Pictures speak for themselves. First picture is perfect, but I need to turn the skylight up for the scene. When I turn the skylight intensity up, everything else in the ray trace reflections looks fine and accurate, but the Sky Atmosphere gets really bright. Like its Emissive turned up exponentially.
How can I fix this?
Wow, no response yet. I’ll attempt a suggestion.
A translucency setting in the water material’s general settings (when clicking in empty part of grid, or clicking main material node)…is not set correctly (either should be enabled / disabled, or a different value).
There’s also how reflections in translucency are affected by Intensity Scale / Intensity / applicable texture properties (viewed by opening a texture used in a sampler from the material editor).
This is not a translucent material.
In addition, I’m not seeing any material setting relating to “make Sky Atmosphere not get exponentially brighter in reflections when Skylight intensity is increased”
I haven’t seen that setting either. Is the material graph more simple or is it a complex one? Can you post a screenshot of it?
For the sake of simplicity, this issue can be reproduced with a Default Lit material with a constant Base Color of 1, a constant Metallic of 1, a constant Specular of 0, and a constant roughness of 0. Nothing else. As in, a material producing the basic level of raytrace reflectivity. Here:
It appears HDR/emissive colors get “overblown” when the color of the material is brighter, as you can see in the preview window. If I set it to a darker color like 0.1, it dims the raytrace reflection enough that emissive or HDR colors like the sky of the example forest scene in the preview window, or in my OP’s case the Sky Atmosphere, of course it also dims everything else so that’s not an answer. Here’s how that looks:
So, here’s the actual Sky Atmosphere color. Note, the clouds are unlit but their emissive level is between 0-1. This is important to note for the second screenshot showing the reflection:
It’s important to note because only the Sky Atmosphere is overblown in the reflection, when the Skylight is turned up to 8 intensity.
Turning the skylight intensity up doesn’t actually change the Sky Atmosphere’s visible brightness in the actual sky either. It’s somehow only causing it to look like overly bright HDR/emissive in raytrace reflections.
Again, for reference, here is the exact same reflective material but with the Skylight set to 1 intensity. It’s completely accurate, no problems whatsoever. Too bad I’d like to light my scene with a brighter skylight, huh?
It only affects reflection and not the actual sky because it is meant to. What would be the reason for increasing its intensity? If you are trying to light up corners try turn up GI to above 1 instead. If you are tring to increase the overall brightness try increasing overall light intensity or change up auto exposure instead. I’m not sure what your issue is but there is probably a solution that does not involve changing skylight intensity.
Yeah, that’s true; I wasn’t expecting the sky atmosphere to get brighter as the skylight is a separate actor, and we are correct, it doesn’t. So I’m surprised that it appears to get exponentially brighter in the reflection when I turn up the skylight. I figured the reflected world would know to exclude the skylight’s effect on the sky atmosphere just like the non-reflected world does. It just doesn’t seem…correct. Like, the reflection is fully accurate except for that.
Raytrace GI doesn’t actually seem to be affecting my scene all that much, if at all. Here’s my settings on the PP and the cvar r.RayTracing.GlobalIllumination 1:
cvar r.RayTracing.GlobalIllumination 0 (off)
It’s a very slight change toward the top end of the map, closer to the sky. None of the PP settings increase its effect. Perhaps I’m missing something? I’d like to try increasing the effect of raytrace GI.
Regular GI uses indirect lighting which is lightmass, right? My lights are dynamic/stationary so I understand that means I’m not using regular GI.
Anyway that slight change I’m getting isn’t worth the incredible drop in framerate that raytrace GI causes. If I could increase its effect perhaps I could try optimizing it.
If I can’t get the GI to help out then I guess I’ll need to litter my map with non-shadow casting fill lights and yeah, more actual lighting like the lamps?
OK this is helpful. Thank you. I was moreso concerned about what you addressed: this issue is happening and therefore is Skylight Intensity not meant to be turned up past 1?
So, with that being answered I have a few questions on my options like you suggested.
So, this is my scene with a Skylight intensity of 1.
I feel like, even though the Sun is at a low angle for sunset, the sky is still fairly bright. I think there should be more overall bounce/ambient lighting in the darker areas. Here’s how it looks with a Skylight intensity of 8:
I think the second pics look much better for the scene. So, if I am not supposed to turn up the Raytrace Skylight to achieve this, how should I go about achieving this with stationary/dynamic raytrace lighting in 4.25?
Here’s 2 other photos I couldn’t post in the same comment due to file size. First one is at intensity 1, second is a lighting I like more at intensity 8.
It’s not that you can’t turn it up to above 1, it’s just that it might not behave as you are expecting.
