GPS systems are essential for drone mapping, as they allow drones to fly along pre-programmed flight routes, stay within the designated study area, and geographically tag photos as they are captured. The images captured during the mapping contain visual and spatial data that are processed during the rectification of the image. Real-time kinematic satellite navigation (RTK) is a centimeter-accurate technique for obtaining GPS (or any GNSS) data. This technique analyzes the GPS radio signal to calculate this data.
RTK is a great solution as it eliminates the need for ground control points (GCP). Before starting a drone mapping mission, it is important to check that the drone's battery and connected devices, such as tablets, are fully charged and that the memory card in the drone's camera has enough empty space to capture the entire project. Software is also a fundamental part of drone mapping; it processes and combines drone data to create maps and models. Digital elevation models (DEM) are a useful result of drone mapping, providing elevation data for the study area.
A 2D orthomosaic is a top-down map of a topographic site or asset created by joining hundreds or thousands of digital photographs taken by the drone. During a drone study with an RGB camera, the floor is photographed several times from different angles and each image is labeled with coordinates. Aerial images taken by drones greatly accelerate and simplify topographic studies for land management and planning. Orthomosaics and digital surface models created from aerial images taken by drones are ideal for more informal drone mapping missions.
For more complex and professional drone mapping missions, paid software is probably the best option. Reconnaissance drones generate high-resolution orthomosaics and detailed 3D models of areas where low-quality or outdated data is available. A drone study refers to the use of a drone, or unmanned aerial vehicle (UAV), to capture aerial data with downward-facing sensors, such as RGB or multispectral cameras and LIDAR loads. Jim Gorrie, executive director of Brasfield & Gorrie, says that drone mapping has helped create a much more efficient process, while Michael Lambert, director of VDC at Chasco Constructors, believes that cartographic data from drones helps teams make “better informed decisions”.
It covers the basics of drone mapping technology and includes an example of a survey data processing workflow with Pix4D and AgiSoft.