I'm sure this is a quick resolve...

[erikpilon]

Hello friends, and new found family!

 

First time poster.

 

I have moved from Mental Ray to Vray yesterday, yay !

 

Learning it is so not as complicated as I thought. But I'm having the same issue for the same scene as I had with Mental Ray...

 

Attached is the rendered picture, I think Vray goes over the rendering 3 - 4 times, and the 2nd last pass of rendering is perfect, then it goes ahead and does another final pass, and this grain shows up again. Sadly.

 

Working in linear (not affect color, 2.2 gamma, work in linear, etc.), cranked up the Sun's Shadow Subdivs to 96, Primary Bounce is set to Irradiance Map at "Very High Quality" at a Subdivs of 600 (800 looks exactly the same), and clicked on "Enhance Details". Secondary Bounce is set to Brute Force, Subdivs 32, Depth 3.

 

I'm starting an architectural walkthrough project next week, and I think this is the only question I need resolved to accomplish future projects...

 

Thanks a bunch friends!

[erikpilon]

Note to self, don't use Skyportal.

[Corey Beaulieu]

It probably is a simple resolve, but there is much needed information before you will get your answer.

 

What is your lighting setup? Is there glass in that window? What is the material setting? Are you waiting for the final render before considering the render (this looks like a light cache)? Are you using Vray lights?

 

Skylight portals can help interiors, but as discovered they can also add noise in certain situations.

 

Your render settings are ridiculous. Irradiance and Brute force are not normal render choices and 600 and 800 subdivisions is obscene for a simple render like this. For any render really. Also Very High = Very New to rendering.

 

I know you said you are learning, so maybe start with the following:

 

- Use Vray Sun/Sky. Place a sky map in the Environment Override Rollout of the Vray Settings and Instance it to the GI slot and Reflection. If you want a smoother shadow gradient on your sun, the subdues are not too important, you can use 24 or less, but increase the size to 5 or 10. Sharper shadows use lower values in the multiplier.

- Use glass in your window and in the material setting make sure that Refraction has "Affect Shadows" ticked and that the drop down menu is set to "Color+Alpha"

- Primary Bounce = Irradiance Map; Secondary Bounce = Light Cache.

- Use Medium for Irradiance and set the HSPH to 70 and 40 for the Interpolation. Don't bother with "Enhance Details"

- For your Light Cache you can use the width of your image as the subdivisions up to, say 2000

- If you use a SkyPortal, be sure it is a vary plane light set camera side of your glass and tick: Skylight Portal. Don't use simple and I would increase the subdivs a bit.

 

I'm sure I've missed something, but these are the basics to a Still Image. Animations are different. Brute for with Light Cache for Moving objects; Precalculated Irradience (Multi-Frame Incremental) and Light Cache set to Fly Through… It's complicated. Check out this tutorial: http://help.chaosgroup.com/vray/help/150SP1/tutorials_imap2.htm

 

Anyway. I hope this helps. Vray is full of settings,but it generally works fine without a lot of tweaking.

[erikpilon]

Thank you very much for your help.

 

I figured the settings were too high by the render time, but I cranked up everything on purpose to see what was the exact problem, and even with everything on high, the problem still happened.

 

There was no glass in my windows, but after putting one, I noticed the lighting decreased dramatically, still need to play around with that.

 

Looking at the link you sent me for the walkthrough now, hopefully after paying for a render farm I won't end-up seeing that flickering people keep talking about. Will see how things go!

 

Again, thank you Corey.

[inpow watir]

Have you check DMC noise threshold? As it could also generates that kind of grain you have on the attached render output sample. (It can be set on v-ray tab and/or global setting depends on what vray version you have). Try to make it lower e.g. 0.02, the lower the value the longer rendering time. You'll figured out the ideal number suited to your expectation by experience. Goodluck.

[erikpilon]

Yes, DMC noise threshold has been at 0.02, it really was the Skyportal, even at 32 samples, the grain would just move position...

[jasonstewart]

Noise threshold of .02 is very high. I would suggest .01 as your default value. This will change the sampling of everything in your scene including lights (or the sky portal). If when it is calculating it sees a difference of less than .02 and has used the min amount of samples governed by the adaptive amount then it will move on. So what you are doing is telling it you want .02 or less noise, you have cranked other settings but in reality it is not using all those samples because it is reaching the noise threshold.

 

For the subdivision amount on the sky portals. You can get faster renders with more subdivisions in the case that the AA sampler is cleaning up noise from the sky portals (or anything for that matter but in this case sky portals).

 

For a beginner I would suggest a very basic approach at first, use universal settings or a slight variation on that. From there you can slowly learn each layer of vray and gain extra control.

 

Are you using vray 3.0?

[inpow watir]

Hi Jason, actually you suggested an even higher setting :-P

 

Erik, as for vray plain skyportal light, have you learn how to place them properly? (SkyPortal light should never be blocked by any geometry in front of them to avoid such noise similar to the grain you have there). You could find a lot of tutorial for the proper placement of skyportal light on youtube.

[jasonstewart]

Hi Jason, actually you suggested an even higher setting :-P

 

Erik, as for vray plain skyportal light, have you learn how to place them properly? (SkyPortal light should never be blocked by any geometry in front of them to avoid such noise similar to the grain you have there). You could find a lot of tutorial for the proper placement of skyportal light on youtube.

 

He complains that even with super high settings (that no one would use in production) he is still getting noise. This is because his noise threshold is too high. It is stopping all calculations early because it has reached the noise threshold.

 

This is why I suggest to start out with Universal Settings. It almost guarantees a usable image with a small sacrifice in render speed. From there he can start playing with settings to see the effect but have a solid base to go back to if the results are not good.

[inpow watir]

Noise threshold of .02 is very high. I would suggest .01 as your default value. This...

 

I'm refering to that (quoted). As numbers figure yes 0.02 is higher than 0.01 but we are talking about threshold here. Are you sure the quality result from 0.01 noise threshold is the lower than 0.02?

 

The smaller = the higher (edited)

 

Your logic was upsidedown and might confuse TS.

Edited September 17, 2014 by inpowwatir

[jasonstewart]

I see what you are saying. I meant the number was high but is not enough and less is more? Hard to say I guess. Since it is a threshold for noise you could say that a higher number allows more noise (it does) so it is too high.