Blocking volumes vs collision boxes


I am currently converting a CAD model to UE4 and in that regard have a little Q…
The model is quite big so I’ve decided to split up the model and floor plan in smaller pieces.
I want to have the floor plan as a single plane for UV and light map efficiency. When I create a simple plane and add a collision box (UBX_mesh_0xx) it doesn’t work. The “master” mesh have to be a closed cube. So I was thinking just to have the floor as a simple plane (50mx100m divided in smaller pieces, i.e. 5mx10m) and use a blocking volume instead of several collision meshes. But is that a sane approach? Does it hurt performance vs several smaller collision boxes?

Thanks for any advice!


Did you ever find the answer to this?

I myself is currently questioning what would be most optimized(Mobile) between modular building pieces having 1-3 Primitive collisions each or simply a blocking volume.
In my scenario it’s tiles of 400x20x400, simple box collision… Or in other words 55 Blocking Volumes (Taking from one of the levels) VS around 110-160 primitive collisions.

Well, You can just make collision cubes in 3d program. The floor can be a plane, just make cubes that sit below it with tops even.

Name your cubes “UCX_Whatever your floor model name is_01” , 02, 03…

Or just use complex as simple for collision in Unreal and it will use the actual geometry.

for the best lightning resulsts you should have one surface/mesh/lightmap for the floor. if you dont like to build a custom collision or the ones createable in Ued dont work, you can use the “use complex as simple” collision in the statis mesh settings.

Complex as simple degrades performance and uses the material for collision, so don’t.

Create UBX components instead of UCX wherever you can use a simple box - anything that isn’t convex like a wall.

as far as performance goes, you are better off separating on a room by room basis so that entering a different room can unload whatever else is occluded.
you can take that further and separate every wall so long as you don’t approximate the corners but match them exactly.

Wall geometry should be 1 plane with a matching UBX that can actually be slightly bigger. And beware that modularity leads to light map bake seams rather easily. Even with peoper snapping in engine.