It would need a centralized "sea level". I'm sure while exploring you'd see and get used to the varying height if the information was presented, and because of the various ground height it wouldn't work to judge tower height on the ground, that's kinda the issue I'm having I can have a marker on the bottom of the tower to see how tall I'm building relative to the ground I'm building on, but because of the different terrain height I sometimes build ziplines that are almost flat when I'm expecting a quicker ride. Just something to think about