noise just wont go away..?

[super gnu]

ive gt a scene lit by a domelight and some selfilluminated materials (small objects) with one bounce of bruteforce gi.


i have had to set up this scene quickly so im using broad fixes to get good image quality.. optimising for rendertime comes later.

bf is on 64 subdivs, aa is on 2/20, domelight with rendered studio lighting hdr has 64 subdivs also. most refs /refractions have 8 or 16 subdivs.


ive got the adaptive amount set to 0.85 (and ive tried at 1 too.), and am using the noise threshold and global subdivs multiplier to try to get a clean render.


strangely enough, it looks quite clean in most areas with a subdiv multiplier of 3, and a noise threshold of 0.003.

however a few areas are still really grainy (mainly ones lit by /reflecting the small selfilluminated objects)


and ive found even turning the noise threshold to an insane 0.001 and global subdivs up to 15, it doenst seem to get any cleaner.. both gi and reflection render elements are really grainy in those areas.

finally i turned the global subdivs up to 100 just to see, and it looked worse! and strangely had blotches a few pixels across..

needless to say rendertimes were ugly too.

[peterguthrie]

have you added all the relevant render elements to try and see where the noise is coming from?

also, do the self illuminated materials need to be casting light? maybe put them in a vrayoverridematerial and add actual vraylights instead?

[Morne]

try lowering the adaptive amount instead of increasing it. For a test, change it from 0.85 to something like 0.2

[joconnell]

Do you need aa of 2/20? Is the scene light enough to upload?

[super gnu]

thx for the suggestions..

peter, ive seen the noise is present in both the gi and reflection render elements...

i want the light objects to emit light as there are 100's of them and they will all be animated changing in intensity probably controlled by a map. .. since rendertimes are generous (its only 250 frames long) i can life with the penalty rather than having to animate a matching set of lights.

im sure this could be scripted or done using parameter wiring, but it seemed simpler just to use single bounce gi. its also actually much faster (for some reason) than using the vraylight in meshlight mode..

just surprised i cant clean up the grain -no matter how high- i put the settings.

but, possibly Morne may be onto something ( although i did try increasing the min-samples, which should have a similar effect to reducing the adaptive amount...didnt have much effect, although i didnt test thoroughly. ill give your suggestion a shot later and report back.

[joconnell]

Pop up a few rendered frames showing the problem with your sample rate element.

[super gnu]

Jo.. i probably could use less AA, its all about clean materials and lighting in this one, its a product shot..

ill have to ask my client if i can upload a piece of the model, as its probably confidential but wouldnt be identifiable...

[joconnell]

Sure - maybe swap out the model for something else but retain all the materials / lights? Teapot in the place of the main subject? Is the object complex in terms of geometric or texture detail? I reckon it's the AA undermining your lights and materials.

[super gnu]

ahh should be ok to sent the model its only a piece ive worked up at the mo.. a test really.

i suspect the thing causing the problem is the leds along the bottom, a row of 50 ish, most green with a few yellows and reds.. (its a graphic equaliser) those being reflected in a rubber surface.. looking at the sampler rate and reflection elements its having issues... but its the fact that i actually cant get it clean at all, that is the key. im rendering a crop with those renderelements to comment on. be about 25 mins.

[joconnell]

Great - the render elements will tell a lot.

[super gnu]

there you go.. that crop took 30 mins on my 6 core.

to be honest its probably good enough as it will be flown past quite quick with moblur and dof.

but i still wanna know how to get a totally clean render..

look at the central un-illuminated button, the green reflection on the bottom is the most grainy bit.

specific settings for that render were:


aa 2_24

blend aa filter on very very low setting, 0.003 to get a slight glow to lights and highlights.

bf gi on 64 subdivs

adaptive 0.95

noise thresh. 0.004

min samples 64

global subdiv mult. 5

higher settings dont look any clearer really and rendertime just goes up and up. rendertimes are about the highest i wanna go, considering i wanna add dof.. although i might go with lenscare for that.. dof'fing those glossy refractions is asking for trouble..

[joconnell]

What I reckon is that your AA is way too high for something that's so geometrically simple. I'd go with aa 1/4 or 1/8, unlink the use dmc threshold and leave it at 0.01 or even 0.02 (maybe check with a grey override to see are your edges clean enough) so that you get more samples coming from your material and lighting. Adaptive 0.9 is my normal amount. I'd leave your dmc noise threshold around 0.01 for the minute - you might need to go down a tiny bit but not near what you have. I'd set your minimum samples and global subdivs back to normal too. The noise is your lighting and your material trying to reflect your lighting. I'd up your glossy reflection samples up a good bit and quite importantly turn down the reflection bounces as the material gets more glossy - they won't contribute much extra but will slow things down a lot. Try that to start!

[super gnu]

check your PM. i tried your suggestion but i got more noise and longer times it seemed.. i tried a range of subdiv levels ( globally changing them using VMC im afraid, pita to adjust them all.. those glowy buttons have quite a fiddly material setup. ) but couldnt get a better result.. i often find i get better results relying more on the aa engine, even if it seems i shouldnt.
btw i am using the embree plugin, seemed to cut a bit off my times but very little really.