Vray car paint setup thoughts

[seandunderdale]

Hey guys,

Is there a specific method for incorporating stochastic flakes into a car paint shader? Currently we use a blend shader, with a car paint set to base paint only, in the base of the blend. Then we drop a stochastic flakes above that on 50% blend (sometimes an inverted fresnel so the flakes are showing more on the facing side). Then we have a gloss coat on the top of those using a standard vray fresnel the blend.

When weve used this to match to location shoot stand-in cars its done pretty well, but we have been wondering if anyone can shed some light on an official way to use the stochastic flakes.

[yolov]

I had forgotten that we prepared a tutorial specifically for that and I forgot to publish it. I'ts public now: https://docs.chaosgroup.com/display/...asticFlakesMtl

There's also another one for snow, that's been there for a while: https://docs.chaosgroup.com/display/...asticFlakesMtl

Both are for 3ds Max, but this is valid for Maya as well. We usually suggest the same - blend with a falloff. It makes some difference if the flakes are the base or the coat of the blend. It can be both, but each will give either a more diffuse or a more reflective result.

[seandunderdale]

Nice one Yolov. The setup in the doc is almost the same as what we are using which is reassuring. We will test out the second flake layer option and see where that gets us. Thankyou very much fella!

[SonyBoy]

Should the blend materials be set to Additive? The tutorial doesn't mention this but I am assuming that's the case...

[seandunderdale]

We never use Additive for anything. I wouldn't suggest using it for car paint.

[yolov]

No, I'd also recommend not using the additive mode of the blendMtl for this.

[seandunderdale]

Can I ask where you got the base fresnel value from? 14.0 seems high considering we use 6.0 for chrome.

[yolov]

We just wanted to have a very reflective base material and just coat it with two layers of flakes. There's no particular reason beside the look that we were after.

[seandunderdale]

Thanks Yolov. The added info has made a noticeable difference. Feeling pretty happy with the results now.

One thing I'm still having an issue with is the render times for close up flake. I can get a result that looks good, but the render times sometimes double or triple when the flake "noise" is visible. Is that expected behaviour because of more need for sampling? Or is there a way around it?

To get closeup flake visible I'm dropping the amount down to 1,000-ish and tweaking blend amounts and flake scale to 0.05-0.07.

[yolov]

Can you get me an example scene for the close-up that I can look at?