Does anybody know how to make the indirect shadows render ok with the DDGI volume from Nvidia RTXGI plugin?
No matter what probe density setting I am using, indirect shadows refuse to render with an acceptable quality.
Also, the probes disappear completely and DDGI turns black when I choose some configurations for density. For example it can work with 64x64x50 but go black with 64x64x64. They can work with 24x24x24 but go black with 24x24x32. I can’t seem to find a pattern when they turn off.
I’ve also attached a path tracer ss for reference. The scene is lit with a rect light bounced off a wall.
I never bothered to try the RTXGI because it was my understanding that this was just how the effect worked; It raytraces a sparse grid and so the lighting detail is inherently sparse. This is what allows it to be temporally stable and still run at high framerates. The demo that they ran during Epic’s livestream really highlighted this issue: The indirect lighting is extremely flat.
With volumetric lightmaps you can mitigate this with distance field indirect shadows, but I don’t know if that is supported by RTXGI. You might be able to enable SSGI as that has its own indirect shadow effect, but again I don’t know if that will have much impact as supposedly it was enabled in the Epic livestream and it comes with all the problems every other screenspace effect have.
I’ve already tried the combination with SSGI and that causes a ton of other issues for this test scene. It’s usable in bigger environments, but in this or other small rooms it’s not quite ok because you’ll loose walls out of frame, that bounce a lot of light on the scene, very easily and that is a very big lighting change. In the livestream SSGI was used only to fill certain occluded areas more.
I partially agree with what you said. I believe that if it has GI in the name, than it should do what it says on the tin “Global Illumination” that includes indirect shadows. I can accept those to be of a somehow lower quality for speed, but what you can see in my example is really really bad. I am still hoping I am doing something wrong or the system doesn’t work for me as it should.
“Global Illumination” that includes indirect shadows. I can accept those to be of a somehow lower quality for speed, but what you can see in my example is really really bad. I am still hoping I am doing something wrong or the system doesn’t work for me as it should.