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UE4 lightmass issues

Development Discussion Rendering
#1

Hello guys.

Is there any neat guide for creating 3D assets that are ready to use for lightmass settings in UE4. All guides and tutorials and find, already has 3D assets, and focus more on explaining the lightmass settings within UE4, and not the actual assets. I’ve followed some of these guides, but my baked lighting looks terrible, even though I keep changing the lightmass settings and bake again. I can easily find guides on creating your own lightmap UV’s, but when I let UE4 generate the lightmap UV’s for me, they look fine.

This is the results I’m getting when baking at production quality:

tmp.JPG
tmp.JPG1173×520 121 KB

And this is the lightmap UV generated by UE4, for the racks

tmp2.JPG
tmp2.JPG745×740 117 KB

#2

Is one of the concerns that it’s all so bright? I notice the shelves / racks have a gradient going from dark at the edges to light in the middle, and it’s not a radial gradient. Do you really think it is due to UVs or light settings, or material setup?

I have gotten curvy shadows for sharp cornered cubes when setting the Shadow Filter Sharpen value to above 0. I’m still trying to understand how to get sharp corner shadows with directional and skylight settings. I’ve turned off auto exposure, set objects and directional & skylight to stationary, all meshes have default grey material, and lightmass importance volume surrounds the lit geometry with no overlap. Barely anything except SSR enabled in the Post Process. At source angles of 0.5 and 2, the shadows of meshes are the same, blurry at edges and corners. The only other thing I can think of that’s causing it is CSM and DFS settings (Cascaded Shadow Maps and Distance Field Shadowing), but I don’t know how. A few basic and semi-advanced guides would be preferable to near-constant tweaking and rebuilding.

#3

Nono. I’m not at all concerned about the brightness, that’s just m,e playing around with difference settings to find my “mood” :slight_smile:

One of my concerns is the gradient on the shelves, yes. I don’t know if it’s due to the UV’s, the light settings or the material. I have absolutely no clue, hence this post :slight_smile:

#4

I’m not an expert in lightmap (I’m having troubles with that with my modular walls, just want to throw my computer by the window x) ), but your lightmap UV isn’t really good. You need some space between the different island to have a proper lightmap, or else light and shadows will bleed on the other islands. Letting UE do your lightmaps might not always be the best idea, sadly ^^

#5

Yeah, there will be light map leaking between the UVs that are so close together.

When you generate lightmap UVs in the engine (which is totally a reasonable thing to do!) you get to set “light map minimum resolution” which determines the padding between the charts. The HIGHER the “min resolution,” the LESS padding there is in UV space – this makes sense if you think about it; when the light map is bigger, the same number of padding pixels will take up less UV space. I usually crank it up to 256 or so.

It’s usually also always better to make UV charts as well connected as possible, while still nicely packing the available texture space. Generating one chart with four rectangles for a strut in the shelf, is going to be better than generating four separate charts, one for each side of the strut. In 3ds Max, this would be the “cylindrical” mapping preferred over the “box” mapping; I’m sure whatever tool you use has similar choices.