Different drones will result in different drone survey accuracy. Businesses and individuals can use basic commercial drones in conjunction with drone mapping software such as DroneDeploy to produce fairly accurate photographic and mapping data.
However, engineers and construction companies often require much higher levels of drone survey accuracy. This is because they need to ensure their projects are successful and meet the brief of their clients. Being just a few centimetres out on a measurement can result in big delays, and are expensive for projects. In these cases it is crucial that the drone survey accuracy is at a high level.
On the contrary, estate agents use survey drones to achieve high-quality photographs to market their properties to buyers. They also use drone surveys to spot issues like roofing damage or damp, which don't require high levels of accuracy.
What Factors Affect Drone Survey Accuracy?
There are two types of drone survey accuracy: relative accuracy (aka local accuracy) and absolute accuracy (aka global accuracy).
Relative accuracy describes the accuracy of the position of different parts of your 3D model in relation to each other. Without a high relative accuracy, businesses can't use the drone mapping software to accurately display information about the site.
Absolute accuracy describes how the site model sits in comparison to the real-world position. The use of ground control checkpoints measured independently using survey instruments is the only way to accurately determine the position of the site globally.
Survey drones use the checkpoints as a reference frame from which points in the site are measured, and as a result, the final drone survey accuracy cannot be higher than the accuracy of the ground control checkpoints.
The accuracy of survey drones varies significantly depending on the type of drone, camera quality, flight height, ground cover, weather conditions and drone mapping software. Many commercial and industrial-grade survey drones can deliver data accuracy to within 2cm. Inexpensive hobby drones sometimes result in an accuracy of only 5m.
The uses for survey drones and the quality of their components will have an impact on the accuracy.
There are three main types of drones used for surveys: fixed-wing drones, single-rotor drones and multi-rotor drones.
Fixed-wing drones, also known as ‘remote piloted aircraft systems’ are survey drones with fixed wings, as the name suggests. This means that they aren’t able to hover in the same spot, and are difficult to launch into the air because they require a runway.
However, fixed-wing drones are very efficient in terms of power usage because they have similar aerodynamics to that of an aeroplane and this means that they have long flight times (90 minutes +). Their inability to hover in the same spot can mean that the accuracy of collected data for input into drone mapping software is not as good as other types of survey drones.
Single-rotor drones more closely resemble helicopters, and are more difficult to fly and land than other types of survey drone. Often businesses need special licensing to operate them, but they’re much better at carrying heavier loads than other drones. Due to the fact that they can carry more heavy-duty camera equipment, single-rotor drones can produce highly accurate data to use in conjunction with drone mapping software.
Multi-rotor drones, in particular quadcopter drones, tend to be the most common type of survey drones. They are able to take off and land vertically, but their poor energy usage means they can usually only fly for around 30 minutes. They can produce high-quality data with the cameras that they carry, but their shorter flight time may pose a problem for larger sites.
It goes without saying that the quality of the camera on the drone is a huge factor in the final drone survey accuracy. Higher resolution cameras will produce higher resolution images and videos, resulting in higher quality data.
Camera quality is measured with pixel resolution. A high pixel resolution means the photographs captured by the drone will be of better quality. It is recommended that a minimum of 12 megapixels should be used for commercial survey drones, with a resolution of 20 megapixels being optimum.
The altitude at which you fly survey drones for a drone survey also has an impact on the drone survey accuracy. The higher you fly, the less accurate the mapping data will be.
While flying closer to the site takes longer and may result in multiple flights to cover a large area, the data collected is significantly more accurate than flying high.
There are constant advancements in the world of geolocation technology and drone mapping software. In recent years, RTK (real-time kinematic) GPS systems have been designed that are compatible with survey drone use. With this system, GPS data is transferred to the drone while it is in flight, improving the accuracy of the data collected.
By keeping systems up-to-date with the latest location technology and drone mapping software, survey drone companies such as HeliDrone Surveys can provide the best data for their clients, whether they require a high local accuracy, high global accuracy or both.
Winds of more than 15mph or very cloudy weather conditions can impact the drone survey accuracy. In addition to this, large buildings can interrupt signals and lead to less accurate or altogether inaccurate data.
A carefully planned flight can usually mitigate the risk of certain conditions reducing the effectiveness of a drone survey, but in some cases a reduction in the quality of aerial photographs and video is inevitable.
Are you looking for a UK drone survey company to assist with your site surveys? Get in touch with HeliDrone Surveys.
