When it comes to choosing a drone for topography, flight time and range are two of the most important factors to consider. You need to make sure that the drone can fly for a long enough period of time and cover the area required for the survey. Many drone pilots are now taking on mapping projects, but newcomers often struggle with precisely georeferencing images with real-world coordinates. This is where real-time kinematics (RTK) comes in.
With this technique, drone pilots can achieve positioning with an accuracy of centimeters as the UAV receives GNSS corrections during the flight. There are several RTK-ready drones on the market, but having the right aircraft alone does not guarantee survey-level accuracy. Other factors such as mission parameters, environmental conditions, and the number and location of ground control points (GCPs) also play a role in determining accuracy. If you need to achieve a certain level of precision in centimeters, you'll need to think about image resolution, altitude, overlapping images, and GCPs. GCPs are markers arranged over the area to be mapped that act as reference points. Since their location is known, the images taken by your drone can use this information to recalibrate their recorded location.
This leads to greater accuracy and also helps to scale and rotate the map correctly. It's important to remember that a drone can only map what it can see. It is equipped with a 20 MP camera, which is its data collection device. If there are trees or extensive vegetation cover such as shrubs or scrubs in the area, the drone will not be able to accurately map the Earth's surface. In this case, traditional methods of land surveying will be more effective. Using photogrammetry software, aerial images taken by drones can be used to create georeferenced orthomosaics, elevation models, or 3D models of the project area.
These maps can also be used to extract information such as high-precision distances or volumetric measurements. When conducting a drone study with an RGB camera, it's important to ensure that no one approaches the drone during takeoff or landing and that weather conditions remain optimal for the reconnaissance mission. Advances in drone and imaging technologies mean that drones are proving to be increasingly valuable for applications such as surveying, mining, construction and agriculture. Reconnaissance drones generate high-resolution orthomosaics and detailed 3D models of areas where low-quality or outdated data is available. However, it's important to remember that a drone is not always the right tool for every job. Fixed-wing drones may be more efficient for aerial reconnaissance work with LiDAR due to their similarities with traditional manned aircraft. Orthomosaic and digital surface models created from aerial images taken by drones greatly accelerate and simplify topographic surveys for land management and planning.