Lighting issue with modular wall pieces

nordahl154

Anyone have any idea why this particular piece is shaded slightly darker than anything around it?
You can see the same type of piece is having the same issue off in the very left of this image.
As far as I know the object was identically mapped (abundant room in the lightmap UV), baked, textured, etc. so maybe it's a lighting issue?
The scene is being lit by a skylight, a directional light, and bounce cards in every window.

Obscura

Are you baking on preview, or production?

nordahl154

Production.
Been a while since I've visited Polycount, good to still see you around 

Obscura

Try setting the static lighting level scale to something low like 0.1, and increase indirect lighting quality to at least 2. You can also try playing with the indirect lighting smoothness.

Also, check this thread:
https://forums.unrealengine.com/showthread.php?46269-Modular-Asset-Lighting-Problem

McGreed

Are you sure that the smoothing groups for each wall sides of the corner isn't the same as the inner part of the corner?

akaChris

This is a widely known issue with Lightmass with varying lighting results per object (per cpu core and object). You can go brute force with the quality settings as Obscura suggested but in larger levels that can easily push your rendering on a single machine from a couple of hours to days. The other way around would be to use the merge actors tool for everything that should be seamlessly connected. Or export seamless objects in the first place. It's a big hazzle working with modular pieces but unfortunately Epic doesn't have a good answer for other than putting in manual labor to avoid these issues.

musashidan

4.13 added cached shadow maps for stationary lights that behave like dynamic lights so this could be a step towards avoiding the pain that is lightmaps. I haven't tried it yet but it might be worth looking into.

akaChris

musashidan said:

4.13 added cached shadow maps for stationary lights that behave like dynamic lights so this could be a step towards avoiding the pain that is lightmaps. I haven't tried it yet but it might be worth looking into.

if you mean the new shadow map caching, this is only a performance optimization for moveable lights to not update the shadow map each frame (since you can reuse the information from before if nothing has changed) and tbh this is an optimization that should have been in there a long time ago.
Unfortunately it won't do anything for better ambient lighting/Gi. So the only alternative to lightmass atm is VXGi (very hard to optimize to be usable for actual games on actual reasonable target hardware) or as Epic itself pointed out: Using Enlighten (by either having a game that creates revenue above 1 Mill or by switching to Unity :P)

cptSwing

Enlighten is a nightmare, I don't recommend switching to Unity just for the lightmap baking..

Quack!

This is a problem that I encountered when doing some research for our new game.
The simple solution is to combine the meshes using Windows>DeveloperTools>Merge Actors in Unreal. For some reason, even if the meshes are coincident, unreal will fail at creating a proper lightmap across two separate components.
You can also combine them in a 3D package, but that defeats the purpose of modularity.

Rurouni Strife

This is good to know. I was going to ask about the light map UVs on that specific asset. Learned my new thing for the day.