UNMANNED AIRCRAFT SYSTEMS
What is an Unmanned Aircraft System (UAS)?
Unmanned aircraft systems, better known as drones, are fixed-wing or copter flying systems that can collect w wide variety of data. In the past, drones were mainly used for government and defense applications, but now they’re so ubiquitous that kids have them as toys. One major user base is land surveyors that collect photography for mapping purposes. Drones are piloted remotely via a ground based controller or by pre-loaded flight plan missions. The more advanced surveyor UAS systems include on-board RTK or PPP GPS collection systems.
Types of Data Collected by UAS
2d Orthomosaic Map
Orthophotos create a perfectly straight down view of the buildings below without any perspective distortion which allows for a more accurate representation.
3d Orthomosaic Map
A 3d orthomosaic map is constructed from both aerial and ground orthomosaic photos. They’re pieced together to create a 3d image.
3d drone models are created with NIDAR and Oblique imagery or photogrammetry. The pilot takes multiple shots of the object and pieces them together using computer software.
Thermography uses infrared radiation imaging to capture thermograms, temperature patterns, that make up the image.
Multispectral mapping captures image data within the electromagnetic spectrum. It captures additional data the eye may not be able to see and can be used for vewing under the earth’s surface.
Lidar Point Cloud
Lidar point systems use a laser, gps, and inertial measurement unit (IMU) to produce an X, Y, and Z value that generates the heights of various ground points.
How Accurate are UAS/Drone Surveys?
Using technologies such as RGB, LiDAR, and Near–infrared spectroscopy (NIRS) , drones can collect thousands of data points a minute on a variety of light bands. This enables surveyors to take highly accurate distance and surface measurements that are then processed using mapping software.
Digital terrain models (DTMs) and Digital Surface Models (DSMs) can create depictions of the real-world that are extremely accurate. But conditions such as cloud cover, winds, varying terrain, and the condition of the camera payload can drastically alter the drone’s accuracy and/or precision.
One of the most dangerous scenarios is non-skilled users operating highly-advanced UAS. While the equipment may be capable of centimeter-level data collection, the present settings and conditions insert blunders or errors into the data, and then the UAS operator warrants data that he/she thinks is precise – but isn’t.
Why use drones while surveying?
Drones can reduce the manpower that’s needed while surveying and speed up the collection of data while in the field. The UAS can improve a surveyors ability to cover more ground during a survey decreasing the time needed to complete it. Some areas that were formally unsafe or inaccessible to foot or ground vehicle traffic are accessible via the air. A UAS can tackle those areas and map them without putting the surveyor in jeopardy.