Multi-battery Altitude


I’d like to clarify a couple of related questions:

  1. Is altitude above the point the UAV takes off, or is switched on? Say I switched it on, then decided to move a little before launch, which also incurred a change of elevation. Where’s zero?

  2. Doing multi-battery flights, I assume I can launch from different points, particularly if I was doing a long linear area. What happens when the second launch point is at a different elevation? Perhaps it needs to be launched from the same point as it landed with the previous battery? Or the original launch point (hope not!)? Or does it not matter that the drone will be shooting from a different altitude? Or maybe the drone must always return to the DD launch point, i.e. I cannot manually fly after shooting’s finished? A lot of possibilities!