Vray Interior Grain - Please Help!

[jodonnell]

Hi all.

 

I have set up a scene and rendered out perfectly acceptable results (attached).

 

I then removed the geometry from the scene, imported my new model (I model in AutoCAD) and applied the same materials, used the same lights and the same settings.

 

I'm getting a really grainy effect on all of the surfaces. I have tried playing around with various indirect illumination settings including photon samples and various image samplers, antialiasing filters, subdivision on the lights and so much more!

 

Playing around with the image sampler seemed to reduce the results but I'm fairly new to Vray and am self-taught so I'm not sure which settings I should change to get rid of it. Any help would be greatly appreciated.

 

I tried using an irradiance map on the highest preset and that just gave my blurry blotches instead of sharp ones!

 

The only change between the two scenes is a new material for the carpet which uses displacement, but I've tried taking that off and it has no effect.

 

Scene setup:

 

1 x Direct light

IES lights in physical positions

 

 

Settings are:

 

Adaptive Subdivision

Min 1

Max 2

Clr thresh 0.1

 

Primary

Brute Force

24 Subdv

 

Secondary

Light Cache

1000 Samples

Sample size - 0.01

Scale - Screen

 

The grain appears in the pre-pass and then just gets "dimmed" on the render pass.

 

Rather than just change numbers which I don't understand I'd much rather learn what's going wrong so I can fix it myself next time...

 

I'd appreciate any help you can offer

 

Thanks,

 

Jamie

[Dave Buckley]

in the render setup dialogue for vray, choose the settings tab, then there should be abutton towards the bottom that says light settings, clik that and then for each light in your scene change the diffuse subdivisions, the default is around 150, stick another 0 on the end

 

also for each material that reflects regardless of how strong the reflections are, the subdivisons of reflection and refraction need to be upped to a suitable amount for the materials

[Nic H]

hmm I wouldnt delve into the light settings to be honest, no need to.

 

Put your primarybounce on IRMap, secondary on LC

 

Start with low preset but with (-6,-3) for IRR, LC on 1000 / screen mode (use LC for glossy ticked) work up from here if needed.

 

For a scene like this with glossies, use DMC sampler, start at 1/4 and work up from there to prob 3/6 for final?, you can adjust clr threshold in the DMC sampler down to reduce fine noise, i dont think you would need to go lower than 0.005 for this scene (default is 0.01, chuck it on 0.1 for quick tests)

 

That said there are heaps of variables to consider and what works for one scene may not work for another etc. best to learn inside out and adapt what you learn to different jobs - or do quick test scenes and learn a few bits.

[Dave Buchhofer]

I'd lean with Nic.. unless you're doing object animation i would rarely reccommend using brute force for primary bounces.. it CAN look good using brute force, but it'll sure as hell be slow

 

If you DO stay with brute force, switching over to a DMC image sampling, and tweaking the color threshold in there DOWN (guess: 0.006) and the max rate up.. 5-6.. would smooth you out without having to get too crazy.. and if you have any number of glossy reflections, it might even be faster than your current adaptive subdivision type.

[jodonnell]

Cheers guys...

 

Yea, increasing the diffuse subdivisions of the lights made no difference. I've now switched over to an IRMap with the settings nicnic suggested so I'll keep you posted on how I get on.

[fadi3d]

Hello Guys'

i Freequently run into the same Problem and i have to agree with Nic and Dave Buchhofer. But i Read somewhere that using DMC we rarerly need to set the Lower for more than 1. Do u agree ? and why ?

i usually for this kind of Scene go for 1/20 and a Clr thr 0.005 am i doing things Wrong ?

Cheers

[CRD]

You should also check the scale of your new acad import. A lot of the physically correct settings are size dependent.

 

I would also recommend the switch to IRmap + LC and if you have the time, turn on the Detail Enhancement in the IRmap.