Drone-based surveying is becoming increasingly important on construction sites. Compared with traditional labor-intensive surveying methods, it collects data quickly and efficiently, so many construction companies are actively adopting drones.
However, for drone survey data to be reliable, the analysis output must match the actual terrain as closely as possible. This requires not just capturing images with a drone, but also position-correction work such as installing GCPs (Ground Control Points) or using RTK drones.
In this post, we'll take a closer look at why this position-correction work matters and how to apply it.
On construction sites, the term 'control point (CP)' may be more familiar. Just as a CP serves as a reference point for surveying, a GCP (Ground Control Point) aligns the coordinates in drone imagery precisely with real-world positions.
By performing post-processing with GCPs, you can obtain precise analysis data with a centimeter-level margin of error, making GCPs essential when accurate survey values are required or for tasks where real-world coordinates matter, such as earthwork volume calculations.
While drone-based surveying is certainly far more convenient than traditional methods, installing and managing GCPs is not exactly easy. For accurate correction, GCPs must be placed evenly across the site at intervals of 200–300 m, and the job doesn't end once they're installed—as the work progresses, they can easily get buried under soil or disappear.
As a result, you have to reinstall GCPs for every flight and re-check their positions during analysis. Carrying out this work continuously on a busy site can be cumbersome.
If managing GCPs like this proves difficult, you can use RTK (Real-Time Kinematic) drones as an alternative.
🔗 You can find detailed information about GCP installation and the analysis process in the guide below.
An RTK drone is a drone that performs GPS correction at the moment of capture, adjusting position data in real time to deliver high accuracy even without GCPs. With the RTK method, the drone communicates continuously with a base station while capturing images, correcting position data in real time. This makes it possible to generate 3D models based on accurate coordinate information without installing separate GCPs.
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The image above is a chart comparing surveying accuracy from GNSS through PPK. GNSS refers to what we commonly know as GPS; PPP is the position value of the surveying equipment itself; RTK Fix is the RTK drone described earlier; and PPK refers to values obtained by post-processing the RTK drone's data.
It may look a little complicated, but simply put, you can understand it as follows: surveying values based on GNSS have an error of about 10 cm, GCP-based values 3–5 cm, and the RTK method less than 1 cm. This provides enough precision for typical construction sites, but when even higher accuracy is required, you can consider combining RTK and GCP to maximize surveying accuracy.
🔗 Inquire about purchasing an RTK drone
That said, operating an RTK drone yourself can also come with practical burdens. First, you need personnel on site who can operate the drone, and you also have to own the RTK drone itself. If these reasons make drone surveying difficult to adopt on your site, try Meissa's earthwork volume calculation service.
Meissa's earthwork volume calculation service provides not only drone-capture services using both RTK drones and GCPs, but also a high-quality data package you can use immediately in the field—including an earthwork volume table (.xlsx) and cross-section drawings (.dwg) based on precise survey data. If you want more accurate and reliable data, feel free to reach out anytime via the inquiry button.
🔗 Inquire about the earthwork volume calculation service
