Understanding aerial mapping with the eBee RTK
Activate the 3D mission planning feature by selecting the ‘Use elevation data to
set absolute waypointaltitudes’ parameterin the ‘Mission Planning’tab. Elevation
data is used to adjust every mission waypoint altitude as follows:
1. The flight planner uses elevation data to find the maximal terrain elevation
under the current waypoint, the previous waypoint and the flight line that
connects the two.
2. This maximum value is increased by the target altitude value, and the result
is set as the altitude of the current waypoint.
The altitude of every waypoint can always be manually adjusted in the Mission
Waypoints tab. By default, the ‘Change altitude’ parameter for the first mission
waypoint is set to ‘Keep highest’. For all other mission waypoints the ‘Change al-
titude’ parameter is set to ‘Before transit’ so that the drone climbs or descends to
the altitude of the next waypoint (and thus the next flight line) before transiting
and taking pictures.
It is important to understand that even if each flight line can have a different al-
titude, the altitude is constant along a given flight line. If the terrain altitude is
uneven along a flight line, the resulting imagery will have varying ground resolu-
tion and overlap. When the mission planner computes the altitudes of flight lines
it tries to ensure that the required amount of overlap is achieved, possibly lead-
ing to a lower ground resolution in some areas. During flight planning the range
of ground resolution computed by the mission planner is displayed. For optimal
results, it is best to set the orientation of the flight lines as parallel as possible to
the terrain’s contour lines.
One way to increase the resolution and accuracy of the elevation data is to fly a
first mission at high altitude and then create a dataset using Postflight Terra 3D.
You can then automatically import the data into eMotion by selecting ‘Send DSM
to eMotion’ from the ‘Process’ menu within Postflight Terra 3D. The dataset can
then be enabled using the menu in the Toolbar. eMotion will use this custom
dataset (wherever it is available) to set waypoint altitudes instead of its default
Improved SRTM elevation data.
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