In some cases, it's recommended to change the flight direction to prevent collisions, maintain consistent GSD, avoid missing images, and increase efficiency.
Choosing the most appropriate flight direction involves considering different parameters. The four key factors to consider in order of importance are terrain following, wind direction, picture efficiency, and polygon shape. To change the flight direction, use the slider adjust, or to be more precise click on the box to type the exact degree.
Terrain following (ground clearance)
The most important thing you need to consider when choosing the flight direction is terrain following. We recommend flying perpendicular to the slope like a switchback rather than in its direction. Don't fly straight into the slope! A waveform of the ground elevation in the altitude graph indicates the latter, while a flat ground with steps at the turnarounds would be ideal. Also consider enough space for the turns so that they do not interfere with any objects close by.
WARNING! It is not safe to fly with large humps in the graph, because this indicates that you are flying in the wrong direction! The path will show in red if there are portions below your safe ground clearance. Below you see the graph image on top, showing the wrong way, versus the bottom ideal path.
In case of notable wind, we strongly advise you to fly orthogonally to the wind direction. Try to avoid strong tailwinds and headwinds to avoid missing images. To improve output reconstruction, especially for homogeneous areas, it is not recommended to fly aligned with linear structures (such as roads or cultivated fields). This reduces the number of similar-looking images.
Note: When planning a mission in conditions with high winds, we recommend considering the drone in the midst of turns. To learn more about this, please read Flying in windy conditions
In order to create a good map, it's important to choose the correct overlap. You always want to fly slightly more than the defined area in order to get enough overlap on the edge of the polygon. Be cautious: if the mission has sweeps outside of the drawn polygon, the drone will take pictures throughout the entire sweep, wasting both flight and post-processing time capturing pictures of an undesired area. By splitting the areas up, we can reduce unnecessary images.
When drawing polygons or importing KML files, flying parallel to the longest edge decreases the number of turns, which leads to longer flight duration. With this strategy, the maximal coverage can be reached. For example, when planning a corridor, try to fly the long way to reduce turns, but first take into consideration the elevation change. If there is heavy elevation change, you will need to break the corridor up into chunks or fly perpendicular. Safety clearances are more important than covering more area.