painted metal shader

[ofer]

Hello.

I doing some experiments with metal shaders. I'm trying to achieve a look as close to the Marine's blue armor in the Starcraft 2 cinematic.

I want it to be shiny, and look like it has a wax layer on it, or something like that. But in the same time, I want some wear and tear, like dust and scratches.

I tried the build in shaders but non of them looked good. Now Im working with the car paint shader, after I added some texture nodes to it. But I still don't really get good results.

So while I'm working, I thought maybe someone here can give me a little advice. What should I try, maybe I need a specific light setup? (currently Im just using an environment light, and big white sphere for background and reflection).

Any advice is welcome.

Thanks.

[stu]

I watched the cinematic - there isn't anything fancy happening with the shader - there has just been lot's of paint work. I'd treat something like that as five levels of shading;

1. Bare metal base

2. Paint color.

3. Clear topcoat substrate.

4. Dirt.

5. Displacement.

You'll want to treat each of these as their own lighting model with a texture for each that controls their bleed through to the preceding layer underneath. Each will have their own texture map call for color, specular, reflection, specular and diffuse roughness, etc., etc., or you could manage that level of play between the different materials with a carefully organized photoshop file. Personally I prefer to treat each layer of material (bare metal, paint color, dirt, etc.) as their own model in the shader, that way you don't have to paint multi layered texture maps for esoteric values like fresnel angle and ior. I think that what makes or breaks this sort of effect is whether or not your paint job reflects the geometry (areas that should receive more wear than others are treated appropriately, etc.), that there is some thought behind the relationships between the texturing work in each layer (if there is a section that you're meant to expose bare metal, that the paint color layer and substrate layer are treated in a way that suggests some sort of trauma in the area), and that each material (bare metal, paint, dirt) behave differently and appropriately in the light.

Easy.

[ofer]

Many thanks. I guess that when you know how to look at things, they look simpler. And that is what Im trying to learn here.

So a few more questions:

So do you suggest me to write a new shader, or use an existing one as a a base?

Will the Car Paint shader be a good starting point?

What lighting model you think I should use for the different layers?

When I look at cinematic, I see two main things I want achieve (Im talking about the blue armor):

1. The surface looks like it has a little thick layer of varnish. It just looks like the reflection and spec is not exactly on the paint.

2. The specular lights. There are lots of nice specular lights. Maybe these are not specular lights but actual reflection of the light sources?

Anyway, you gave me a good direction.

Thanks again.

[stu]

1. The surface looks like it has a little thick layer of varnish. It just looks like the reflection and spec is not exactly on the paint.

That's the surface that I referred to as the clear topcoat substrate. You get hard specular reflections over the paint color which in turn has it's own reflections, and in this case the paint looks like it's a metallic flake so the reflections will be broad and paint-colored. Typical metallic car paint.

2. The specular lights. There are lots of nice specular lights. Maybe these are not specular lights but actual reflection of the light sources?

Definitely a reflection map at work here. The magic comes from each material (bare metal, colored paint, clear topcoat substrate, dirt) behaving differently under the influence of the same reflections. When you start to break the shader down, (especially one that can be as complex as this one can be because of the different materials at play), the first thing that you have to ask yourself is how you're going to render it and how the lighting is going to be achieved. Are you planning to use typical CG lightsources or is HDRI a possibility? Micropolygon or pbr?

I'd probably start from scratch (because I'm a control freak and I don't want to hunt bugs in someone else's work ) but you could easily start with something that's already our there.

[ofer]

A daunting task

I think the thing I lack the most is a good environment map for reflections, and good light sources.

I have no idea what kind of lighting to use. I guess that whatever will look good is fine.

Currently I just put an environment light with a HDRI map, and constant white background for reflections.

Thanks.

[ofer]

It is actually fun. I have made some progress. Here is a quick turntable of one piece.

shader1.mov

[stu]

Nice start!

[stevenong]

That looks pretty good. Please keep us posted on your progress!

Cheers!

steven

[ofer]

Thanks.

[Netvudu]

Speaking from the point of someone who has no idea of shader creation...could you share your work so far, or at least a simplified version of it so I can also learn how to layer different shadings in the way commented above?

If you don

Edited October 9, 2008 by Netvudu

[ofer]

woops, I didn't notice this last post at all, until now. I will upload the shader soon.

[Netvudu]

good! that would make a nice christmas present...

plus it would force me to change spending time with my family for trying to learn from your shader...uh...thanks, I guess

[ofer]

Im very sorry, but Im afraid I deleted the shader network. Sometimes I do stupid things like that, and regret afterwards

If I find it in some backup file, Ill post it.

Sorry.

[CinnamonMetal]

Interesting.