Originally Posted by
DaveReidUK
The software constrains the height AGL? How does that work in practice?
If the drone is using GNSS height, that implies it must have access to a terrain model to derive height AGL.
If it's using baro height, the same applies, with the added complication that the drone/controller needs to know the QNH.
Both sound a bit unlikely.
It's simpler than that. On power-up they automatically define "here" as the "base" waypoint. The altitude of "here" is defines as zero AGL, and everything is relative to that.
And before people get too fixated with the idea that a small number of commercial ready-to-go drones will control the market - have a look at websites like Hobbyking, where brew-your-own stuff (including control boards) are available for peanuts with websites full of "how to2 pages and videos to show all but the most numpteous how to create your own multicopter with your own tailored FCS software.
PDR