Scene editor uses lat, long, alt, heading etc for placing objects. This is the way it is stored in scene xml file.
When you want to create a complex scene with many objects in an external 3d software, and then import it in-sim, this makes things super complex.
I can only think of methods like this, (which i haven’t tried) and for height you should also take into account the earths curvature.
On the other hand, if we could only place a single object in the sim, and have all other grouped (child objects) be positioned in xyz relative to this parent object, then everything would be much much easier.
Am I missing something? Maybe Asobo has an internal tool that simplifies this? Any thoughts?
An example use case would be a road barrier (3m long) that must be repeated (instanced) hundreds of times along a 2km road!
thanks
To make things even more complicated, and actually making it impossible to manually edit the scene xml (to create a scene exporter), the altitude is working like this:
When in the scene editor, the values you see and insert in the Gizmo window are values relative to alt 0, but in the xml file, the values are stored relative to the actual ground level at this point!
So if the ground has an altitude of 100m, and a box is placed 1m above it, the gizmo will show 101, but the xml will have a value of 1.
Of course there is no way to know the exact ground alt in-sim, in order to create a scene xml externally.
This is very very limiting, and confusing also.
Ok for the altitude problem I mentioned, I found the solution.
In the scene XML for every object there is an attribute altitudeIsAgl.
By default this has the value TRUE. It seems that there is no way to edit this from the UI.
When I made this FALSE the object stopped following the ground!
This is great 
This is starting to feel like a diary here, but i’ll go on
I started creating a tool to help with large scenes and many objects, with xy to lat/long conversion and alt compensation for the curvature.
I encountered some accuracy issues (as expected).
Let’s focus on altitude for a bit.
I use altitudeIsAgl=FALSE for all objects, so all of them start counting from 0 level (Offset to ground field in object properties).
Then I inserted a simple box which is 6km in x axis (as a maximum accuracy test) with the origin at the beginning. Then I tried to align a cube at the end of it.
So this is a scenario tha you have these objects at the same height in an external editor (curvature agnostic) and you want the same alignment in-sim.
The 6km object sits at 10m offset. For the small cube to align, I have to input offset 13.728529m.
So for a 6km distance, the drop is 3.728 meters.
But based on this: Eight Inches per Miles squared Formula Derivation
and this http://earthcurvature.com/
the drop should be 2.825.
This is almost 1m difference which seems huge.
How can this be explained?
