Hi,

I 'm finishing a scene which has a volumetric spotlight as a main light source. Now if i do a test render in Preview or Final Mode, the rays from the light are really grainy.

I know i can boost the 'Quality boost' in the light tab and the atmosphere tab, but are there specific amounts of boost ? Or other render settings to take into account (i 'm still a bit of a render newbie when it comes to render settings)

I want to render the scene in Global Radiosity and the scene is located in a dark place. Maybe some extra gain settings here ?

Thanks
Wim

Up the quality boost of the volumetric lighting to 7 or 8 then give it a try, higher numbers less grain but longer render times ofc.

Jon

I usually have the volumetric quality boost set to 2 or sometimes 3 - gives nice smooth volumetrics.  When I'm using GR, I often set the quality slider in the lighting tab of the atmosphere editor to -1.  Speeds up the render hugely and doesn't have much (if any) impact on the quality of the render)

I never had much luck on volumetric that low, to get no or vrtually no grain I had to go a lot higher. I guess the best thing to do is just try different settings.

Jon

Doing a small test currently with the light quality boost set to 7 and atmo boost set to 2.
Only rendering about 1/10th of the image in Final Mode with a 'area selected render' which contains lots of light.

So far Vue 'guesses' that it will take aprox 5 hours to render this part !!

Hmm... setting the atmo boost to a - instead of a + ... will try that later on :-)

Ah ! Just checked how far it was and now it 's saying 'time left 1h19'
Man this time guessing thing is wobbly LOL !!

Yeah I wouldnt pay too much attention to how much time is left, it can vary on what part of the scene it is on.

Jon

1:
Light quality boost +4 and sky-fog-haze boost +2 give me a finished render time of 1h56'42"

2:
Light quality boost +4 and sky-fog-haze boost -1 give me a finished render time of 1h53'45"

I think picture 1 is slightly less grainy but it 's hard to tell.
I said before that i used a quality boost of +7 in the light tab, however the setting changes itself always back to +4 if i check again ???
I can 't oversample this setting (as one can with most of the other parameters).

Wim

Most of the volumetrics in my gallery are done with a boost of 2.  It might be that because the background is black I can get away with it but the volumetrics are normally pretty smooth

You don't need to boost the atmosphere. Bossting atmos is for grain in clouds, godrays, shadows recieved by clouds, and grainy anisotropy.
Simply boost the volumetric light quality. I'd go for 3-4 max, should be enough. Try smaller values first on area renders, and increase the value until you find the quality acceptable. Then do a full render.
This is how I do it anyway.

Just finished rendering the image and yes, still some grain but oh well... shows me how much i still have to learn about Vue LOL

Image is uploaded in galleries if ya want to see :-)

What Bruno said.
Plus, if long render time is unbearable (volumetric beams or clouds, etc.), forget the grain in Vue and fix it by post-processing in "Neat Image" - a wonderful photographer's noise and artifact reducer.

Actually, after posting the image onto Rendo i was playing with it again in Photoshop and applied a smart blur to it very softly, and that also fixed the grain away.
Should have done it before posting the image but i did not think of it at that time.

Thanks for the link, i never heard of that plug-in before :-)

My godrays renders are grainy. What should I set to what? Thanks

I would suggest what i did and first make area renders before you render the whole image. Probably with godrays i would think you have to give a quality boost in the sky-fog-haze tab and maybe also some quality boost in the lighting tab.

Keep in mind the large render times when upping these boosts ! As you can see on the two examples i posted and the render time that came with them :-)

I can 't say what is better for this, volumetric or spectral mode because as i said before, when it comes to render settings i 'm still somewhat of a newbie LOL !

With godrays, you really need to boost the atmo quality in the sky, fog & haze tab. This forces Vue to supersample cloud functions. A quality boost of one will double the render time of the atmosphere (not the whole render), so boost the quality little by little and make small area renders of the problem areas to save you some time. Once you're happy with the quality, do your full render.

...and if render times get excessive, Neat Image is a good solution (see above link).

I tried Neat Image a while ago.  I found it blurred everyting else too much.  I s there a knack to it that I missed ?

It's not automatic - or shouldn't be used that way. Something like this:
Remember that it can work stand-alone (how I do it), or as a Photoshop plugin (I think)
It uses artificial intelligence, so the results depend on how/what it samples.

1. Load your image

2. Use  "Device Noise Profile" tab. Use (drop list - "..Auto with calibration target"). It will do some processing. You can move the "target" square around and re-process (use the big "Auto Profile button, not it's drop list). On the right, I set the noise profile to RGB as the "working color space" - this will cause a reprocess. You now have a "Rough Noise Profile" to work with.

3. Fine tune it: Go to "Noise Filter Settings" tab and click on "Preview". Zoom your image larger if you like. You get a square where the final result will show. Move it around to check different parts of the image, while you adjust the right panel controls for "Noise Reduction Amounts. Set all levers to zero, then start with the high frequency (smallest "grains") noise and adjust up from zero until you get rid of the grain without blurring the image (typically 50% to 75%).

If you still see larger "grain" do the same for the mid frequency and maybe the low frequency. Don't do any more than necessary, if you want to keep a nice sharp image.

If most of your noise is in just one color channel, you can control that as well.

1. When you're happy, save your image with the "Output Image" tab.

As usual, a detailed explanation makes it sound harder than it actually is - once you've done a few images, it becomes very quick and easy. 

Of course, they have a help system. so RTFM.

Thanks for the tips. Made a note of it if I still have the demo on my hd.

I did rtfm several times over as I recall but success eluded me !

Yeah, maybe the trick is to be sure to view your image at 100% zoom (doesn't do that by default), while adjusting those noise reduction sliders (from zero)  and carefully inspecting the preview marque.
 
It's pretty easy to overdo the noise reduction.