Hi guys,
Again I am having these problems. I just can’t figure them out. I always use the same settings on my scenes, and every time I have one with reflective materials and dark grey colours I get so much noise on them. I tried using a high preset for irradiance but that gave even more noise, I guess due to higher max rate. Usually I just use medium setting. I also tried reducing adaptive amount from 0.85 to 0.7 but still not good enough. Since I use LWF, with gamma 2.2, shouldn’t that take care of noise in dark areas? With the same setting as for the light scenes. Though even the lighter object, the one with BB1 has way to much noise for settings this high. Please help.
your render setting images is so small that I can’t see your settings
Not sure what resized them, maybe because they were gif. Sorry, I reloaded them.
yes, looking at it now
It doesn’t seem noise, to me they seems gi splotches.
Do you inspect render elements to find where these splotches are coming from?
Is it IBL?
As first attempt I’ll stay with medium gi settings evntually raising HSph. subds
Thanks guys…
zeronove, how do I inspect render element? I can add it to render, but what will I see on it that would tell what is causing the splotches? Yes, I too think these are due to GI. Is there a way to distinguish if they are caused by primary IM, or secondary LC?
You would leave -1, -3 and play with HSph. subdivs?
well, if you add a GI element and it shows the splotches, then you know for sure they are GI spotches 
…so you can exclude reflection and glossiness issues and start tweaking only with parameters that are GI related.
as first attempt, yes
what about lighting? IBL, VRay sun, direct or whatever?
Just vray sun…oh and small vray light spheres in the ceiling, and indirect green light.
I’ll check GI now.
Not sure why I always ignore HSph. subdivs and only play with min/max…anyway, that cleared it up pretty well. I put it to 80 from 50.
I will now try to increase LC to 2000 from 1000 to see if that will clear the rest (the doors are still a bit splotchy and some other surfaces). If not, than I’ll try HSph. 100.
Thanks!
Hi,
if you add a GI element and it shows the splotches, then you know for sure they are GI spotches
Will be helpful if you post the render elements: V-Ray GlobalIllumination, Lighting, Shadows, SampleRate
Also the settings for the Sun and the other Lights you are using.
Very important, check your samples. Render with show samples on.
High settings (min/maxrate, thresholds) sometimes creates way to much samples
wich results in a higher rendertime and a blotchy image.
Bad
http://sorceress.netfrag.org/optix/bugs/s\_irmap\_problem\_01.jpg
Good
http://sorceress.netfrag.org/optix/bugs/s\_irmap\_problem\_02.jpg
Adjust sample distribution with thresholds and min/max rate so that you have
many sample in areas like corners and as less sample as possible in large even areas.
good tip, I always forget about this option, …better if it would be available as an element
Don’t stop on this quite yet. Your GI is still really splotchy and not good (though it’s better). Turn on Samples for IMAP and compare it with what Samuel posted. Read the help and figure it out better.
Sample rate isn’t being very adaptive at all. Spread out your values more (you’re using 4,8 ) try 2-10. You’ll probably see render time go down as well.
For your imap, your samples aren’t horrible, but they’re not optimal. Maybe someone with more information could disect this one. I usually do something like min -3, max -1, hsph: 80, interp: 30.
Your DMC Noise threshold is VERY high (like insanely high quality). Set it to: 0.007, and your adaptive amount to .85 (the default) and show us what you get please.
Also turning on “use light cache for glossy rays” should improve your rendertime as well.
That sample rate element is your AA Sampler, not your IMAP samples. Just FYI. Or at least it sure looks like your AA Sample Rate.
I use -3 -1 too, but 80 still gave me blotches. I can try your settings just to see, but I think hsph 80 is not enough for this scene. Also won’t interp samples 30 smooth the details too much? I don’t like increasing it. Maybe I should leave hsph 110 and change clr, nrm, dst thresholds? though I’m not good with those.
Here is what hsph 110 looks like. The left dark wall with plants is still not perfect, but ok.
Could you please send your scene to vray@chaosgoup.com and we will investigate what cause this splotches.
Hi,
In your case, the Global Illumination samples are not enough for the darker parts of the scene and produce splotches, especially when using V-Ray Sky map in the V-Ray environment slot.
We can advise you to lower the “Adaptive Amount” value and increase the minimum samples. This will increase the render time, but the result will be better. As an example we have the attached render with settings: Adaptive Amount (0.45); Min. Samples (30);
Note that V-Ray 2.0 has many improvements in this area, you can find more information about it at: Chaos: Industry-leading design and visualization software
in “Changes to the Adaptaive DMC” part.
