Hi, try to disable contact shadows in your directional light (set their lenght to 0) and see if that fixes that (ofc you will then loose those shadows).
I have no idea what is causing this lighting issue and I’ve seen it before. I have asked people on several occasions what could be causing it and although people keep trying to help I can’t seem to figure out what could possibly be causing this. I have no idea if it’s a setting in the engine, or something to do with my graphics card. I don’t seem to have these problems in any of the games I have played either so I’m assuming it’s a setting in the engine. The shadows are also flickering noticeably. Some of the shadows have obvious lines going through them whereas others just appear to have flickering pixels like noise on an old tv.
I would really appreciate it if someone knew how to fix those shadows…This is the new Rural Australia Package released recently and all I did was add it to a project and load the first example map.
Edit: I wanted to add to this that the trees in the scene have normal shadows, but pretty much everything else appears as seen in the image above. You’ll need to view the links to the pictures and zoom in to actually see the artifacts clearly.
Well I at least know what’s causing it now. However getting rid of the shadows all together doesn’t isn’t going to fix it. I’m trying to figure out how to make the contact shadows as smooth as regular shadows.
So I still haven’t completely figured it out as far as the noise but going to ‘Project Preferences->Rendering->Default Settings’ and changing the Anti-Aliasing method from FXAA to TemporalAA fixed about 80% of it. The flickering completely stopped and the shadows seem a bit more solid…although I am still at a loss as to what exactly is going on and what is causing it.
Contact shadows are a screen space effect (that is also why they fade out at the edge of the screen). So I wouldn’t expect them to be artifact free but they are fairly cheap. The noise is most likely due to it tracing rays to the lightsource, and effects using ray tracing seem to be generally more or less noisy since you don’t want to use too many samples due to performance (no idea though how/whether you can increase the number of samples contact shadows use). From the docs:
Note that the number of samples taken
in the scene depth buffer remain
constant, which means that you’ll see
more noise (artifacts) as you increase
the Contact Shadow’s length.
Basically, a Contact Shadow length of
0.75 generates more noise than a length of 0.1.
The docs page Contact Shadows in Unreal Engine | Unreal Engine 5.3 Documentation
Shadows in UE4 are a patchwork of several different systems, so in the end I guess you need to decide whether the scene with contact shadows looks better than the scene without it.
Thanks, that answers my question. It makes sense then that they would do it that way. Basically it seems for this particular system, hardware is the limiting factor.
BTW - I think there may be some confusion with the answer, as it seems to be suggesting that you are ray tracing, and I don’t see anything in the original post that says you were in ray-tracing mode. Also, it’s confusing to be talking about contact shadows (a screen space method) if you are ray-tracing - this would depend on whether a hybrid method was being used.
Yeah actually I went back and checked and ray tracing wasn’t enabled. Those shadows disappear if I get too close and look a bit noise from close to mid range. beyond that you can’t tell too well that their noisy. I believe specific features utilize ray tracing techniques to perform their functions but I’m not real sure. It’s not that big of a deal, hopefully they can get the bugs worked out of Lumen and make it a bit more performance friendly by the time UE5 is officially released. Right now as it is I have noticed shading artifacts pop up on the landscape material in specific situations. I believe those artifacts have to do with issues directly related to how Lumen works with Runtime Virtual Textures, so maybe it’s a bug they will eventually fix. I should mention I am using UE4 in the above project I was just bringing UE5 and Lumen up because these shading issues aren’t anything new to the Unreal Engine and seem to persist even in the Newest versions.