We are currently tracking down some strange issue with the LODs on our AI airplanes. Since they are not yet converted to native MSFS2024 I will place the bug-report in the 2020-Section, but we see the same behavior on 2024 as well. It seems that the Sim is “culling” away some parts of the model to early and is ignoring the defined LODs.
Our Models have a set of 5 LODs per model to be according to the SDK recommendations.
As you can see on the images in LOD0-3 the Nose-Wheels are part of the model and only in LOD4 the wheels are removed. Our understanding is that those wheels should be visible as long as LOD0-3 are loaded.
Seems the Sim “culls” them earier causing a strange look of a “floating” airplane at a relative short distance:
Each part/mesh of a model is evaluated by the sim as a completely independent object.
[…] objects which are separate from the main fuselage mesh like the gear, flaps, antennas, and whatever else is small enough to be deemed to not be visible beyond a certain point.
What we have tried so far as workarounds:
[…] tried separating the gear and adding them back to the model as attachments, and that didn’t work either. They were culled at the same distance as when they were exported with the entire model.
Jay (our main model-developer) came up with an idea
An idea I had for a possible solution would be for meshes in a hierarchy to inherit the bounding box of the largest mesh within that hierarchy. Instead of meshes like the landing gear, flaps, emissive mesh lights, etc. being evaluated independently and culled due to their small size, applying the bounding box of the largest object/fuselage to them would function similarly to the invisible cube workaround while preventing the smaller objects from being culled. Of course, this solution would need to be implemented by Asobo and I’m unsure of the impact it would have on performance. There would also need to be some sort of filter so that it only affects SimObjects since applying the same concept to scenery would definitely have a negative performance impact.
→ Would that be something to think about?
In our tests we have seen this “culling” on the default A320 as well, so we think there is nothing at the moment we can do on our end?
I think that workaround would be problematic for cabin item attachments in airliners for example. You want those distant ones to be lower LoD when you’re in the flight deck for performance reasons.
What is stopping you from using the invisible cube/plane method to stop the small objects from being culled? Lots of the default 2024 aircraft use it so i assume it still works.
