Modular Asset Lighting Problem

that is looking really nice now, good job!!

Great screenshots! Once you get to a point showing off more feel free to post in the WIP section as well! We definitely love seeing what everyone is working on in.

Keep up the great work!


I used it because I saw a dude do it on youtube. :slight_smile:

@Tim I will be announcing my game in the WIP section soon! :smiley:

Thanks again everyone! :slight_smile:

You’re the man, Tom! It was super hard to find this info, and I am sure 99% of UE4 users are suffering from this problem. Is there any way to make it more public? Maybe a front page or something?

Not really. I could take the info and see if I can get a Wiki page up with it. I agree this would be really helpful and I’ve usually posted this forums post for others when they’re having issues.

I’ll see if I can get a page up before the end of the month. I would want to tweak some things and make some proper examples if I were going to do it though and that’s the most time consuming part. :slight_smile:


I just started with lighting and wonder if you still need to make lightmaps? SO far i did not made any lightmaps, at least not myself or that i know of. I got blurry shadows black models sometimes… will try teh suggested lighting settings from above, i have hundreds of UV’s…

You only need to use lightmaps if you are using lightmass (baked lighting).
The easiest replacement being LPV which can be enabled pretty easily, but doesn’t give results anywhere near lightmass.
There’s also VXGI and DFGI from Nvidia and Epic’s (promoted/master) githubs respectively.

I find it a bit strange that i have to go to github to get an extra build, because i want some good lights. Btw, how do i enable LPV? I currently have a scene with a stationary skylight and a directional light.

If you have not assigned manually second channel then UE4 automatically created second UV channel for Lightmass based on your first UV channel. To fight blurriness just increase resolution of Lightmass map for particular object. Bigger objects need bigger resolution, smaller - lower

Thanks! Will test this in a bit.

I should have mentioned that both VXGI and DFGI are works in progress, not finished.
DFGI should be included in 4.8, but you’ll have to enable it in a similar way to LPV probably.

LPV might create as many problems as it fixes but I use it anyway because I don’t have nearly enough RAM to build anything that I’m working on with lightmass.

Now add at ur scene directional light, rebuild and enjoy.

Question related to the UV grid setting.

Let’s say you use this to setup your UV unwrap. Can you then, later on in Unreal, use a lightmap resolution higher than 64px, lets say 512px ?
Will the resulting lightmap still benefit from the 64px UV grid I used earlier ?

The grid size of a 512px map would be so small I can’t even set this up in 3ds Max. (1 / 512 = 0.001953125 )


I am working on a modular building asset as well, but we use only realtime lighting. We also had issues with shadow seams along the edges!!

Make sure you snap the mesh to grid in your 3d programm (maya/blender) and also make sure to snap your meshes to grid in the editor.

1.) select your mesh
2.) right click -> transform -> snap origin to grid

Looks like the transform degenerates when you drag the objects around. In our case a small offset of 0.03 did cause visual seams caused by the direct light (you can switch off all light influences seperately)

I hope that helps sp

I’m a bit confused. It sounds Like you are saying the exact opposite of what the majority of people are saying in this thread and elsewhere…

Well being an old school map maker the “art” that is ideal lighting is tricky as the first thing one needs to realize, and to steal a line from a move, is that lights in 3d space do not exist and as the lighting artist one is in fact painting with lights with in a 3d perspective so the same tricks a 2d artist would paint using brushes in Photoshop which translates to the same ideals considering that “static” lighting is baked into the texture. So rule of thumb is use as many light emitters to create the effect your looking for instead of being conservative base on the idea that performance will be effected.

To toss a few ideas into the mix I did up some lighting theory as to my approach to getting the light effect that I’m looking for.


As an opinion I think the problem you are having in getting proper lighting behavior your trying to hard to get a single light to do it all.

I have an environment I’ve been working on for a bit and did have uv light seams pop up and the Lightmass World Settings fixed it, initially. I’ve checked light maps and they are set properly. They were not before and should have checked that before going as far as I had but lesson learned. I’m starting to place lighting to set the mood for the environment and I adjust the one point light I have placed into a fixture and I now have a disco ball like effect going on in the room. No clue why. Seams are popping through again as well. Just on the ceiling. I have my own thread going without much traction. I’m unsure of what’s going on and how to fix it.

you need to offset your lightmaps UV shells by 0.5 pixel as when UE packs things together what you have unwrapped to align with pixels will be offseted and will introduce bleeding on edge, duno if this is still the case but it used to work like this for quite the time.

*Right-click “Creating single static mesh from selected actors” and replacing the single ones could be a workaround *(it happened again)

“Force Volumetric Lightmap” in the object settings might help

hey i fixed the lights problem, i made a video about that, check it out : HOW TO FIX INDIRECT LIGHTS FOR MODULAR ASSETS | UE4 - YouTube