Tutorial: How to make metallic car paint.

[Knut]

We want a shader that can simulate the two highlights that this type of paint gives. One broad and saturated from the pigments and metal flakes, and one small and hard from the shiny surface of the car paint. To get two highlights, we need a shader that supports this. In max this is called Multi-Layer. Create a new material with multi-layer selected in the shader basic parameters dialog.

[Knut]

When you look at a car with metallic paint it has a different colour when the surface points away from you. To achieve this effect we need a fall-off map in the diffuse slot. It needs to be set to fresnel fallofftype to simulate what’s going on. The brightest colour is on surfaces that are not perpendicular to your line of sight. In the front slot we need a bright but saturated colour that is to your liking. And in the side slot we need a darker version of the same colour. (In my shader I actually put a noise shader in the front/side slots, this simulates the grainy feeling of metal paint. The front noise map consisted of two light reds and the one in the side slot consisted of two dark reds).

[Knut]

The small hard specular highlight are made in the First Specular Layer in the shaders basic parameters. The colour needs to be the brightest of all your colours in this shader (and of course in the same hue). This specular highlight is hard and bright so I set “levels” to 150 and “glossiness” to 97.
The broad and saturated highlight is made in the Second Specular Layer in the shader basic parameters. This colour is quite dark but lighter than the background, so you'll have to adjust while watching the sample window. This highlight is quite bright but not as bright as the first highlight. “Levels” is 100 and Glossiness is 50. On this highlight I set anisotropy to 20 to make it look as if it reacts to the orientation of metal flakes in the paint (not sure if that is true, but who cares, I think it looks better).

[Knut]

Reflections usually make the difference between boring and good. So we need to reflect something. To make this look something near real (or good looking) we need to have a falloff map in the reflection slot. Real materials reflect more as they become closer to your perpendicular line of sight. The fallofftype close to the real thing is called fresnel. The front slot should be left black, but your reflection map goes in the side slot (I used Lakerem.jpg). The bitmap needs to be mapped as a spherical environment.

[Knut]

This is not meant to be a step by step guide and not 100% accurate in every step. But I think everyone will get something out of it. It shows that max has some good shaders to work with, but we still rely on your eye and creativity to create the product. So if your result is not like you had hoped for then you must analyse what’s wrong and adjust accordingly. My colour values can be grabbed from the attached pictures.

This was my first ever tutorial posted online, hope you find it useful.

[Knut]

This is the light red noise map from the diffuse-->falloff-->front slot in my material:

[Knut]

This is the dark red noise map from the diffuse-->falloff-->side slot in my material:

[Knut]

malleus_46 added in a reply some stuff that i now implement in the tutorial. Look in this thread for what he said:

http://www.cgtalk.com/showthread.php?s=&threadid=6725

It's all about the reflections. Standard bitmaps has values from 0-255. But the real world has a far greater dynamic range. So there is a RGBMultiply map in Max. I Added that in the sideslot of the reflection falloff map and kept the old map as a submap. Then i duplicated that map into the second slot in the RGBMultiply map.
Inside the outputproperties of the second bitmap i set "RGB Level" to 6, and left the rest untouched.

Anf that was it. A bit different from what malleus_46 described in his post, but I guess it's up to the artists eye and experience. In the imaged that is atteched i show my original shader to the left, my updated shader in the middle and malleus_46's reflection as described in his post (See the above link to thread).

And a thanks to malleus_46 for input, that is what forums are all about. :thumbsup:

[Knut]

As you can see from the screenshot i have made the lakerem.jpg reflectionmap seamless for spherical mapping. It does look better and you don't get any seams in the reflection.

Knut

[Knut]

Hi, again!

This update on the tutorial adds visible "flakes" in the paint. In the second specular levels slot i added a cellular map to create the metal flakes in the paint. In the following image you can see it's settings. One thing important is that you use supersampling when dealing with very fine details like this. I used the standard max 2.5 star, but the result will be better on expense for rendering time with one of the other like hammersley.

[Knut]

On this image you see the result of the cellular map in the second specular slot. One note on the reflections: You may put a raytrace map or relfect/refract map there to add interaction with objects in the scene. That will add to the rendertime. When i looked at some images of real metallic paint, the grainy effect of the metal flakes are much more pronounced, even in the non highlighted area.

[shoutaway]

Hi Knut
Excellent tutorial. Thanks a lot for that.

Cheers

[IMarshal]

Well done Knut - thanks for sharing it with us.

[boomji]

thats the sharing is caring spirit...keep it up dude
b

[Knut]

Thanks guys!

I've got a few new tutorials or addons to thisone. If i find time for it, i might make some more.

Knut

[shocky]

Hmm... how do you offset the rgb multiply maps?

[Knut]

Hi

I'm not sure what you mean. But you raise RGB Levels in the output properties on your "Multiplier map" (The second slot in the RGB Multiply material).

[shocky]

Ok got it. May i ask where did you get the seamless map, or how do u make it seamless?

[Knut]

I posted a small tutorial on that issue here:

http://www.cgtalk.com/showthread.php?s=&threadid=7887

[vatoloco2004]

[QUOTE=Knut]Hi and welcome to a small workshop on how to make metallic paint.

This is what we want:I would like to know on how to make it and where i could find some of this information.

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