Why, so many fireflies?

8 out of 10 times I don’t have any problem with rendering and “Fireflies/Noise” but this time there is plenty of them.

I have try samples 500 and 1000 but still have noise.
Can you take a look at my blend file and se whats the problem is.
Thanks in advance.


Ok, I’ve had a look at your .blend, and there seem to be 2 issues:

  • Change your HDRi Image, some of them have small brighter bits, and these act like small area lights, which are harder to solve than larger, more even lighting. I noticed this because I had to select a HDRi as one wasn’t included, and depending on the type I selected, some produced the noise shown in your image, and some didn’t.
    If you really don’t want to change the HDRi Image, then make sure you turn on Multiple Importance Sample in the World panel, its under settings at the bottom, that will help clear the noise up a lot faster.

  • Whats with the weird Wooden floor material? Unless there’s some super special effect you want, a simple mix of a Textured diffuse material with a glossy mat (no texture) should do fine. Shouldn’t be affecting the mix by a glass shader anyhow.

Thank you zeealpal for helping.

I would also set teh roughness manually.
In the world settings, select multiple importance sample and set the map resolution to at least 1024.

If you’re using cycles, you should adjust the clamp value. That’ll keep the number of fireflies down, although it will bring down the overall brightness of your scene. Also, you could run it through the despeckle filter in the blender compositor to bring down the overall amount of noise.

Fireflies are overbright pixels. What you have in the image is just noise.

I ran through your file, and since I didn’t have the image textures, I switched the hdr image to a sky texture, and the wood floor texture to a white RGB. I also changed the feature set to “supported.” It looked fine at 500 samples. Also, did you render the image in GPU?

If i may, what is the idea to drive Layer Weight blend input by Glass BSDF output?
Object’s Reflection coordinate values can be used to adjust Roughness of the Diffuse and Glossy nodes in theory but i doubt if that would make any art related effect on image.

Use of HDRI almost always makes image grainy - it takes a lot of samples from such image to light the scene. MIS is supposed to take certain care of that. Try to imitate Environment lights using Emission planes and Sun at first and see if this gives better results. You could use image mapped on Cylinder or planes (visibility for camera off) to imitate reflections on the car or make special texture and map that on car using Texture Coordinate Reflection output.

Remove Doubles on grill object did remove 72k of vertices and shape is still there.

Thank you all for helping. Sorry I don’t have any GPU. I run on a iMac 10.9.2 mid 2011 and have only CPU.