Is A Drone Survey Accurate?
Can a drone survey be accurate, the short answer is YES!
But the accuracy of a drone survey is dependent on a number of factors including the amount of overlap between photos, the flight speed, the resolution of the camera and the type of lens used.
What do we mean by accuracy?
In any type of surveying, accuracy and precision is critical in determining the success of a project and there are two terms that you will hear about:
- Relative Accuracy: This refers to the precision of measurements relative to each other within the dataset.
- Absolute Accuracy: This ensures that the data collected is closely coordinated to a known coordinate system.
As surveyors, we are concerned with recording precise and accurate measurements, and we go about achieving this by using the latest technology and ensuring that we can verify our data.
How can we ensure that our data is accurate and precise?
To ensure our data is precise, we fly with a high overlap between images and use high resolution cameras. We ensure that the flight height allows us to achieve a GSD (ground sampling distance) that is appropriate for the work. Here at Merrett Survey Limited, we use drones with RTK GPS modules, and we record data at a GPS base station, so that we can get very accurate coordinates for the image centres. We lean towards post processing the data to get the best possible accuracy. We also survey Ground Control and Ground Check points so that we can improve and check the accuracy of our data.
For a typical topographic survey, our data is accurate to approximately 2cm. However, this can be improved to sub-centimeter if required (for example, when surveying a building facade).
Why Carry Out a Drone Survey?
Mapping:
A drone survey can map a large area of land in a short space of time. In the example below, this site was surveyed in around 30 mins and achieved a resolution of 2cm per pixel. A 1:200 topographic map was produced of the site. Typical outputs include Digital Terrain Models, contours, ortho-images and more…
LiDAR:
If a site has a lot of foliage, then a drone equipped with a LiDAR sensor can be used to penetrate the foliage and record the ground shape underneath. We recently surveyed a stretch of road with steep banks on each side. Using a LiDAR equipped drone, we were able to record data underneath the tree canopy without having to resort to difficult rope access to record the ground shape.
Asset Management:
A drone survey is a fast and safe way to survey a site, they can be used to monitor progress on a construction site and they can get where people can’t access safely. For example, they can survey roofs, bridges and other inaccessible or difficult to access places such as electricity towers. In this example, a drone is creating an accurate 3D model of this chimney and recording high resolution imagery of the condition of the brickwork at the top of the tower.
Visualisation:
We fly drones and produce high quality video for clients. Applications include images showing construction progress, site overviews, 3D models and more…
Volumetric Surveys:
A stockpile survey, using traditional surveying methods can be a labour intensive and time-consuming process. A drone survey is safer, can capture the data and produce more accurate volumes rapidly and cost effectively. The image below shows a project where the sea wall and immediate surroundings were mapped and beach volumes computed.
We Work Worldwide!
As dedicated surveyors at Merrett Survey, utilising UAV surveys means that we collect only the most precise results for our clients, that can improve the operator’s ability to perform their job.
Conducting UAV Surveys In Greenland
Merrett Survey Limited surveyed 25 square kilometres of Greenland at a resolution of 2.5cm per pixel using a UAV equipped with a high resolution camera to create photogrammetric point clouds, contours, Digital Terrain Models and more. We use the latest technology to deliver stunning results.
If you are looking to source a UAV survey, then contact Merrett Survey Limited. Our geodesy knowledge means that we can provide accurate and detailed mapping. Our drone pilots have worked in many different environments and we can provide the best and most cost effective solutions.
Book Your Free UAV Survey Quote at Merrett Survey Today
With our honed aerial survey methods, latest technology and skilled-set team of engineers, contact us on +44(0)1392 362161 or send us an email to info@merrettsurvey.com to enquire about our successful UAV surveys.
Peter Merrett - Owner & CEO
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