Detailed Car Paint Flakes

[leehenshall]

I'm looking at improving my car paint workflow. After using products like Renderman and Vred I noticed that their car paint solutions are quite nice. They use normal maps to offset the reflection direction slightly to create that nice metallic paint flake appearance.

https://renderman.pixar.com/forum/do.../pxrFlakes.php



Renderman uses procedural circles that are applied via a normal map



vRed uses a slightly different pattern which also looks good







It looks like procedural layered diamond patterns and is quite effective

I find that Vray flakes are not the most intuitive or easy to preview flake solution on the market. Most Automotive artists I've worked with tend not to use the Vray Carpaint material.

I normally make my own blend material setup with a flake texture mapped into the specular of the base material. But looking at these simple bump mapped solutions I think I can get a better result by using the above techniques.

More recently I've discovered OSL flakes which are remarkably similar to the Renderman option.

http://docs.chaosgroup.com/display/O...es+normal+map#

It does everything I want it to except work as a tri planar projection. It feels quite limited because it seems to rely on UVs to get its texture coordinates. That would be fine for a simple model but it's usually too much work to unwrap every CAD body panel especially when you want to reuse the shader and still keep the look consistent.

Using the complex IOR OSL combined with OSL Flakes I think a very realistic paint is possible. I'm sure it might come with its own AA sampling issues but maybe some work could be done to improve how vRay produces procedural flake effects?

It would be great to learn more about other peoples setups and discuss.

[leehenshall]

To get things started here's my base setup:



Result:



The main thing I need is a good procedural bump to break up the highlight.

carPaintBaseSetup_v001.zip

Added OSL Flakes



Shader Preview

[leehenshall]

Complex IOR OSL Added



Complex IOR OSL Preview:



I got the N & K values by going to http://refractiveindex.info/?shelf=m...=Ag&page=Rakic

It's all in the vRay documentation http://docs.chaosgroup.com/display/O...resnel+shader#

I used titanium as a base to get something metallic looking then fudged it from there using colour correction nodes. I would like to know how I can get hold of more realistic values for car paint. I guess this will be a difficult thing to generalize. I find it quite hard to get the exact colour I want easily when using this method. I'm not sure how a flipflop style 2 tone flake would be possible using this technique either.

[t.petrov]

More recently I've discovered OSL flakes which are remarkably similar to the Renderman option.

http://docs.chaosgroup.com/display/O...es+normal+map#

It does everything I want it to except work as a tri planar projection. It feels quite limited because it seems to rely on UVs to get its texture coordinates.

This is easily fixable, so I've taken the time to do it and the fix will be available in the next night build.
After some internal testing I'll probably apply the fix to the stable night builds.

[leehenshall]

Great news thankyou for looking into this!

[david m.]

Hi, thanks for looking into this. I'm running into the same issue, any news about that?

[adanmq]

Hi.I´m also trying to create a realistic car paint material in Vray.

I think your approximation it´s not entirely correct, if you use the IOR of the metal from N-K values, you assume the light it´s hitting the metal directly and reflecting on the surface, but it isn´t, the light travels trough the paint before hit the metal fragments and its "tinted" twice (before and after hitting the metal). I attach some examples.


Depending on the painting itself this can be even more complex because the light will go trough multiple layers. But basically, you have to "FAKE" the tint of the light before it will hit the surface in order to control the color property, otherwise, you will always get over bright/reflect material.

If we can specify the thickness of the different layers in Vray it will be different, but we can´t. So we must fake the behavior of light.

I´m still working on nice flakes, the ones i have now dosn´t looks nice. If you have any ideas i will thank you.
This is my material so far:


And some examples:



PD: Excuse my bad English.

[emartin8907]

has the osl fix been incorporated into the nightlies? Just checked the 9-29 readme and found; " [modified feature] OSL: Use the connected placement node, instead of using some defualt - resolved."

going to download and give this a spin!

[vlado]

For car paint specifically you can also check this post:
http://forums.chaosgroup.com/showthr...ght=stochastic

This is for Max only right now, but we do have the V-Ray shader for Maya/Standalone too. It's not a full car paint material, just the flakes layer, but it may be helpful still.

Best regards,
Vlado

[emartin8907]

For car paint specifically you can also check this post:
http://forums.chaosgroup.com/showthr...ght=stochastic

This is for Max only right now, but we do have the V-Ray shader for Maya/Standalone too. It's not a full car paint material, just the flakes layer, but it may be helpful still.

Best regards,
Vlado

this looks awesome! How do I make use of it in maya/standalone? Can't wait for it to be fully ready for Maya

[brobins]

Would it be possible to try the Maya shader for this?

Many Thanks,

[vlado]

Get a newer nightly build and go to Create > V-Ray > Create from V-Ray plugin > BRDF Material > BRDF Stochastic flakes. We don't have a separate AE template yet, so the UI will be auto-generated. Let me know if you have any questions.

Best regards,
Vlado