Hi, I’m an Architect and use UE4 for Rendering and interaction.
Recently I started the project based on ArchiCAD and rhino modeling.
But, when I turned on Distance field shadow and AO, It turned a nightmare.
When I zoom into the facade, some dark spots are drawn on meshes.
Is the scene using a Light Propagation Volume? What are the DFAO and DF shadow settings?
You need to increase your distance field size for those meshes.
If you look at your scene in mesh distance field view, you’ll see the building is basically not there:
Hi, generally two things when you use DFAO:
(1) do not use one sided meshes. If you need to do so and experience those dark spots, then enable two sided mesh distance field generation for those meshes. But of course this will come with a performance impact
(2) if you scale your meshes up too much, then you need to increase your mesh distance field resolution to compensate
Also you need to be somewhat careful how you place your meshes. For example if your wall is not thick enough and you place meshes in the inside directly at the wall, then you might/will see dark spots at the outside.
I’ve read that split meshes work for preventing light / shadow artefacts, especially for walls / doors / ceilings / floors / etc. A split mesh is basically the usual mesh used for a wall or object is split down the narrower width of the mesh. So it’s then two meshes conjoined. It’s similar / same as using a loop cut to subdivide a mesh.
I’m not using Light Propagation Volume. These are my settings.
This is Mesh distancefields view mode. I don’t know how can change my distance field size.
(1)I found information about DFAO, and that said like you. but I checked ‘Two side’ before, It didn’t work. and I think It could make my performance worse. Because my file is based CAD, so many actors in here(20456)
(2)It’s a 3D model for a real building so It’s already has a huge scale 
I didn’t change things about scale. It’s just imported by using datasmith.
I’m afraid of using DFAO on an exterior architecture project… Maybe it’s not for a architecture project I guess
anyway, Thanks a lot!
Can you tell me about ‘Split Meshes’? Now I merge the meshes have the same materials. I’ve read one if a huge scene made with many small meshes, It won’t make right DFAO like my case.
I don’t know it’s right for my problem, I just try to hope it’s a key to fix this:(.
Very dark. This is the first person template in MDF view:
As you can see the cubes are fine, but the walls have a big chunk missing. They would need the MDF size increasing.
You do it in the static mesh editor:
That might be a problem =)
The maximum resolution the mesh distance field can have is 128x128x128. So if the mesh would be too big, this mesh distance field resolution would be too small for it and you could get those black spots. So you could try to break your really big meshes down into several smaller ones (I can’t assure you that this will solve the problem but might be worth a try if you’re out of other ideas).
Splitting meshes is basically how I was referring to what Chrudimer suggested too. Break meshes into smaller meshes. So the big sidewall of the building in the photo given; split it so it’s 3 separate, but aligned meshes. But there’s also splitting the mesh on its narrow side. If it’s only splitting several huge meshes into somewhat smaller ones, then I think it wouldn’t severely impact rendering speed or real-time render and visualizing. The purpose is to get those meshes small enough to increase the DF resolution scale in the mesh editor settings, and to prevent light/shadow leaks by splitting the mesh on its narrow side (similar to splitting a door on its narrow side, not its height or width but its thickness).
I found a similar issue and led to the same direction called ‘dynamic light’
and after I learned all of that I realized that it had to be paid for with expensive rendering calculations.
if u want to manage the simulate with dynamic global illumination
just set lighting in the moveable category
then go to the project settings
and activate;
1 light propagation volume
2 ssgi
3 generate mesh distances
I suggest you read the document related to the things above. if u hv 4.25 u can find them on project setting
restart the engine
and wait
You have to set the mesh distance again on each mesh that has a strange shadow like that. as write on #
You’ll most likely need to tweak the Light Propagation Volume (LPV) settings to remove the shadow artifacts. There’s a video on youtube on how to activate the LPV and what changes remove those shadows, if that’s going to work.
UE4 Tutorial: Light Propagation Volumes
