Hi ! Im trying to get (as much as i can) a precise Ortho projection from data i took with a DJI mini pro 3. I am following the “drone mapping guide” tutorial from reality capture and everything is going great, except for the Z or Altitude coordinate. My model and Projection is geo referenced and the X and Y make sense, but the Z goes as low as -50 meters below sea level. I am using the EPSG : 6622 since im from quebec, and it shouldn’t go lower than 18m elevation.
I have the right coordinate system while im creating the projection, and if i try to switch with other canadian coordinate systems, the Z stay the same.
Also, the most probable thing is that my control points are off, they are pretty much all -50 in the Z coordinate, what should i do to make them accurate with my coordinate system ?
Hi Odikies,
drone data are not so precise in the heights. To get a precise coordinates you should use RTK drone or Ground Control Points with known coordinates (there points have to be measured to get the proper coordinates).
Ho i see, i there any way to edit control points coordinate to fake a new Z value ? (Just to be a bit closer to what i see on other topographic maps)
Also what gear should i use to get the right coordinates using Ground control points, apart from targets .
It is possible. You need to change the control points type from Tie point to Ground control. And there you can set the coordinates.
The XY values can be copied from Actual position and Z can be set as you wish.
For measurements you will need GNSS RTK receiver or total station (surveying measurements).
