Ideally, when possible, the drone should maintain more or less the same absolute altitude on the reconnaissance lines. Reconnaissance drones generate high-resolution orthomosaics and detailed 3D models of areas where low-quality, outdated or even nonexistent data is available. To reduce the duration of the flight and minimize the number of reference points and turns, reconnaissance lines can be aligned parallel to the boundaries of the reconnaissance area. A drone survey refers to the use of an unmanned aerial vehicle (UAV), or drone, to capture aerial data with downward-facing sensors, such as RGB or multispectral cameras and LIDAR loads.
Aerial images taken by drones greatly accelerate and simplify topographic studies for land management and planning. Orthomosaic and digital surface models created from aerial images taken by the WingtraOne topographic and cartographic drone can be used for a variety of purposes. If there are any problems with the equipment (low battery, loss of RC signal, depending on the type and configuration of the drone), or if the operator presses the “Home” button on the remote control, the drone will rise to this altitude before flying back to its original location. This is especially important for magnetic studies, as the study area can be quite large and may require several flights to complete. During a drone survey with an RGB camera, the ground is photographed several times from different angles and each image is labeled with coordinates.
Anemoment manufactures a lightweight 3D ultrasonic anemometer for atmospheric monitoring, while Geometrics provides a UAS-compatible magnetometer, MagArrow, which allows drones to collect geophysical data for magnetic studies. Before beginning a 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. The UGC will add additional short segments at the end of each topographic line, but no additional reference points will be added to follow the terrain on longer overpasses or between topographic lines. A drone that makes a U-turn at the end of a reconnaissance line at this speed will cause a pendulum movement of the magnetometer on a tow cable. Altitude is mainly defined by the type of survey and the capabilities of the sensor, or by specific customer requirements for geophysical studies. This configuration helps to minimize noise from drone 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 airflow.