Cycles - Night Scene Noise

I’m trying to setup a nighttime scene, and in the circled areas, I’ve not been able to clear up the noise much. I’m not sure if it’s a cycles limitation at this time, or if I need to provide a better material or lighting setup.

This was modeled in Blender 2.61, and I ran Cycles for 8000 iterations. It doesn’t look any different from the 4000 iteration version IMHO. I’ve tried Glossy and Diffuse Shaders with lowered bmp to reduce shinyness.

Any thoughts, ideas?


Are those mesh lights in the lanterns? If so, they’re probably the reason. Turn them off (to keep them bright, but prevent them from casting any light put on them an emission/black diffuse mix shader with Is Camera Ray as factor input) and in their place put Lamp object with an appropriate size set. Lamps clear up much faster.

The problem surface have too small angle to main light sources, and because of Importance sampling lights have too small probability to reach surface from eye>light direction, but when ray hit it will be too bright compared other near pixels, so noise appear. Try to place another light source close to normal direction to that surface, maybe point light, it clear noise very fast in close range with small number of bounces, because of Direct light feature. Or hide that surface using some obstacles from lights that placed too far from surface normal direction.

BTW, maybe we need option to turn off Importance sampling of cosine weighted half sphere, it can help in such cases (light rays spread more even, but other parts of image will sampled less as well).

@MadMinstrel, thanks I tried replacing the mesh lights with area lights and that took care of my lighting and noise problems. I’ve got alot of fireflies now in similar places, so I’m going to do some more study, and see if Storm’s suggestions can help me work out the fireflies.

I was having the same problem and this helped me out…Thanks…I am doing a city scene and have replaced emit lights with dot lights but would like to know how to set it up so the lights are still reflected off the walls of the buildings…The camera ray node means it doesnt give relection …any help would be great.