Shadow/light bleeding problem with static meshes I made

Development Rendering
, , , ,
22

Ah, I see. I can answer most of these questions, I believe.

  1. Does your GPU support hardware accelerated ray-tracing? If not, assuming it works at all, it will be doing the ray-tracing via compute shaders, which are far, far slower than the dedicated pipeline, and not all that useable.

  2. What version number are you on? UE5EA’s performance in HWRT is borderline unusable, especially on AMD cards. If you’re not on Preview 1, update your project to it, the performance is superior and genuinely shippable in my experience (I do have an Nvidia card however :).

  3. What you’re seeing is a classic problem with ray-traced shadows and nanite geometry: Ray-tracing doesn’t work with the full-detail nanite geo (they’re working on a patch for this I believe, but it’s a far ways out). What’s happening is that the proxy mesh that nanite generates is casting shadows that don’t match the full-res geo, leading to a lot of self-shadowing artifacts. You can crank up the proxy definition to 100% to avoid this issue, but then it basically defeats the point of Nanite. better yet is to just make the meshes invisible in ray-tracing (look in their details panel), and the problem should be solved.

  4. The way Lumen handles landscapes using SWRT isn’t as robust as HWRT in my trials, and I think the ray offset problem is worse, and swiching to HWRT forces it to actually intersect with the landscape directly, instead of the heightfield it generates.

Potential solution: disable ‘use hardware ray tracing for lumen’, but keep RT shadows on in the editor settings. Set the shadowing method to virtual shadow maps. Disable every mesh in your scene except the shell (s) from casting RT shadows (they’ll just default to VSMs which are perfectly usable).

Results: The landscape will still be using hardware ray-tracing ,which is expensive but far cheaper than having to do that and trace against every mesh in your scene. The shell should be receiving proper world-space shadowing. This is definitely an asymetric use of the RT featureset (disabling it for GI but keeping it for shadowing), but it might solve your problem. Let me know how it goes :slight_smile:

1 Like
23

And Preview V2 just came out today, with a ton of fixes. It might end up sorting some of this out.

24

My card supports Ray Tracing but does not perform very well with it being AMD and no tensor cores; I take on average a 20 fps hit with it enabled.

I’m currently on Preview 2

I tried making them invisible in details to ray tracing but had no effect. I then proceeded to change the nanite materials (not sea shells) to not receive ray tracing. That worked but the shadows seemed “off” you could say. I also didn’t receive any performance improvement which I found strange since the majority of my level is nanite.

I tried as you suggested, keeping ray traced shadows enabled in project settings and hardware off, no change, even use hardware when available, but no change.

I guess I can only wait or go Nvidia next time around. Perhaps RDNA4 AMD will have a solution down the road to ray tracing on a hardware level.

25

I’m sorry nothing appears to be working, I know how frustrating it can be.

That behavior is extremely strange, and since I don’t have an AMD card, I wouldn’t be able to diagnose it well. I have no doubt 5.1 will include all sorts of features and updates, and I wish you the absolute best with your work.

26

Hey cheers to your ventures, projects and work also, thank you so much.