Y’all at least can see something, meanwhile I can’t see anything when turning raytracing on. I am using 2070 Super, and haven’t been able to play a single game with DX12 normally, either crashes or some other bs, as well as raytracing simply doesn’t work in UE4, not that it glitches out or bug out like the rest of examples here, meanwhile I am having different problem that when I move my mouse cursor over to any side panel that is outside of work/scene area, it just goes black with glitched information text of where ever I am hovering my cursor. I already reported it back in previous update, but literally the same exact thing is happening on 4.25.
It basically turns into black screen, and whenever I click in the middle where the scene area is supposed to be, I can see again, but that’s about it, the moment I hover outside of it, it turns black with glitching text around…
I seem to be having the same problem with HDRI skylight ray traced shadows looking subsampled as well, and I’m using a RTX 2060 Super… Has there been any solution to this problem?
I have noticed that the sky shadows accuracy problems comes from the sky light denoiser. If you disable it, it will work fine, but you will need lot of more samples per pixels to compensate the disabled denoiser. Maybe Epic will read this and they could add a system to control, at least, the denoiser agresivity, to make it less noticeable.
If we report here some problems with screenshoots and proofs, maybe we could finish making a new thread on the suggestions section of the forums, or report some bugs.
I tried the global settings tweaker from Market place, that seem to do the trick for skylight shadows!
My other issue is the indirect lighting, compared to the path tracing snapshot seems to be extremely imprecise, is there some settings I can tweak to get closer to the path tracing version?
That’s my tool! Even if you were able to make the changes to the skylight without using it too, but how did you solve it, disabling the Sky denoiser too, right?. (I would want to use this encounter to ask you if you could rate it into the marketplace, please, if you like it, as it’s always useful for developers. Thanks!)
Mmm not sure about the difference in your images, but it’s true that path tracing works slightly different than raytracing. Maybe you need to set high numbers of samples and bounces, and global illumination.
You can also share a very basic project with the forum (like that room with your settings), so anyone here can read, try it, and maybe be able to give you the solution, if any of us find it.
I kept reporting this issue but they kept rejecting it
Basically when using Final Gather mode, the indirect bounces setting is unfrozen but the indirect bounces value has no effect. It has only effect on Brute Force GI mode, which is much slower but allows you to use multiple indirect bounces to get closer to path traced result.
I tried to explain it to the Bug Report submission staff twice but they never understood it. Unfortunately, sometimes when you report UE4 bug, your bug may be triaged by someone who has little to no understanding about the area of the engine the bug occurs in, and will just haphazardly reject it
Essentially I want to achieve an archviz exterior/ interior hybrid, without relying on rectangular lights at window openings to help with interior indirect lighting. And just using either an HDRI skylight based lighting or directional light + skylight to light up the scene. But the issues with raytraced indirect lighting looking subpar (compared to baking with Luoshuangs GPU lightmass) are whats keeping me from using GPU Raytracing as a more time efficient lighting solution.
Not sure how to attach a project file onto here so members on this forum can take a look, its about 100mb big.
Oh, it’s a pitty. But you tried to explain it with images, videos and even sharing projects where you have prepared comparison/proof scenarios? For this kind of things, we must put the things as easy as we can. For example, with your only writen previous writes, I didn’t understand a lot… also, of course due to English is not my native language. But graphic information is the most valuable one!
Thank you!! I have sen it. This helps a lot to continue motivated and improved, more than any money
I see… I haven’t still tried, but I wil do with your scene; I’m curious, but prbably we will always need square lights on windows, as maybe Global Illumination is too expensive and/or imprecise to bounce enough to illuminate an entire room indirectly.
You can share a project (to evidence one thing, as commented above) through Dropbox, Drive, or Mega, for example, sharing the generated link for an uploaded file (a compressed ZIP is the standard).
The problem with UE4 currently is that it’s quite cryptic to determine if the outside environment is sampled using importance sampling or not. If you have SkyLight present, but ray traced shadows on it disabled, but GI enabled, I am not sure if GI uses importance sampling when sampling environment or not. Anyway, to be on the safe side, you should generally first use ray traced skylight to make sure you direct lighting from your environment is right, and once that is verified, add GI for secondary bounces.
