I recently moved a 4.26 project to 5.0, and enabled Lumen.
The project features a low-poly style, which means the issue I’ve encountered becomes very noticeable.
My metallic material (simply a lit material with a palette texture for base color, 1/1 Metal, 0.3/1 Rough, and 0/1 Specularity) has become rather grainy post-Lumen. My other material instances which aren’t designed to look metallic look just as intended.
I thought maybe it had something to do with reflections or something, but trial and error in that department has gotten me nowhere. My remaining guess is that this issue is actually present on the other materials as well, and is somehow just accentuated on the metallic instance?
Whatever the case, I hoped someone might know something about Lumen, or lighting & rendering in general, that I’m missing. I’ve attached an image that demonstrates the issue; let me know if there’s any other information, context, or screenshots I could provide that can be helpful to solving the issue. I’m almost certain there’s just something very obvious here I’m overlooking.
Are you using a parameter or a constant/texture sample into the metalness and/or roughness? I remember reading once that a user noticed visually worse quality in an unbuilt project for metals using parameters. If memory serves, the visual quality was fine in a built project.
Also keep in mind that semi-rough reflective surfaces are hard to raytrace without noise even in the best cases. You might consider using screen space /cubemap reflections on these surfaces, as an accurate reflection is less needed on a surface that lacks sharp reflections.
Hello I don’t know if others run into this problem and stumble in here to find a solution, but here’s what I did to fix this when I ran into this problem:
On your light sources make sure that the Source Radius is half of the Attenuation Radius.
Example: My source radius was 1000 with a attenuation radius of 1000, but when I halved my source radius to 500 it immediately fixed the issue when hitting play.
I can’t figure out why this fixed it though ^^