Greetings Pilots.  Newbie here, first post, and DJI Mini 2 owner of 3 weeks.  Still flying very cautiously, haven't crashed yet, and having a lot of fun. I have a question regarding how the aircraft determines its altitude/height. I understand it is a baronmetric pressure sensor onboard. It appears that this sensor determines the pressure at launch and uses this as a baseline for determining altitude during flight. I notice when I review flight data that if I fly at the same level, neither ascend nor descend, the height indication in the telemetry remains constant. This is the case regardless of what the landform below the aircraft is doing. Yesterday I overflew an arroyo that was approximately 20 ft deeper that the ground at launch point and the height info remained constant.  Similarly I flew a road that rose approximately 10 ft higher than launch point and the height data remained constant. Am I correct in my understanding? If so I need to rethink how to set the RTH altitude.

Thanks in advance.

Kevin

Except for the limited range VPS sensors, your drone has no way to measure it's height above the ground or any obstacles.
The height displayed on screen is relative to the launch point and that also applies to the RTH height you set.

"Am I correct in my understanding? "

Yes

how do i determine where to set my rth height?

i based it on several factors that are specific to me (in order of importance):
1.the maximum legal height allowed by rules and regulations
2.from the home point, the tallest object in the area
3.the likelihood there is an object over and above my drone when it loses connection

if my drone returns to home, it is 75% chance i commanded, 20% chance i lost the signal, 5% ran out of battery.  it is very rare that anything will be over and above my drone since i almost never fly thru tunnels, under bridges, or in tight spots underneath trees for example.  therefore i feel free to allow my drone to fly as high as possible when returning home.  i don't fly super long distances when the battery is less than 50% so returning to very high altitude to travel home doesn't cost a lot of extra time or battery effort.  if i am in a grid, it is likely that grid height will be set to rth altitude.  to your question, on setting rth height, it's relatively flat where i live and pretty much nothing is greater than 120 feet agl.  i have never applied/received laanc at less than 200 feet.  bottom line, for me, rth is either 400 feet or 200 feet, it's that easy.

Hi there, please note that the 'H' means the height from the Home Point. For more details, please refer to: https://dl.djicdn.com/downloads/ ... _User_Manual-EN.pdf