How to maintain the accuracy of aerial surveying?
Surveying plays an important role in delivering major construction and engineering projects.
Increasingly though, traditional surveying methods are being replaced by aerial surveying services.
Rapidly developing drone technologies mean aerial surveying has quickly become one of the world’s most effective tools for drone spraying, mapping, measuring, imaging and other surveying tasks.
The secret to the success of aerial surveying lies in its accuracy.
Equipped with cutting edge sensors, cameras and GPS technology, surveying drones are capable of providing information with millimetre accuracy.
The accuracy of aerial surveying is critical to its adoption across the world.
To find out how operators deliver robust data with accuracy of aerial surveying, we’re going to dive into the control systems used in aerial surveying and learn how they provide millimetre-perfect results.
Is Aerial Surveying Accurate?
Modern aerial surveying systems are incredibly accurate.
The technology has been widely adopted across the world, and it’s now used to deliver construction, engineering, mining, agriculture projects and more.
With drones being capable of covering large areas in very little time, aerial surveying can provide critical information in moments that count.
Accuracy in aerial surveying depends on several factors, including the service being offered, the drone platform and the control method the operator is using.
In the right circumstances, drones can provide images, data and 3D models that are accurate to within 3-4 millimetres.
For larger mapping projects, drones are typically accurate to within several centimetres, depending on the drone’s altitude.
Regardless of the service, aerial surveying relies on one of the three control methods that we’ll outline below.
GCP – Ground Control Points
Ground Control Points (GCPs) are the simplest and most common form of aerial surveying control.
The GCPs themselves are physical markers that are placed in the survey area.
Each marker is assigned GPS coordinates to help with aligning the survey data in the post-processing phase.
Once each GCP has been placed in the survey area, drones are deployed to collect images, video and other sensor information.
During the aerial surveying process, the location of each GCP is noted by the drone, and special post-processing software is used to translate that information into useful data.
These post-processing softwares are able to reference the GPS coordinates attached to each GCP to geolocate images, creating maps and data with millimetre accuracy.
GCPs are common because they are a simple and highly effective solution.
The only drawback is that each GCP needs to be placed by hand, making them unsuitable for use in large areas or difficult terrain.
PPK – Post-Processing Kinematic
Post-Processing Kinematic (PPK) control methods bypass the need for physical markers.
Rather than aligning ground control points, PPK uses a GPS-enabled base station that calibrates information received from the drone with accurate GPS satellite data.
While aerial surveying drones have always been capable of providing GPS information, it’s only recently that PPK technologies have been developed.
By attaching the surveying drone to a PPK base station, the drone can simultaneously collect GPS data and survey information during its flight.
After the flight is complete, post-processing software matches the data from the drone with the GPS information from the base station.
This provides incredibly accurate results and is highly suited to mapping and surveying large areas or difficult terrain.
PPK controls offer a world of benefits, but the information often requires significant post-processing times.
So, while the technology is suited to a huge range of aerial surveying tasks, it may not provide the rapid results that some projects require.
RTK – Real-Time Kinematic
Finally, the newest and most advanced form of aerial surveying control is Real-Time Kinematics (RTKs). RTK control systems are similar to PPK technologies in that they combine drone data with GPS information to produce survey results without the need for physical ground control points.
The major difference between RTK and PPK systems is that RTKs are capable of processing the data that is collected in real time.
To do this, the drone’s controller is connected to its GPS base station, and software is used to process the GPS information and drone data during the flight.
This reduces the amount of time it takes to collect data and minimises the need for lengthy post-processing times.
The only drawback to RTK systems is the hardware investment.
Where PPK controls are compatible with a range of drones, controllers, base stations and software packages, RTK systems often rely on specific combinations of equipment.
This equipment represents a serious investment without providing major benefits over PPK systems in most circumstances.
Wrap up
Aerial surveying is an incredibly accurate form of data collection, and it’s quickly becoming one of the world’s most important tools for construction and engineering projects.
With the help of ground control points, drones can collect data with millimetre-accuracy, providing critical information in moments that count.
Hope you have now better understanding about the accuracy of aerial surveying.
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