Think of the lamps you have in your map. How did you achieve that? I’d assume a mesh with emmisive material plus a point light at it’s location. So when you turn up the point light intensity, the environment lights up more, but the brightness of the lamp does not change. Skylight is similar to that. The skysphere and the skylight are seperate entities.
As for your issue, I can’t really provide a certain answer without having the project myself. My suggestion would be to try increasing global illumination in post-processing to above 1. It might have some other unexpected effects elsewhere so be careful with it. Alternatively just increase the brightness of the lamps in your scene and use them to illuminate.
OK, I’m getting good results with fill lights near the tops of the buildings and in the tight areas, and better performance with the skylight turned down lower and the samples per pixel at 1, since its intensity is less powerful too. I’ve turned GI off for now since I can’t seem to get it to actually do anything so I’ve saving performance there too.
I think this is the intended workflow still. Thanks for the help!
Sorry, for people coming to this thread for answers, I’ll quickly explain why this isn’t a good answer (as it’s submitted as an answer).
btw disclaimer, I’m coming from a UDK (UE3) background, and have been using UE4 since its initial release, thus having read most of the UDK and UE4 documentation many times over. So I didn’t re-research any of this specifically for this reply so I could be wrong here, but this is from my understanding.
1b) I’m not sure which DFAO settings you refer to in the PPV…there are DFAO settings on the Skylight, though, if that’s what you mean? But are you suggesting reducing DFAO from the skylight to brighten the level? I think that’s a backwards way of approaching lighting. In any case, DFAO settings on the skylight don’t actually change anything, I suppose due to the full Raytrace settings but I can’t be sure.
It’s been commented already that skylights should not go far past 1, and acknowledged by the OP that keeping it at 1 results in accurate reflections.
Yes, not plugging anything into a material’s specular results in a default value far above 0, possibly 1. As I demonstrated in my first reply to you, the material utilizes 0 as a specular, but this issue was reproducible with any level of specular.
Reflections/Reflection Environment document pages deal with raster reflections IIRC. Again, as I mentioned in my replies to you originally, OP is dealing with Ray Trace Reflections, which are supposed to be mostly automatic. Using the material I set up, that SHOULD get you a clean reflections, and it does, except for when you’re using a Sky Atmosphere and a Skylight above 1 intensity; at that point, there’s discrepancy in the reflected emissive strength as per all my other comments.
…TBC:
Let me know if I missed something.
One point to set here is strength of reflections takes into account the specular. If there’s no value / parameter plugged into the specular pin, then there’s a default for it, and I think I remember reading it’s 1. However, this might only be in certain types of materials. This is difficult information to be aware of while building a scene, so I suggest researching that a bit. Probably by reading the Reflections doc pages, including the Reflection Environment.
Another point is about indirect lighting. When lights are stationary / static, indirect lighting is baked, or created by Lightmass. Movable lights comprise a combination of methods / techniques, one of which is the Volumetric Lightmap, though that can be excluded I think in certain cases. When I look at the screenshots of darker areas between buildings, I see a lack of detail and not much indirect lighting. Distance Field Ambient Occlusion settings in the PPV are capable of brightening and darkening those areas. Look up the page on it to see what the different settings do. In terms of the reflections, skylight intensity shouldn’t be far past 1, yet a directional light modification could be a part of the solution. The base color property of a material, and the specular, are figured into the calculation for reflections. So, it’s pertinent to research a bit more on those aspects of reflections and how it connects with the skylight / skysphere.
Not exclusively talking about reflections, the sunset sky can be modified by changing the skysphere atmospheric fog properties (Rayleigh, Mie scattering, directional scattering, and basic settings at the top too). I can’t say which settings precisely need changing to exactly what values because it definitely relies on other factors in the scene that I don’t know about for yours. But, a few that are probably essential to it are density, scattering coefficients, and color.
I didn’t submit it as an answer intentionally. There’s something wrong with posting in the forum for me. When I initially post, it doesn’t work clicking on “Post Your Answer”…so I need to reload the page and then it has logged me out, so I need to click the big blue button again to submit the response. In effect, it posts what I wrote as an answer by default, rather than a comment. I could re-login, and it would then have the usual options of Answer or Comment, but I didn’t that time…I forget or don’t go through with it sometimes. So that’s why it’s submitted as answer. It’s obviously not a solution for your problem definitively. I was trying to get at the underlying potential cause.
To respond to the points you made:
I converted my previous attempt at helping to a comment. Please try to go a bit easier on me as I’m newer to Unreal than you.
HELP for ‘r.RayTracing.Reflections.RayTraceSkyLightContribution’:
Requests ray tracing reflections to use ray traced visibility rays for sky light contribution similar to sky light ray traced shadows. A Sky Light with ray traced shadows enabled must be present for this flag to take effect. (default = 0)
r.RayTracing.Reflections.RayTraceSkyLightContribution = “0”
