honestly this was going to be sent to the finished work page but i still think it needed more. i would like to know how do i get rid of those fireflies and any other feed-back on this render would be appreciated, also a big thanks to andrew price for the tutorial he put out.
You obviously have done some post work on this, correct? Because the “fireflies” appear to be blurred, and fireflies are artifacts of the render and occur at a pixel by pixel case. So if you used depth of field for focus, they should be confined to a single pixel of space and not blurred. I always prefer to use actual camera focus rather than a trick in post, but if that’s what you prefer, that’s cool.
My understanding is that fireflies are a product of the path values as cycles refines the render. So when a pixel has a high value (over 1) it appears to be white and substantially brighter than the pixels around it because it hasn’t had time to be refined. That’s why overly complex scenes are prone to more fireflies than a simple cube scene. However, I am not a technical pro when it comes to rendering, so someone might correct me.
With all of that said, I the best way to remove noise is dependant on the scene itself, on a case by case situation. Depending on what is in it, some methods of noise reduction takes away from the scene. Any of the following would probably help though:
Turn off caustics. Caustics are only important when dealing with refractive materials that project and bend light - like a vase with water in it. If you have something like that in the scene, it will probably look less realistic without caustics and might not be what you want. In your case, I think you would be fine without caustics.
Turning up the clamp value. The clamp setting lets you clamp a pixel value at whatever integer you set it at. Each pixel can have a value higher than one while cycles is calculating, but your screen can only display up to a value of one. So as cycles is calculating the pixel and evaluating what it should be, the pixel could have a value way above 1, which can cause fireflies because those paths take longer to calculate. So you can tell cycles to clamp pixel/path values at 1, so that it can stop it at that value and resolve it from there, so you get a faster render time and fewer fireflies at low sample renders. Once again, you lose some accuracy and I find scenes appear darker and less accurate, especially with glossy materials.
You can also simply use more samples. Cycles will be able to use more samples, and thus give you a more accurate result and resolve fireflies. But obviously this means you will have to wait longer.
Those are basically all I have for getting rid of them in the raw render, but there are also some compositor tricks.
If you render the image at a higher resolution (a scale of 150%+), drop the result in the compositor (or another raster image editor), and then scale it back down to the original size, fireflies are now antialiased and spread across subpixels, so they are less noticeable and in some cases seem to vanish. The larger you render it, and larger you reduce it back down again, the better the results. This also helps with antialiasing sharp/harshly contrasted edges in renders for the same reasons as above.
Lastly, you can render out different passes for different materials and calculations, and then you can single them out in the compositor. So if you find that it is only glossy materials that seem to be getting fireflies in the scene, you can isolate those pixels alone and then blur or work on them in some other way.
That is all I know about, there might be some more techniques, but like I said above, I am not a pro with all of the technical rendering details. I hope this essay helps… sorry for the length.
I can’t give any advice on the fireflies that hasn’t already been said, but i can say this; The helmet needs actual modeled detail. I can see that the texture is giving most of the detail here. Also, what was a spartan doing in a tunnel like that? and why is his light still on?
But aside from that, very nice.
i really am grateful for your reply’s and everything you said was really helpful. i did not know how these fireflies happened or where they came from so again that was really good to know all this information. and did everything you told me and i made a few changes to the material.
As far as I know it helps if you turn on multiple importance sampling for all “big” lights. Like HDR-maps, sun and big area lights.