HOWEVER:
It is true that currently, ray tracing performance is still not good enough on current gen hardware to get accurate enough skylight direct illumination with reasonable performance for interior spaces. Sampling exterior environment from inside of a room with relatively small windows is still very expensive. That’s why we still have to fake it by placing invisible area lights into window opening. It’s a direct throwback to ancient late 2000’s / early 2010’s workflows. Ugly workflows where you have to manually eyeball color and intensity of your area lights to at least roughly resemble exterior illumination, otherwise you may get a brutal mismatch between interior and exterior exposure, resulting in often very unrealistic results of exterior environment being drastically underexposed compared to interior illumination.
In offline rendering, during the times when environment light sampling optimizations weren’t as advanced but requirements for realism and accuracy were already pretty high, this issue was solved by “portal lights”, which were usually a mode of area lights, which used direct area light sampling to project environment illumination from the outside. This still required you to manually place some sort of helpers or geometry inside the window openings, but it did not require the annoying step of trying to manually match the exterior illumination color and intensity on your invisible area lights.
I have made some research and, for an interior, (but would be important to check the same settings for an exterior, to confirm wich one “matches” for both scenarios at the same time), the best thing is to set Sky Light as Satationary and not as Movable.
Gathered GI seems to not work properly, or to not bounce more than once, even if you increase the number.
And to light the interior by the exterior lighting you can: increase Sky Light intensity, decrese Sky light distance thresold, an/or use Brute Force GI with more than 1 bounces (the higher it is, the better).
@Rawalanche , is a good idea! Unfortunately almost all of my suggestions was unseen too
The brute force GI method coupled with the skylight denoiser seems to do the trick! And it’s just with HDRI skylighting, Later, I’ll post some snapshots of another scene that I made that illustrates this. Brute force is very costly with the increased samples. I only have a RTX 2060 super atm… I should upgrade to a 2080 instead XD
You guys are having an interesting discussion. It’s readable in the doc page on RTGI that Final Gather is limited to 1 bounce and should be set at a minimum of 16 samples. I’m not trying to upend these experiments or research. It’s simply interesting that a long discussion is confirming some points that are in the doc pages. I’m considering getting a computer with a 2060, so perhaps I need to go for a Radeon RX 5700 / 5700 XT instead, as it’s 8 GB and I never read of issues with it, and it’s at a lower price point. What I think is still a major issue is AA at lower level quality settings, or mid-range settings. I see videos and screenshots of projects which were created using production level and high material settings, etc., that contain easily observable stepping and other AA artifacts. My opinion is it’s associated with something similar to the noise from lighting, and possibly also UV mapping standards, but I’m a beginner still…so my opinion is too far-off to imply having value.
I want the screenshots! (Are you disabling Sky denoiser, or enabling it? but it cames enabled by default).
PS: even with a 2080 ti the thing would be slow… for realistc results, it’s much better and cheaper the trick of rect lights.
Haha, I think we didn’t see that! They have been updating that page. Anyway is interesting too the imprecise Sky light shadows when denoiser is enabled, and the differences between a RT Sky being Static, Ctationary or Movable.
PS: if you wan’t to ray trace, you will need to buy a Nvidia GPU.
Here are some snapshots, w/ skylight denoiser disabled, scene is rendered only using an HDRI skylight, with Brute force RTGI selected.
Does anyone know how to reliably render a movie sequence from sequencer using Brute force GI? I’m getting distorted lighting results when I render out an avi file.
The first image looks excellent without the skylight denoiser. Is there a skylight in the scene that’s separate from the HDRI backdrop actor (meaning it’s not inherited in the HDRI)? If so, may need to delete the separate one and modify the HDRI one to correct for the change from deleting the separate skylight.
The backdrop has a skylight that is inherited with it on placing it in the scene. The settings for it, and the actual backdrop’s image, also influence how it lights the scene too. In the page for it, the suggestion is to delete any skylight(s) in the scene prior to placing the backdrop so there’s not two skylights with different settings resulting in unintended lighting that’d be difficult to tweak to intended results. There’s a few other suggestions / caveats in the page for HDRI backdrop too.
It’s quite different from a cubemap since it requires a ground plane that is set correctly, and relies on dynamic skylight and dynamic reflections as components of the backdrop actor.
Even if you were able to make the changes to the skylight without using it too, but how did you solve it, disabling the Sky denoiser too, right?. (I would want to use this encounter to ask you if you could rate it into the marketplace, please, if you like it, as it’s always useful for developers. Thanks!)
