Lightmass problems: artifacts/stains
interpolator
I am having trouble getting Lightmass to create Lightmaps without blotches and stains. Even on 512 or 1024 for each window and on production quality. Is Lightmass supposed to produce so many artifacts? If I look at the generated SimpleLightmap texture and the DirectionalMaxComponent texture? Anyone have some tips?
Replies
The blotches you see is usually either because of inaccurate calculations( not enough photons) or lightmap texture compression.
Once you apply a texture on those assets, you won't notice it at all, but if you still want to have it completely clean you can disable compression ( lightmaps will take much more space) and/or increase the amount of photons cast( longer bake-times)
How?
You can change both in a file called BaseLightmass.ini located in UDK/Engine/Config/
Compression = 'bAllowLightmapCompression=True'. Set this to FALSE if you don't want compression
Photon count = A LOT of different values in that same file. I'm sorry, but I can't go through them all at the moment. But I think most of them should make sense and they have a little bit of commenting int he file.
My advice would be to just leave it alone, both compression and the other values. Lightmass has been tweaked to work in production with the default settings, you just have to texture your assets. But if you really want to, you should know how
Oh, PS
The scale of your world matters. The default lightmass values are setup for Gears of War scale. So make sure you keep to those scales. If you have different scales for some reason, you can tell lightmass by changing the value of World-Properties->Lighmass->Level Scale
Oh PS2: One trick to reduce the compression/noise is to use vertex-baked lightmaps( set resolution of your assets to 0). This only works if your assets have the correct tesselation. I'd say, try it out, I end up using it A LOT.
Ok enough for today, good luck!
@Osman: Thanks for the detailed reply. I know about the Level scale and the Settings in BaseLightMass.ini, but this exponentially increases the render time of the lightmaps. (I could probably use it in the final verion).
When using vertex-baked lighting I would have to add a lot of polygons to my models to evenly divide them. I don't think that't an option. You say you have used it extensively, how did you manage to keep the vertex count down?
And why are the stains and blotches concentrated in a few areas? It should be possible to just blur the maps a bit. Maybe it's better to use lower resolution Lightmaps but bake them with higher settings in BaseLightMass.ini?
- Set everything to vertex baked.
- Do a bake and see how the assets look.
- Good looking models I leave to vertex, bad ones I use lightmaps for( i never really go back to add more vertices, too tedious, but I do
think about it while making the model. Don't be scared to add a few more, I assume you're targetting 'next-gen'?
- I start as low as 32x32 and I up the resolution whenever needed. It usually ends up between 32-128 per asset.
- I add a quick concrete texture to it, to see which areas the blotches are still visible and I try to focus on that area if its an important area.
For my latest completed scene ( on my website ) the lightmaps bake in 1-2 minutes in Production on a decent machine.
I hope this helps, I would really need worry too much if you need to get this done fast, just add textures and it will be gone. But if it's for learning purposes, then I'd say: tweak tweak tweak!