I know that Litchi considers where one takes off to be altitude zero. I want to set up a mission. So I followed my drone to two pastures up from my house, over 2 sets of trees. Hovering just over the tall grass (hay) the monitor read 75 feet (altitude). I landed the drone. Took off again and it reset altitude to zero. Is that what it does? I then ascended to above the trees and it read 115 feet. I assume I need to add the 75 feet (hovering over the grass). The 75 feet being the altitude from my base (outside my garage). So the mission would take me over the two stands of trees then ascend to 75+115=190 feet (to be over the trees) if I set the mission from outside my garage? Am I thinking of this correctly? Is there an easier way? Thanks in advance.