I don’t know if it’s a bug or we have to wait some optimization.
But, this scene, believe me, it’s very complex. Many spot lights (Meshlights, cause real Corona lights create a more noise) and strong indirect illumination from the skylight make me crazy.
By the way, I don’t know why, there are a lot of noise, after 3 hours, only in DOF and chrome object. Like when I use sub-pixel mapping on in VRay…
I tried different setting (PTS = 4) but it doen’t help me.
And, if I use LSM= 1 ( Light Samples multiplier) I have a loooot of noise near the walls, where the lights emit “light”
Out-of-focus higlights are very hard to render with the current version. You have to fake it (remove the higlights), and wait for adaptivity, which may hopefully help
I’ve found that bucket rendering is actually a lot more efficient for dealing with this type of noise. The bucket rendering in Corona does some adaptive sampling. It’s not great, but it can help. The key thing to remember is that after a certain amount of time rendering, the total error (noise) in your image will be exactly the same regardless of whether you use adaptive sampling or not. The key thing about adaptive sampling is that you can focus the sampling on the noise that’s more easily noticed. If an image is so clean that you can’t spot any noise in it at all, except for one region of out-of-focus reflections, then Corona’s progressive mode isn’t going to do you any favours. While it is still technically reducing the error even in the “clean” pixels, you’re not going to notice the difference. By using bucket mode, you can increase the noise in the less noisy region to instead reduce noise in the noisy regions. Basically evening out the noise profile.
Look at the two attached images. One is rendered in bucket mode, the other in progressive mode. Both images refined for five minutes. The bucket render has significantly less noise in the out of focus highlights, but is somewhat noisier in the flat regions of the image. Overall, I would say it’s the more pleasing of the two. Look at them up close and decide for yourself.
The bucket render was done with 1:5 bucket steps, with a threshold of 0.05. Lowering the threshold will reduce noise in the less noisy regions, but increase noise in the noisier regions, because a lower threshold would catch more pixels for refinement, which means it will complete fewer passes.
Nice1 I have to try!
Ondra what do you think? =)
Captain Obvious, can you share your sipple scene. I prefer “to test” the same scene.
Did you try with very low PTS in progressive? Like 1 or 2?
I think Captain Obvious obviously knows his shit, he is correct ;). There is some (very basic) adaptivity implemented for bucket rendering due to historical reasons (I had to do adaptivity to get some extra points for some school project ;)).
Mmm… I try in a simple scene. If I use Bucket mode (PT+HD) , with the last build, I see a green dots in the final render. If I use PT+PT everything is ok.
Yeah, it’s not the best adaptive sampling I’ve seen.
I’m not entirely sure what the “adaptive steps” does, but it seems that the total number of samples is base^2 * steps^2, so if you set the base to 1 and the steps to 5, you can get 25 primary samples per pixel, if they’re noisy enough. It seems that Corona compares the pixels against the fully rendered image rather than just the pixels produced in the current pass, so when you use bucket rendering with adaptive sampling, each pass will take a little bit less time than the one before (because there are fewer noisy pixels).
Also, I had some problems with PT+HD, where you could see differences between the buckets. Not sure what was causing that. It was fine with PT+PT. I haven’t tried the latest build though.
Edit: attached the scene.
Edit again: Sorry, I just realized I’d actually changed the bucket settings… The scene attached uses 1:3 with a threshold of 0.15. Those aren’t good settings. teapotDof.max (204 KB)
