Overview
When it comes to data collection for mapping, 3D mapping, or any other type of drone mission accuracy of the data is vital to achieve the best results.
Your client or stakeholder will rely on the accuracy of the data you have collected to ensure their project is as precise as possible, this may include tasks such as 2D mapping or 3D models for CAD, architecture, and construction work.
So how do we ensure the accuracy of the data?
This is where RTK and PPK play a huge part.
What is RTK?
RTK stands for Real-Time Kinematic and is a technique used to increase the accuracy of GNSS (global navigation satellite system) positions using a fixed base station that remotely sends out data to a moving receiver.
Traditional GNSS receivers, like the ones in your phone or tablet, usually only give accuracy up to 2 to 4 meters or 7 to 13 feet.
Some of the latest drones available have RTK built in, a good example of the most popular RTK drones are both the DJI M300 and the DJI Phantom 4 RTK
With the addition of an RTK unit and base station, this accuracy can be pushed down to mere centimeters.
For more information on using RTK with a base station please see our post:
RTK, as the title suggests, is a real-time method of collecting high-quality data whilst in the field where the collection and correction of data is done as you fly.
What is PPK?
PPK stands for Post Processed Kinematic and is a method of correcting the data after the flight has taken place and the data has been uploaded.
The data can be uploaded to specialist software that enables the correction of data after the flight has occurred, hence Post Processed. This software can be cloud or desktop based depending on your preference.
PPK works by taking the drone's data, which will be geotagged, and combining that with the base station's positional information.
Once the flight has been completed both the drone geotagged data and the base station data are matched up after uploading using your chosen PPK software. The less accurate geotagged data from the drone is corrected providing a more precise picture of your captured asset.
PPK, as the title suggests, is a post-processed method of collecting and correcting high-quality accurate data by importing the data into a PPK software once your flight has been completed.
RTK vs PPK
So as you can see there are two different methods of ensuring your data is accurate, RTK and PPK, but what are the advantages and disadvantages of using either of these methods?
RTK Pros and Cons
You would think RTK would be the clear winner as data is corrected in real time (as the title suggests) and yes while this is a huge advantage it also has its downsides.
RTK requires a consistent data connection and when flying over large areas or built up towns or cities outages can happen and if you encounter and outage you will end up with gaps in your RTK correctional data and therefore the possibility of incorrect or inaccurate data.
RTK works well in large open areas where there is nothing to disrupt or block the connection.
PPK Pros and Cons
PPK data collection would initially cut down time in the field as there would be no need for a complicated set up and a consistent data connection would also not be required.
PPK doesn't reply on a strong signal or a constant solid connection between the drone and the base station meaning they can be flown in more built up and challenging areas where signal loss may be an issue.
The more time consuming part of the data collection would be when after the flight when the data has to be imported and corrected via a third party software application. This would allow for the correction of GPS data and processing of the data.
In the video below, Alex and Varun from Hammer Missions discuss both RTK and PPK along with GCP's
Step-by-Step PPK Guide with Hammer Missions
Now we have looked at what RTK and PPK are and their pros and cons we can show you how to initiate PPK with Hammer Missions in our step-by-step guide:
1: Connect to RTK with Hammer Missions during flight, select RTK in the Hammer App as highlighted in red.
2: Select the RTK toggle and switch it to on
3: Fly your mission and collect the data using Hammer Missions
4: Once you return to the office extract the data from the SD Card
5: You will see that RINEX (receiver independent exchange) files are included along with your images
6: You will now need to import both the RINEX files and your images into a third party PPK software, KlauPPK, REDtoolbox and Emlid Studio are some examples of this type of software.
7: Process the data in your third party software.
8: Once the data has processed you will be able to output the corrected geotagged data in various formats to use for accurate post processing.
Summary
In summary both RTK and PPK have their place in the collection of high quality data in the drone industry, both have unique qualities and really depend on your use-case.
RTK is ideal for large open areas and corrects your data in real time but takes longer to set up.
PPK is ideal for quicker set up speeds and more built up environments but has a longer post processing time.
If you would like to learn more about setting up RTK with Hammer Missions please feel free to read our post:
Conclusion
We hope this blog post helps you understand how to conduct a Drone PPK Workflow with Hammer Missions.
If you'd like to learn more about how to high-quality data and get the most out of your drone missions, please feel free to visit our learning resources.
If you haven't got a Hammer account as yet and would like to try Hammer Missions you can get started on our free trial.
To learn more about our enterprise solutions, including mission collaboration, data processing, and AI solutions, please contact us at team@hammermissions.com.
We look forward to hearing from you.
— Team at Hammer Missions