At the moment, I’m rendering an image with Cycles. It’s nearly 2000 passes now and I’m pretty sure that the image hasn’t improved since around 500 or so, there’s still exactly the same amount of noise. I’m so sure of that, because I took a screenshot of the image editor after 1000 passes (around the time when I started to get confused) and after 1800 passes and they look absolutely the same. The comparison of the two screenshots even shows more of these nasty fireflies now. Here’s the screenshot after 1800 passes:
As far as I know, the image should constantly improve, but I doubt very much that this image will ever become noise-free or at least mostly so. Is this possible? The scene is not even very complicated, just a simple light behind a glass, that’s all:confused:
So my primary question is: Should I continue the rendering or isn’t it worth it?
Theoretical noise improvement in Monte-Carlo algorithm is proportional SQRT(N), where N= time or sample number. For example, in my experiments with outdoor volumetric scenes it stay very noisy after tenth of hours, 16000+ samples, and visually does not change. It is not bug, but feature of algorithm used by render. There are many ways to improve it, more perfect (quazi)random generators, stratification, importance sampling, all well known, but must be implemented or tweaked. With your scene, where main light source is close to surfaces some sort of bi-direction tracer (unimplemented) can help a lot. For now, try to avoid such scenes, light sources with glass close to it, or if it nesessary use top hardware/render farm, patience, and insane number of passes(samples).
For that scene, I recommend you use luxrender with SPPM.
The problem in your scene is that it is a corner case of the cycles basic algorithm. It will eventually become noise free, but it’ll take a whike.
You could use YafaRay 0.1.2 which implements SPPM rather well or LuxRender which I know implements SPPM but which I never tested.
Anyway, I’m doing research into open source renderers right now and I found that lux creates images which have less noise with the same amount of samples/pixel.
Hey guys, thx for your answers. I let the image render overnight now and nothing recognizable has changed, so that I decided to stop the rendering now at about 4000 passes. It’s a bit annoying, but I can live with it, I hope that Gimp will help me out a bit.
I’ve already had the idea to give it a try with LuxRender, which I used sometimes before Cycles was released and I never had such problems with it…maybe because the scenes were not as unfavourable as this one.
I’m 99.9% sure it won’t (may have the addon but can’t see the renderer). Why should it? Just go to the luxrender site and download it, not rocket science is it ?
As proposed I tried Luxrender and after a few hours it becomes quite clear that it was a good choice. The image is already quite noisefree. It’s certainly a good thing to have more than one renderer option
However, I think the interior material of the lamp as its roughness too high?