1 Determine Aerial Survey Scope
Most of the basemap data of route planning software (ground station) come from Google Maps. Before planning the route, it is necessary to determine the flight scope of the project in Google Earth, understand the landform of the survey area, and make reasonable division of flight sorties, optimize the flight plan, improve the operation efficiency and avoid collision accidents.
2 Determine the Flight Height
Before operation, you should know the topography and landform of the survey area, judge the height of the building in the survey area, and plan the flight height on the premise of safe flight. If there is a precision requirement, the relative aviation height should be calculated according to the ground resolution.
3 Overlap Confirmation
Overlap rate refers to the overlapping part between two photos. Overlap rate is divided into side overlap rate and heading overlap rate.
Side overlap rate. In aerial photography, there is the same ground image part on the adjacent photo taken along two adjacent routes. The overlap between two adjacent navigation zones is called side overlap. (In short, it is the overlapping part of the photo between the line and the line)
Heading overlap rate, because adjacent photos are taken from different positions in the air, the overlapping parts are the same ground, but the images are not exactly the same. The ratio of the part along forward overlap to the length of the image, called forward overlap degrees, is expressed as a percentage. (In short, it is the same line, the overlapping part between the photo and the photo)
▲ discrimination of side overlap rate and heading overlap rate
In actual work, the overlap we set is generally: heading 80% and side 70%. According to the texture conditions in different environments, it can be appropriately increased or decreased.
4 Check the Weather Conditions
Before unmanned aerial vehicle aerial survey, you should master the current weather conditions and observe the thickness of clouds, light intensity and air visibility.
The ground shadow is the smallest at noon. In the two periods from sunrise to about 9 am and from about 3 pm to sunset, the light intensity is weak and the solar altitude angle is too large, and some measurement areas may encounter smog. These situations may lead to poor matching accuracy, fuzzy texture and low brightness of the collected buildings, which will ultimately affect the modeling effect and seriously affect the visual perception.
5 Use steps of ground station
1) open the ground station software, register an account and log in
2) planning route: the computer of the ground station requires networking. Open the ground station and click planning to start planning the route and save the route to the cloud.
6 under normal circumstances, ideal route design generally has the following characteristics
① The shape of the measuring area is regular, and the heading is basically in one direction;
② the heading height is the same;
③ the ground overlap rate is generally: forward overlap 80% and 75% side overlap;
④ there are no difficult landforms in the survey area, such as forests, snow, Waters, etc., because the photos cannot be matched well under the coverage of these landforms.
