Very slow Lightning build

Hey there,

I’ve been working on a map for 3 days now, it’s still quite small. After i did a small cave, around 30-40 meshes placed i tried to build lightning but that took very long just for those meshes(all rocks and some foliage). This alone to get 5% took over 3mins. And since i had to go i stopped building it.

However now my engine is starting to lag really much when i look at the unbuilt lightning. (Map is now a bit bigger than just the cave) However, i have a GTX 670 FTW 4GB edition, which shouldn’t make me lagg.

Now i had around 400 objects i needed to build the lightning for. So i took my time just launched the building of the light and it took around 15-20mins. Now my engine runs smooth without any lagg what so ever. However i still have some bugs. When doing the building i got lots of errors on my grass made in speedtree.
I’ll post part of it but it’s basically constantly the same message

The grass also looks black partially.


does anybody know why this is happening? The slow build time and the grass that is very black? Also- And sorry for all the questions.

The shadow of my tree, is very black. When i stand in the shadow i see 0 light passing through and i’m just blinded when i’m in it.


Does anybody have an idea? All trees and foliage are made in speedtree.

With kind regards,

Full pc spec:
*GTX 670 FTW 4GB Edition
*Intel I7 3770K 3.5Ghz(Watercooled)
*SSD 120gb
*16GB RAM (Not too sure which one)
*Motherboard: MSI Z77A-G45

As addition to the above post i found out now after the lightbuild that i have all these weird lines i can’t get away, even after sculpting it.

How do i delete these?

After trying something out with a “skylight” I managed to fix all 3 errors that are above. Just posting this here in case someone has the same issue :slight_smile: However the errorlog is still the same :slight_smile:

So… what did u do??

So, i just happened to see this post while searching for other lighting issues, and though it is old, nevertheless for the people that may find it through google:

  1. LightMAP UVs shouldnt overlap, since this may produce shadowing artifacts. Right now there is the option on import of the mesh to automatically generate Lightmap UVs (which is good enough most of the time).

  2. Slow Lighting build times are often related to not having a rather small LightMassImportanceVolume set. Just set it to enclose your area where the player can roam, and where you need the most detailed lighting. This shouldnt generally encompass your whole level

  3. Often enough with Foliage there is the problem that it doesnt work really good with static-lighting only. This produces really dark shadowing, whereas with a dynamic skylight/directional light everything looks perfect. IF you need static lighting only, you can open your static mesh, go to the lighting/lightmass setting and raise “diffuse boost” (which makes the mesh receive more lighting from static lights) to a value that is acceptable for you (start with 2.0 and go down as needed).

Edit: oh my, just saw the date on the post. Well, necropost ftw :wink:


1 Like

you helped me , even its old