Best way for dealing with 400+ small meshes and building light for them


I have a big room with more than 400 meshes, they are set to static and using a lightmap resolution of 64 each one. I’m afraid building light for them crashes UE so, what is the best way for getting this to work? Imagine something similar to a shop with shelves.
Would it be better to set them to movable? Or would it take longer? I’m really lost at this point.

Thanks in advance!

My scene has 838 static meshes with lightmaps resolution ranging from 128 to 2048 and lightmass doesn’t crash :slight_smile: You got ram? I have 16.

Yes, I have 32. But since the last built the time increased a lot and I blame it to these meshes. It almost take 1 hour to get to 2%! At least it ends around 3-4 hours.

Thanks for clearing it up, I thought I was making it the wrong way.

If you have high quality settings it’s normal. My scene takes 5-6 hours at the moment. It can literally stick to 0% for a while before kicking in!

Do you have a lightmass importance volume in the level? How many and what kind of light sources do you have? And as heartlessphil mentioned what are your lightmass settings?

When you set your meshes to moveable, they will just cast shadows from dynamic or stationary lights :wink:
But you could set your lights to moveable -> then you dont have to build your lights, but it’s not so good for the performance

Thank you for your answers!

Let’s see, I’m using a movable directional light as I want a day-night cycle. The rest of the lights are movable (for turning then on-off) and static.
I’m using planes with spot lights in every window for creating the light all over the interior.

And these are my actual lightmass settings :


I usually change Static Lighting Level Scale down to 0.7 in case it takes too much time.

If you’re using dynamic lighting in your game or even just this level the lighting doesn’t need to be built. This also means that any settings in Lightmass have no effect on your lighting.

If you decide to use any static lighting it’s also good to know that lowering the Static Lighting Level Scale will greatly increase your light builds. Only adjust this setting if you know specifically what you’re trying to achieve and how it can affect your game.

Recently I set setup a basic Wiki Swarm Agent/Lightmass Troubleshooting page for common issues like the “Lightmass Crashed” ones. You can have a look here if you like:

For best practices with any Static Light building its imperative to keep your lightmap resolutions as low as possible for the best experience. Swarm Agent is a very CPU intensive process and will use a lot of RAM while building. I really would only recommend higher than normal lightmaps for Arch Vis type scenes where you’re not as concerned with gameplay over the final render.

Just some thoughts to keep in mind. :wink:

Thank you for your reply Tim,

in fact I’m using it for archviz and I’m still not sure about making it playable yet so I’m not really concerned about fps for the moment.
I have 2 levels, one is using dynamic lighting only (exterior) and the other has dynamic, static lights and all those lightmass settings (interior). Each one of them has its own directional lighting and different settings so, -and knowing this is a semi-related question-, I want to merge both levels, can I keep the original settings for the levels?

I mean, keeping 2 atmospheric fogs, 2 directional suns, 2 skylights, etc. I’m using level streaming but I’m afraid I’m not doing it right as when I load one of the levels into the other one it changes all the lighting settings. Which is the correct way doing this?

Not a good idea to run dual skylights or directional lights. The common practice is to make a master light level and put all you base lighting and sky dome elements into it and you can share the common file with any level you wish to work on.