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Is it possible to exclude static meshes from landscape LOD generation (world composition)

Hi,
As the title says, I’m using world compostion and I’m trying to generate LODs for every tiles of my world.
In the past, you had to get a Simplygon licence to merge static meshes into the landscape LOD, so generating LODs was only converting the landscape tile in a static mesh without using the static meshes on this landscape.
Now you don’t need Simplygon, generating LODs doesn’t only convert landscape in static mesh but is building a static mesh by merging all static meshes on this landscape.
The problem is I obviously don’t want my 3000 static meshes on a landscape trying to be merged in a single static mesh because :

  • It takes way too much time
  • It eats so much memory that the editor fill my 32GB of ram, then crash to an out of memory error
  • Who wants to get any small prop to be merged in a distant LOD ? This is useless and add more polygons for nothing.

I looked almost every setting and I can’t find any one to exclude one or all static meshes from the LOD generation and only generating static mesh LOD of the landscape.
Is it possible?
I even tryied to look in the source of the engine but didn’t find anything.

I noticed there’s a “include component for HLOD mesh generation” in details of static meshes but it looks like it’s only for HLOD generation as switching it to off doesn’t change anything.

Help please, I can’t buy 128GB ram and wait 3h on each of the 1500 landscape tile.

Good question. There is also HLOD, which allows specific inclusion/exclusion. Both HLOD and Landscape LOD Proxy is crashing for me in 4.22, it worked in 4.21. Still pretty unstable.

Here they explain how to create Landscape LODs in UE4, they do that on an empty world composition landscape map with just foliage :

https://www.youtube.com/watch?v=YbnGVrpIGEo

Yes this is what we talking about. Now he doesn’t have any mesh in his world so no problem about mesh merging.
My problem is about mesh merging that I don’t want. I want to create only landscape LOD but once you have a single mesh on your landscape (let’s say a house), the process create two meshes, one for your landscape and one for all the meshes on this landscape.

As I said, it was not the case before Epic intergrate Simplygon in the engine as you had to get a licence for mesh merging, so all it did was to convert landscape LOD in a mesh.

Please, I still need help with this

Help please…

At least, is it possible to turn of the Simplygon integration so the landscape LOD creation works like before?

Maybe I will get an answer one day…

Why don’t you just move your meshes to a new level?

Why using world composition then?
World composition purpose is breaking a large world in tiles/cells like in The Elder Scrolls games, The Witcher 3, etc and stream them or switch them to LODs (landscape proxys converted to meshes) based on distance.

I’m working on a 64km² map divided into 1600 cells (not that much, the Velen/Novigrad map of The Witcher 3 is 72km² divided in 2116 cells)
Let’s say i’m working on the cell x10y20. I sculpt the landscape of this cell then put on it a large castle with some fences, crates, barrels, etc.
Then when building landscape LODs, all the meshes on this cells will be converted in one big mesh and one another mesh will be created for the landscape tile.

  • I can’t chose to build one mesh LOD for the castle as a “distant LOD” and exclude the small fences, crates, barrels, etc. which are unnecessary and makes the LODs generation process using so much RAM (and time) that it makes the engine crash because you have 300 meshes on this tile.
  • If I place those meshes in a new level, they won’t be streamed in/out with this cell
    Of course, I can place those meshes in a temporary level, then build the cell LODs, then replace all those meshes in this cells but it’s a nightmare when working with 1600 cells.
    There should be a simple switch on meshes to add/exclude them to the cell LODs generation or at least, deactivate the LODs generation of meshes like before Epic added Simplygon to the engine.

I dont know much about LOD, but in the “static mesh” details panel you can choose a LOD group. Can this be usefull in you case?

Use sub levels so you can unload your props mate.

Not using world composition is not a solution to a question about world composition. :confused:

you can still have sub levels lol

I already have world composition sub levels loaded/unloaded based on world composition streaming distance, your solution is to not use them because I ask how I can chose which mesh will be added to the automatic mesh merging or not. Makes no sense…

no you misunderstood me, you sub levels for your props and unload them.

I ran into this issue a while ago, what I ended up doing was an engine change that excluded them if IncludeComponentforHLODMeshGeneration is disabled on the component. If I get the time I’ll post the change I did

That would be really great ! :eek: