When planning a drone survey mission, there are many environmental conditions that must be taken into account. The quality of the images produced depends on a combination of ambient conditions, ISO, shutter speed, aperture and white balance. To get the best results, it is necessary to perform several tests to determine the optimal settings. A camera with a high pixel resolution is essential; 12 megapixels is the minimum requirement, with 20 megapixels being ideal.
The resolution of the camera and the altitude at which you fly will affect accuracy. The Universal Ground Control (UGC) will add additional short segments at the end of each topographic line, but no additional reference points will be added for longer overpasses or between topographic lines. If you find yourself in such a situation, you should call the drone back to your house or move away from a reference point to force it to escape from the problem region. This is especially important for magnetic studies, as the study area can be quite large and may require several flights to complete.
To collect high-quality magnetic data, you must choose a direction that does not require the drone to perform energetic vertical maneuvers to follow the terrain. Additionally, you should ensure that no one approaches the drone during takeoff or landing and that the weather conditions remain optimal for the mission. The data collected during the drone survey will be transformed into real-world measurements and distances. There are several RTK-ready drones on the market, but a drone alone does not guarantee survey-level accuracy.
When flying, make sure that the altitude above ground exceeds the height of all trees and other obstacles in your study area. During an aerial photogrammetric study, a drone takes a series of superimposed images with a high-resolution camera. Ideally, when possible, the drone should maintain more or less the same absolute altitude on the reconnaissance lines. This configuration helps to minimize noise from motors and electronics, but it has obvious drawbacks: at inflection points at the end of topographic lines, MagArrow tends to move like a pendulum and it is necessary to use fairly large oversteps in recognition lines to allow MagArrow to stabilize in the airflow.
Aligning reconnaissance lines parallel to boundaries of recognition area can reduce flight duration and minimize number of reference points and turns.