to captured images.
Photogrammetry software uses these coordinates for reconstruction.
PPK makes it unnecessary for the drone to have a continuous correction data link with the base station.
RTK vs PPK: Key Difference
The fundamental difference is when GNSS corrections are applied.
Feature | RTK | PPK |
Full form | Real-Time Kinematic | Post-Processed Kinematic |
Correction timing | During flight | After flight |
Real-time positioning | Yes | No |
Continuous correction link | Usually required | Not required between drone and base |
Post-processing | Limited/optional | Required |
Dependence on communication | Higher | Lower |
Workflow | Faster field-to-result | Requires additional processing |
Accuracy potential | Centimeter-level | Centimeter-level |
Best advantage | Immediate corrected positioning | Robust post-flight correction |
What matters is the fact that RTK and PPK are technologies of accuracy, not accuracy classes. In ideal circumstances, both systems have the potential to produce very accurate geolocated images.
Is RTK More Accurate Than PPK?
They are not necessarily.
A properly configured RTK system and a properly processed PPK system can both result in centimeter-level positioning. The actual accuracy of the produced map will be influenced by many other factors rather than correction type.
Some of the factors include:
Quality of GNSS receiver
Visibility of satellites
Base or CORS station quality
Distance from the reference station
Quality of correction
Camera calibration
Resolution of the images
Image overlap
Altitude of flight
Shutter parameters of the camera
Accuracy of checkpoints
Photogrammetry processing
Coordinate reference system
Terrain and environmental conditions
PIX4D mentions that absolute accuracy will largely depend on the accuracy of the image geolocation and positioning; RTK/PPK can greatly enhance the absolute accuracy. Yet, maximum possible mapping accuracy will never exceed image geolocation/GCP accuracy.
When RTK May Be the Better Choice
RTK becomes especially helpful when one requires instant positioning data during a mission.
Real-Time Positioning Data
RTK supplies the operator with corrected coordinates in real time while flying a drone. It may be helpful in cases when a user requires reliable positioning data during the data collection process.
Increased Speed of Field Work
As the corrections are made during the flight, it might not be necessary to perform a significant amount of GNSS processing after the flight to prepare imagery for photogrammetric processing.
Repeated Mapping
RTK becomes handy in case of repeated mapping when the correction network remains the same.
Agriculture Mapping
The precision agriculture workflow may benefit from the real-time position data when drone imagery should be aligned with other precision machines. It is especially relevant in the case of PIX4D, which states that compatibility of the RTK correction network is important in this case.
When PPK May Be the Better Choice
The main benefits of PPK come out when a continuous correction connection is hard to provide.
Problematic Areas in Terms of Communications
RTK usually relies on stable communication to provide real-time corrections. Obstacles such as buildings, vegetation, landscape, distance, or weak network coverage can influence the communication process.
PPK collects all the required GNSS observations for future processing and decreases dependence on continuous communication to get corrections.
Mapping of Corridors
Mapping projects like roads, pipelines, railways, power lines, and other corridor-mapping projects often have a problem with providing stable communication. Image geolocation using RTK or PPK is highly recommended for such projects because of possible complications in reconstruction geometry.
Remote Mapping Sites
Remote places, which lack cellular and correction network communications, can benefit from the use of PPK technology.
Additional Control in Post-processing Stage
PPK provides an opportunity for the operator to get raw GNSS observations, which can be further processed during the post-mission stage.
RTK vs PPK Accuracy: What About Centimeter-Level Results?
RTK and PPK drone systems often claim centimeter-level accuracy. But just because the RTK/PPK system provides centimeter-level accuracy, that doesn’t mean that all features in the final orthomosaic or 3D model will have centimeter-level accuracy.
For example, according to PIX4D, in the case of a 5 cm GSD project with an RTK/PPK drone, expected relative accuracy would be around 5-10 cm horizontally and 5-15 cm vertically depending on the project conditions. The absolute accuracy will depend on the accuracy of RTK/PPK positioning and photogrammetry processing.
Here’s why it is important:
Accuracy of GNSS positioning ≠ Accuracy of mapping.
GNSS positioning tells you how accurate the camera position was at each point in time. Photogrammetry will tell you how accurately those pictures were turned into spatial data.
Which Is Better for Surveying?
While deciding between RTK and PPK technology for professional drone surveying, environmental conditions play an important role.
Choose RTK if:
There is a stable correction connection.
Real-time positioning is essential.
There is a need for streamlined workflow in the field.
The survey area has good communication coverage.
GNSS positioning is crucial.
Choose PPK if:
Communications are not reliable.
Surveying involves remote locations.
Mission involves a large area or long corridor.
There is a need to reduce reliance on real-time correction connections.
There is no problem with post-survey data processing.
In case of high-value surveying missions, RTK or PPK combined with accurate checkpoints is more efficient for quality control.
RTK vs PPK: Which One Should You Choose?
There is no absolute winner in all cases.
RTK is better if real-time positioning, fast field operations, and reliable connection for corrections are needed.
PPK is better if reliable communication, unmanned and remote operations, flying at long distances, and post-flight control are needed.
Regarding accuracy, both RTK and PPK are capable of providing cm-level drone mapping accuracy if all of the following aspects (hardware, corrections, flight planning, images and image processing, and quality check of the process) are taken into account.
It means that the most important thing to consider is not whether a drone uses RTK or PPK, but the entire workflow of the process.
RTK and PPK are now popular methods for making high-resolution maps using drones. The former uses GNSS corrections in real time, while the latter calculates GNSS-corrected locations post-flight. Both techniques allow to substantially increase in the accuracy of geolocation of drone imagery in comparison with standard GNSS-based positioning.
If the project requires reliable correction access and fast location determination, RTK will be a good solution. In cases of complicated operations, lacking reliable communications, etc., PPK may offer a more efficient workflow.
However, for the best possible accuracy of drone mapping, it is crucial to regard RTK or PPK as only one element of a geospatial workflow. Flight planning, image acquisition, suitable GSD, proper coordinate systems, GCPs (if needed), and independent checkpoints are equally important.
For those organizations that make orthomosaics, DEMs, DSMs, point clouds, topographic maps, and other geospatial data, the selection of a GNSS positioning workflow will greatly increase the accuracy and efficiency of their operation.
For more information or any questions regarding RTK and PPK, please don't hesitate to contact us at
Email: info@geowgs84.com
USA (HQ): (720) 702–4849
India: 98260-76466 - Pradeep Shrivastava
Canada: (519) 590 9999
Mexico: 55 5941 3755
UK & Spain: +44 12358 56710
Comments