An aerial mapping drone can take off and fly almost anywhere, allowing you to capture data without organizational overhead. When it comes to the accuracy of topographic surveys, there are several factors to consider. The first is the ground sampling distance (GSD) of a drone, which depends on the pixel resolution of the camera. Generally, the more expensive the drone, the higher the resolution of the camera images and the more accurate they will be.
A minimum resolution of 12 megapixels is required, with 20 megapixels being ideal. The resolution of the camera and the altitude at which you fly also greatly affect accuracy. Another important factor is the maximum deviation of the barometer during flight. Most drones use barometric altimeters to calculate their own altitude in relation to the takeoff position, but these can have some deviation depending on the quality of the sensor, changes in air temperature, and other variables.
In a 30-minute flight, this deviation can reach up to 5 m above or below the actual altitude. Orthomosaic and digital surface models created from aerial images taken by drones greatly accelerate and simplify topographic studies for land management and planning. Reconnaissance lines should be aligned parallel to the boundaries of the reconnaissance area to reduce flight duration and minimize reference points and turns. The drone should fly between reference points in a straight line, with an altitude that exceeds any trees or other obstacles in the study area.
To minimize fluctuations between the drone and magnetometer after U-turns, it is recommended to maintain a constant course throughout the topographic grid. A drone study refers to using a UAV to capture aerial data with downward-facing sensors such as RGB or multispectral cameras and LIDAR loads. This data can be used for land management and planning purposes. During a drone study with an RGB camera, the floor is photographed several times from different angles and each image is labeled with coordinates.
To collect high-quality magnetic data, you have to choose a direction so that when it is on reconnaissance lines, the drone does not have to perform energetic vertical maneuvers to follow the terrain.
