Hello, when rendering with EEVEE, for some reason, the material is flickering with White Spots like this. When the camera stops moving, the light spots are still there but they are not moving. Do you know how to fix it ?
Welcome!
Are you doing the fog using a volumetric material? That might be the cause. Eevee’s volumetrics look nice, but there is a bit of settings adjustment needed.
Here are the settings I’m talking about, at their defaults.
You may need to adjust:
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The volume start and end values. Eevee’s volumes work by placing slices of volume (called samples) at various distances in front of the camera. The start value shouldn’t be smaller than it needs (it would waste samples in the millimeters in front of the camera) and the end value shouldn’t be farther than you can see the volume. You want to concentrate the samples in the range where they matter.
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The tile size. A smaller number means higher quality, but slower render.
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The samples. It controls the number of volume slices.
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The distribution setting makes the slices more clustered closer or farther from the camera. The default value is usually fine if you adjust the rest.
I test it, not really working. When I turn off the Specular in Sun Light, it helps. But some are still here.
I think it somehow related with Roughness, but I am not sure
Do you have a sun shining through a water surface? Then, could it be a low quality shadow of the water surface being cast on the ground? If you go in the shadow settings and increase the resolution of the “cascade size” (sunlight shadow quality), does it change the look of the glitch?
yes, I use Sun Light without shadow to add some light to the scene. Turning off the Specular helps a lot.
I found the problem somehow related to Roughness of the Material. I used Color Ramp to control the roughness, and somehow it’s made these bright spots. Disconnecting the Roughness removes the problem. I just don’t understand what is happeiing here.
Would you be willing to upload the scene so I could take a look? Maybe I could figure out what the actual problem is.
If you don’t want the project to spread on the Internet, you could delete all objects except the water, light and ground.
This is the blender file.
Ah, I see the problem now, I was thinking the main problem was the big flickering in brightness, I didn’t realize those were caustics. The white dots on the rocks are so small I missed them at first.
Well, the problem here is that you are reusing the rock’s very dark color texture as roughness. This makes the rocks very shiny, and the way you setup your color ramp makes them even more shiny (the rocks basically have a roughness of 0 over their whole surface and their speculars are very sharp and small).
This texture is not suitable to serve as roughness, because it has very little brightness variation. I would just disconnect it and set the rock’s roughness to a high value like you did. Rocks underwater usually don’t look shiny anyway, unless they are made of crystal.
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Thanks for your explanation. It should be the reason. I learn the way to make a simple PBR with just 1 image only. Turn out there is a problem with this cheat.
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If you manage to do it with one image, that can be a good thing and save on memory, but not every material is going to be possible. Sometimes, you are going to need a roughness or bump texture that doesn’t match the features of the color, then a full series of specialized images will give the best result.