The question that came up always is that how do you get rid of fireflies in Redshift? shaders. About fireflies, I’m talking about these little bright pixels we get on the object, looks a little bit like noise but essentially it’s just very sparse bright pixels.
Fireflies are notoriously bad in subsurface scattering materials generally. They are usually caused by the fact that when we press render we firing lots of rays to sample our scene or sample our Shader
Some of these rays are hitting like bright light sources and some of the rays coming back in just overloading our shaders so we are getting very bright spots. Sometimes is the case that maybe the lights in your scene are too bright, with subsurface scattering as well sometimes is the case that may be the color of your subsurface is just a bit too saturated.
Redshift Material settings
We select the redshift materials and open the materials parameters and comes all the way down to the subsurface parameter
It is the single bounce subsurface you will get on the object. This isn’t too bad you can see if I actually bring the saturation value up here to 100 Percent. It’s actually getting much much worse as you can see in the above image.
So one thing of course is just to watch levels of colors and lights in your scene if you’re using very strong lights or very strong colors. Rightshift is a physical renderer so this kind of unnatural value will give you a lot of noise and unnatural fireflies in your result.
But of course, sometimes this is what the client wants and you have to abide by that so how can we deal with this and adjust these values to make them less saturated or darker.
How can redshift reduce noise?
The first thing we could do is up the samples. So let’s just go here to check all unified samples. So I’m using here Sample min of 8 and sample Max is 256. Adaptive error threshold 0.01. This is a fairly standard default setting but we actually going to increase all samples here on the sub-surface.
So we increase the subsurface like 16*2 ie 32, then again 32*2 ie 64 like *2 every time we increase until we get the clear result. So here we will go up to 512 then we approach another method.
As you can see after increasing the subsurface samples to 512 things have not changed too much.
If we come up with our render settings under the basic tab we have the sample filtering tab.
So essentially we can clamp the secondary rays, I’m talking about reflection rays and refraction rays, sub-surface rays with this Max Secondary intensity here. At the moment is set to 4 so it’s meaning that our maximum level for any ray that passes through the shader it’s going to be 4.
So you actually reduce this and clamp this further, its gonna help out to reduce these bright spots here. So we half the Mac secondary ray intensity 2. so you can see straight away this is looking better. Let’s get a little bit lower is well maybe 1.2. We actually pretty much got rid of the noise now.
You can perhaps increase your subsurface shading samples a little bit just to clean up the overall noise but certainly, now the fireflies that we had before are pretty much gone now.
So this is an idea because we have in fact reduced the scene lighting a little bit by bringing this down but it does definitely help when you’re dealing with these very strong values. So the default value of 4 is normally found for most scenes.
If you are dealing with very strong values it is worth maybe having a look at this and using this to calm your secondary rays. This is also very similar to what you have in Octane called the GI clamp.
I hope this article is helpful a lot and now you understand how do you get rid of fireflies in Redshift? and achieve the result more quickly and get amazing results!