The use of drones for inspections has become increasingly popular in recent years, as they offer a cost-effective and efficient way to gather data. But how accurate is this data? The accuracy of drone inspections depends on a variety of factors, such as the type of drone, the quality of the camera, the height of the flight, the ground cover, and the drone mapping software. Commercial reconnaissance drones can provide data accuracy of between 0.5 cm and 2 cm, while other drones can only have an accuracy of 5 m. Relative accuracy is often sufficient for projects such as taking small-scale measurements, visually inspecting progress on construction sites, and monitoring the condition of crops in the fields.
Kelsey Martin from Martin Remote Sensing recently compared the volume calculations of a reserve she made with a map of drones with those that were made with the same reserve using traditional terrestrial GPS measurements. He discovered that the volume calculation performed with drones was 0.6% accurate of GPS measurements. This case demonstrates that relative precision is more than sufficient to calculate the volume of a reserve. GSD (Ground Sampling Distance) refers to the number of pixels per centimeter of your data.
The higher the number of pixels per centimeter, the higher the relative accuracy of the map. WingtraOne drone consistently achieved absolute horizontal accuracy of up to 1 cm (0.4 inches) in 23 flights. The term “survey grade accuracy” (sometimes referred to as GIS grade accuracy) has no absolute definition, but it generally involves an absolute accuracy of 10 cm or less. Surveyors would say that technical quality surveys should be accurate to 3 cm or less. The only established method for checking and demonstrating the accuracy of drone cartographic surveys is to use independently measured control points.
Drone maps created with good quality drone equipment, careful flight planning, commercial GPS ground control points and commercial-grade processing software can be accurate to about 2-3 cm horizontally and about 5-6 cm vertically. The RMS error is the final calculation of the accuracy of the results of drone cartographic surveys when all possible sources of error in the model have been taken into account (not just the GSD or GPS error). The absolute accuracy of drone survey data is measured by comparing the observed coordinates (the positions of the control points in the model) with the authorized positions (the coordinates measured independently of the same points on the ground).Drones have revolutionized how construction and earthmoving companies analyze and manage their worksites by providing accurate and reliable topographic data. It's great to see useful information available for free and will become more important as more industries adopt drone topography and mapping.
With good quality drone equipment, careful flight planning, commercial GPS ground control points and commercial-grade processing software, drones can provide accurate data for a variety of projects.