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Let there be some metallic flakes!
让我们来点儿金属烤漆效果~
英文不好的同学就自己开google翻译吧 今天天冷 手冻木了不打字翻译了
It seems like CG artists always want to render cars, the amount of actual iray user scenes we get that are cars is remarkable. It’s like a fundamental constant of the universe. So if a renderer cannot do cars it’s useless for a German. Luckily iray is quite good at rendering cars… but of course there is always room for improvement.
For iray 2.0 we focused on the features of our internal material model a lot and it has become pretty powerful: it allows flexible layering of BSDFs. So creating a basic car paint becomes a relatively intuitive task. We start with diffuse base layer, mix in some glossy BRDF, and create a Fresnel-blended clearcoat layer on top of that, done, the simple carpaint is finished.
But that’s relatively boring, we might want a carpaint with metallic flakes for the simple reason that metallic paints look cool: iray 2.0 also features a built-in procedural to create flakes, it is a layer modifier that affects the layer just like small flakes in the real world would do. The behavior and the parameters are essentially the same as for the mental ray metallic paint shader: we can change flake size and density and the how much the flake orientation is allowed to differ from the surface normal.
So going back to the simple carpaint, we just add one layer in between the base and the clear coat layer and apply the flake procedural. For standard metallic paints we can use a perfectly specular or very glossy BRDF in that layer to mimic the high specularity of the flakes. Here’s the result:
We have the possibility to create very small flakes which, from a distance, behave like a glossy BRDF (the flakes play microfacet!):
or we can create fewer larger flakes which give the nice sparkling effect you get from pronounced metallic paint:
Playing with the flake layer color and the flake parameters, we can now create all kinds of metallic paints, from family cars to pimpmobiles! Here is our blue metallic paint with the addition of a second, green flake layer on top:
Stay tuned, there will be more on what the new material model can do in future posts, this is just a first example of new functionality.
PS: All the images above are fully converged, any appearance of “noise” is actually the metallic flakes doing their thing
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