Grainy metal - sleepless nights

[tricky]

Does anyone have any good tips for removing the grain from aluminium type metals?

Much of my work is related to warehouses and sheds, and the walls of these buildings are typically profiled metal cladding - sinusoidal/trapezoidal etc.

I have always had problems trying to get a good material for blurry reflections on the metal. If I use interpolated reflections (sub divs say around 50), the resulting render is very blotchy. If I untick interpolated and put subdivs to about 6 or 7, I seem to get a lot more 'control' over the amount of bluriness, but the resulting render is very grainy.

Is it simply a matter of leaving the subdivs at 20, 30 or more (non-interploated) to get a nice smooth metal material? If it is, then my render times go straight through the roof and up into the stratosphere! What other settings should I be looking at?

As far as lighting goes, I generally override the max environment with a very pale blue colour and add one Sun (direct light) with a multiplier of around 1.25, vray shadows and usually use soft shadows with subdivs of around 10. That is it.

Please help so that I can sleep at night.

[TutanMark]

Hi,

USually i don't prefer to use more than 6/7 subdivision for interiors shot, due to excessive rendertime. Of course when i work on details i have to high just a little.

FOr me is a good way to use QMC sampler / Noise threshold = 0.002 or 0.001.

Of course depend on how much grainy metal you want and how many time u have until deadlines.

[cpnichols]

Well dealing with "grainy" things like glossiness, motion blur, DOF, etc... try switching from adaptive AA to two level AA. You will notice the "blochiness" effect will change and may in fact go away.

[tricky]

I've tried the different AA stuff, but it makes very little difference. I have never messed around with the object outline/normals/z-value/material ID parameters though. I wonder if 'Normals' would do anything?

[percydaman]

i doubt it. I just think you need to improve your qmc settings. what are you using for those?

[flipside]

I've tried the different AA stuff, but it makes very little difference. I have never messed around with the object outline/normals/z-value/material ID parameters though. I wonder if 'Normals' would do anything?

AA mathods make a huge difference... If you have lots of glossies, adaptive qmc will be a lot faster than adapt subdiv. Use the std 1/4 settings and set qmc sampler noise to 0.002 for high quality. Use subdivs on your materials from 20 to 30 and you will have no noise at all, with rendertimes being a lot faster than with adaptive subdivision AA.