Questions about Lightmass and LPV lighting?

Development Rendering
1

Hey guys!

I’m here because I have some questions regarding lighting in UE4. As far as I’ve researched UE4 still uses lightmass (SVOGI didn’t make it) for the GI. I have worked before in the UDK (which also used lightmass) and found that all assets need a second UV channel for proper light-shadow baking. No matter how I tried I never managed to do a proper 2nd UV channel and therefore constantly ran into the “Overlapping UV” error and the lighting was always messed up. As far as I’ve seen in the forums this appears to still be a problem in UE4. I saw the part about LPV lighting which eliminates this error, however it is still buggy.

So, here are my questions:

Is there an easier way of getting a correct 2nd UV channel setup other than manually tweaking it? Maybe a plugin for (blender, , etc.)?

How long more or less until the LPV is “production-ready”?

Thanks in advance!

2

You can do lightmaps pretty well as long as you do them manually, there’s nothing that does a very good automatic method.

I don’t think they actually intend for people to use LPV, it certainly isn’t an option for interiors. You can set the size to be smaller so it can have a higher amount of detail, but everything outside of that area won’t get the effect so it’s pretty much useless because of how low detail it is.

3

Have you tried using the UV tool in UE4? It will get “correct” UVs for lightmass, though maybe not the most efficient for getting the best results. But is easier than doing manually if your not very experienced with UV unwrapping.

If you wanna learn UV unwrapping, then google some tutorials on the UV tools in your 3D app. And here’s a link to the UE documents on creating the best UV layouts for lightmass…
https://docs.unrealengine/latest/INT/Engine/Content/Types/StaticMeshes/LightmapUnwrapping/index.html

4

I haven’t yet subscribed to UE4, so I haven’t tried using the UV tool, the only info I’m getting is from these forums and youtube. Thanks for the link, I’ll take a look at it. Didn’t know the LPV was not intended for production, I thought it was a similar tech to what Cryengine was using.

5

In blender it’s very easy to create a 2nd uv channel:

6

The automatic lightmapping tool in UE4 is not very good, and any others I’ve used create too many seams.

7

LPV is still in development from what I understand. You can enable it through config files, but it’s not production ready. Not sure what the ETA on it is, or if they plan on ditching it and exploring other options for realtime GI.