4.24: Sun & Sky Ray Tracing GI

Development Rendering
1

When I turn on Ray Tracing the GI when using Sun & Sky System, I can’t see any difference.
I increase the bounces - no GI to see.
I switch between Brute Force and Final Gather.

GI does not kick in when using Ray Tracing.
Is it a bug or am I just missing something here?

Thanks a lot

2

Ue4_Cam02.jpg
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Working for me. This is being light with the hdr backdrop setup and screen space gi. It’s working with sun/sky and brute Force/final gather go as well. More info about your scene is gonna be needed.
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3

That’s strange. I wonder how you can get your GI so clean.

watch this:

Download the Project File here:

it’s a super simple test and you can clearly see the splotchy problem.
What the heck am I missing here? :rolleyes:

4

GI.jpg
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Your sample scene is really small and the only light coming through is a small window. This is going make GI struggle to light up the room.

That said, your GI is working you just need to increase the Skylight Samples and the Raytracing GI Samples. Set both to 16 and the big splotches will go away, it will still be noisy simple because the scene has very little light passing into the room.

Also even with a 2080ti Raytracing GI tanks my fps so be aware of that.

I posted a couple videos over on youtube if you want to see how the performance and quality has been.

5

oh man, thank you so much. You are awesome.
Soo… when you say, set the Skylight Samples and the Raytracing GI Samples both to 16.

Do you mean, the samples inside the PostProcessVolume?
Or somewhere else?

Also… if the GI calculation takes such a crazy time for real time ray tracing.
Could we mix it?

  • I mean… what if I just bake the GI?
  • Can I do that?
  • And if so, how can I mix the baked GI with the Ray Traced Reflections, AO, and Translucency?

Any thoughts on this?

6

an one more thing… the Ambient Occlusion seems to be as funky as the GI.

Video:

I think baking the GI and the AO would be a good option.
But for some reason, I can’t figure out how to do that properly.

I just don’t know what the heck I am missing here!

  • I just add sun and sky (also change the Samples per Pixel to 16)
  • I assigned one material, just a grey clay material with zero reflections
  • All objects are set to static and do have non overlapping uvws
  • I add the PostProcess Volume and activated DX12 Rayt Tracing for GI + AO
  • I make proper adjustments to the settings
  • I hit Build Lighting only (Production Mode = I am assuming is better than High Quality_=?)

The Baking Process for this test scene file takes 30 seconds.

Now what?
If I am going to assign materials with different texture maps, etc.
How can I mix it with the Baked GI and Baked AO?

And… is the baked AO saved with the Lightmap of the GI?
Or is the AO separate element?

ufff… kinda confusing. but would love to figure out how that stuff works if we are going to combine GI+AO baked plus Real Time Ray Tracing for Relfections + Translucency.
Or is this just not possible to do? :rolleyes: