I have a requirement to meet … no temporal accumulation.
This means no TAA or TSR, though it would be straightforward. Unreal has several AA solutions … but um … it seems every lighting feature of Unreal is just desperately dependent on temporal accumulation, e.g. it’s noisy as hell unless you finish up with TAA or similar.
What am I missing? Is Unreal simply locked into noisy half-solutions that get cleaned up with temporal blurring?
Not a trolling spicy question, I assume the answer is there, and I am just overlooking it, but so far, not finding a lighting solution, even using a baked static main light that doesn’t produce sparks and noise without TAA
Surface/volumetric lightmaps, distance field shadows, cascaded/regular shadowmaps, reflection captures, planar reflections… none of them do any temporal accumulation. SSAO optionally uses temporal accumulation to amortize the cost but can be disabled and looks basically the same, same for SSR. SSR does have some dithering patterns when used without TAA though.
Megalights and the old RT shadows can be effectively brute forced by raising the sample count but well… it costs a lot and for megalights you’ll need to limit the amount of overlapping lights because it still spreads the samples out over the number of lights affecting the pixel.
I turned off all ray tracing, disabled GI and reflections, baked lights, and I still get a ton of noise in shadows, and transparent things look horrible.
I’ll keep poking at it, if you have a sample somewhere I can look at I can’t find even a sample that is both noise-free and not using TAA/TSR
Alternatively you can just switch to forward shading, since it doesn’t support any of the features that use temporal accumulation anything that is causing noise will be automatically disabled. (except any materials you have created that are reliant on temporal dithering)
Okay so there is a LOT wrong in this scene but
But you can see the noise in the shadows and the sparks on for example the knee of the character
This is just a rendering test nothing more so I have been poking at it and making quite the mess but that is the problem I am always seeing when TAA is not used
As to things I have tried
Disable raytracing everywhere
Forgo GI and Reflections
ShadowMap not Virtual
No post process at all
Simplify the lights … just 1 baked direct light + sky
Everything I try has zero effect on the sparks and the noisy shadows
I gotta be honest I can’t see anything in this, I don’t see anything on the knee… compression was brutal to this video. Honestly might be better to just take a screenshot and circle the areas that are having problems. Or perhaps try to upload it as an attachment here instead of on dropbox.
I will say that if this is a character is based on a metahuman or something made by Epic, they use the DitherTemporalAA node heavily in their materials. Especially for hair.
High frequency normals can also sometimes cause bright flashes of specular highlights.
Probably the best example of UE without TAA (by Epic) would be Robo Recall. It’s for UE4, all the features are still in UE5. Unfortunately I am not sure the content for it is accessible anymore, but there are live streams of how they built everything. Sadly I can’t think of anything more recent.
Just so you know, having no post processing volume does not mean you have no post processing. Just means that you’re using the defaults. It shouldn’t matter in this case, as I assume you’ve disabled Lumen/Megalights/Raytracing via project settings already so they don’t need to be set in the post process volume.
Yes, I am aware, I mean, I went through and disabled adaptive exposure, bloom, colour correction, etc.
I’ve been testing a range of content. That video was just a test on a more complex character and environment; it’s just a few “Paragon” assets from FAB.
The constant moving noise in shadows like static on a CRT TV … if you remember that :D, such as under the foliage and behind transparents, and the sparkles (bright points) you catch in what should be shadow in a few spots. That’s what I was getting at.
I am making a bit more progress with my latest settings,
The image here has much cleaner shadows, no blur even in a screengrab mid frame with her rather twitching animations … much cleaner. I am finding Virtual Shadow Maps add noise. This is mostly noticeable on soft shadows and with ambient occlusion so I still need to see what I can do there.
VSM relies on temporal accumulation for a form of raytracing (SMRT) in the penumbra if you have soft shadows enabled. Look at the VSM docs for more details, but this can be disabled for sharp, noise free shadows. However they will be so sharp that you will see visible stair-stepping.
Looks like you are also seeing dithering in the material. Paragon character materials were authored with TAA usage in mind. They generally don’t use real transparency, so the wings and hair of that character will be using dithering. Those materials would need to be adjusted.
