Boy .. that's a complicated questionOk after thinking about it im either learning something today or everyone is lol. I didnt know the recorded RTH position took in consideration of ground level. I mean I know it has to know the the ground level in order to climb to the height you have it set at but I guess I assumed that was 2 seperate things. I assumed that GPS locations was just longitude and and latitude. Ive never heard of GPS being a 3 position thing. I thought it just added in your start off ground level to the GPS coordinates. Because if that were the case that its a 3 part coordinate then why wouldn't it tell you the 3rd part of ground level when you use "find my drone" it only gives you lat and long. I had my drone stuck in a tree once and it doesnt say whether its on the ground or 50 ft in the air off from home point. Because that would come in handy if find my drone did do that. You'd know if you should be looking on the ground or up in a tree and I feel if GPS had that ability it should certainly let you utilize wouldnt you think? Why would purposesly leave that out of the equation. I just assumed it used the the ground level at first to rise to the altitude you set it at then changed over to GPS location to get it above HP and then just started to decend until the sensors picked up ground level no matter how far it was or close it was. That would also explain why it doesnt take into consideration of height when determining if you're far enough from HP to activate RTH. What is it 30 meters away from home point correct? If it took in consideration of your ground point height then If you were 31 meters up youre technically more than 30 meters away from HP. Im thinking it only knows ground point to go to preset altitude for RTH only using how far the it has calculated your upward rise from zero when you started the flight. Which would also explain why you can reset HP at anytime during your flight and it doesn't need to calculate ground level. When you reset HP during flight you arent giving it a height just long and lat. You move the image 2d not 3d. Am I right here or have I had to much to drink tonight lol
It made my head hurt.
I'll try to simplify the answer.
1. GPS is a three dimensional thing
2. DJI drones use GPS for horizontal position (2D) and use the barometric sensor in the IMU for height.
3. The recorded home point has no height, it's just lat & long coordinates.
4. Find my drone is a blunt instrument of only limited value.
If you investigate the actual flight data for a drone lost in a tree, you get the GPS location and the height data
And in case it helps understand ..
The zero height is separate from the home point.
The zero height is established on powering up while the home point isn't recorded until later when the drone gets good GPS location data.