Hello everyone, I recently jumped ship from Maya and there are a few things I’m still trying to make sense of. So I’m trying to give my 64-bit style reflective cubemapped material a bit of transparency, but I’m having severe difficulties denoising it of “firefly” artifacting. Sorry in advance if anything about this question is stupid or out of turn on my part.
Welcome!
First thing first, what are you calling fireflies? Is it the noise in your screenshot here, or are there actual bright dots of light when you render in Cycles? Fireflies are usually defined as single very bright pixels sprinkled through an image.
Right now, your screenshot is in the material preview mode, which works using Eevee. If your complaint is that the material preview is noisy, you need to switch to Eevee to access its settings and increase the Eevee render samples. However, it might need lots of samples to fully resolve, as Eevee isn’t the best at semi-transparent alphas.
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Looking at this material, I immediately see 2 possible reasons why there could be actual fireflies in a Cycles render.
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You have a high transmission material. Cycles isn’t good at sampling light through refractive materials. If you have lots of light going through this material (example, it’s a glass window), it’s good to disable the shadow on the material. It can be done using the light path node to replace the shadow with a transparent material.
I see your alpha isn’t at 1. Were you trying to let more light through? I know some people recommend mixing transmission and alpha for this, but the shadow ray method works better, looks better and offers more control (you can change the transparent color to control the glass shadow). -
I see you have set the IOR level at 1 and the IOR at 2. This means that your material is exceptionally reflective and shiny. Depending on the lighting in your scene, this could cause reflections to throw bright spots around. Make sure you haven’t disabled “filter glossy” in the render settings. Also, make sure you have some indirect clamping (the default of 10 should limit fireflies, though it’s a bit severe and I can usually get away with much higher numbers).
Yes, I’m trying to get rid of the splotchy, noisy parts in the image at the top. Sorry that I used the wrong terminology, I’m going off what Google AI spat at me, which wasn’t all that helpful. Anyway, I’m trying to go for the kind of transparency depicted here, where you can somewhat see the object behind it. Once again, thank you in advance for bearing with a noob like me.
Well, your renderer is set to Cycles, so what you see in the material preview mode doesn’t matter for the final render. Try to switch to render preview, that will show you what will actually get rendered, with the actual renderer and lighting you have setup in your scene.
If you do intend to use Cycles, as is selected right now, I would also recommend switching the device to GPU if you even have a semi-decent one, that will help make the render fast enough so it’s actually useable. CPU rendering in Cycles would be very slow.
I also see in your screenshot that your direct light clamping is set to 1. I wouldn’t recommend clamping the direct light, it will just limit how bright your lights can be. It should be set to 0 (disabled). Indirect clamping is probably fine at 100.
What does the final render look like in Cycles? Does it render and denoise well?
I should also mention that the material preview mode you are using right now has a temporary preview background, so the actual render will look a lot more empty unless you add a background yourself.
OK, I understand now. For now, I think I’ve fixed it. Thank you!