The takeoff point will be where ever you arm the UAV and launch, so it’s dynamic.
It’s important to be aware of where the 1st waypoint is in relation to setting up on the ground and arming. Watch out that you’re not in between the craft and the first waypoint or it will attack you. Try to set your first waypoint at some height and roughly straight above where you expect to launch. That way the craft will fly straight up with minimal sideways travel. I wouldn’t worry about setting a takeoff point.
In your mission you can put a RTL instead of a Land waypoint and the UAV will return to the launch point (obviously) instead of landing at a pre-designated waypoint - if that’s what is desired.
You can start a mission two ways:
- Arm and take off as per normal using a normal flight mode, once happy with performance and stability switch to Auto mode
- Switch to Auto mode on the ground, Arm and give some throttle-up to initiate take off
- Always watch and be prepared to switch back to another flight mode if something goes wrong
Probably always a good idea to Arm and fly for a minute or two in your normal flight modes first to make sure everything is working OK - check that a GPS enabled flight mode like Loiter works before trying Auto. Then you can land, disarm and start over in Auto mode if the idea is to have an autonomous launch.
If you’re using spline waypoints set the first waypoint (at least) as a standard waypoint - then you know exactly where in space that will be. Probably even set your last waypoint as a standard waypoint too. Spline waypoints give a “3D” path so the craft may fly in a curve higher or lower (or further off track) than what you expect in order to reach the next spline waypoint.