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Advanced Material Room- The Alternate Channels

For use in Poser 7 as well as Posers 5 or 6

Been wondering what alternate_diffuse and alternate_specular are for? Been wondering what alternate_diffuse and alternate_specular are for? You've come to the right place here.

The purpose of these channels is to allow you to replace Poser's standard BDRF with alternatives.

"What's a BDRF" you ask? BDRF stands for Bidirectional Reflectance Distribution Function- BRDFs are more or less complex equations that tell the renderer what a surface looks like, depending on viewing direction, light direction, surface color and maybe a few other parameters.

Why all the fuzz? Aren't textures sufficient to make a surface look like any material? No, they aren't. A ping pong ball, paper or a white car have the exact same color, but they don't look the same.

What do we Poser users gain from different BRDFs? We can get rid of that "plastic" Poser 4 look...

How we use those BRDFs? First, let's start by deactivating the standard Poser 4 BRDF (which, by the way, is a so-called Lambert-Phong model). Set the diffuse_value and specular_value to 0.

Done that? OK, so then I'll tell you what BRDFs we have and where to find them: They're all in the "lighting" department, in the categories diffuse, specular and special. As you may have guessed, the diffuse ones go into alternate_diffuse, specular ones go into alternate_specular. The special ones? Put them in alternate_diffuse too.

Enough theory! Get to the point!

OK, let's get to some pretty images.

Load three ball props and add a single white directional light.

Then go to the Advanced Material Room and edit their materials: for each ball, set diffuse_value and specular_value to 0 and give them nodes for their alternate_diffuse channels: One gets diffuse, one gets clay, one gets toon. On the clay node, set the roughness parameter to 0.6.

Now render.

OK, so diffuse is a little boring. It's basically the same (Lambert) shader as the P4 standard. In Poser 5 it has the advantage of being less likely to have artifacts with double-sided polygons, an effect that on Poser 6 can be disabled and enabled with the "normals_forward" checkbox.

Clay is more interesting, because it behaves not just like plastic (clay is a Oren-Nayar shader, for you 3ds users). The roughness parameter can be used to change its character.

Toon - well, the name says it all: Toon.

Try our specials!

Here's skin, velvet and hair, from the Special category of Lighting nodes - all set to white.

Note that here we got two lights in the scene, I added a backlight to enhance the specific looks of skin and velvet.

Hair doesn't look to good on a ball, so we'll keep that one for dynamic hair, where it looks much better.

Not bad for a start - all of these are white, but look completely different!

Now for alternate_specular:

These are Blinn, Glossy and Specular nodes attached to the alternate_specular channel (ball_1 gets Blinn, ball_2 gets Glossy, ball_3 gets Specular), in combination with a Clay node on the alternate_diffuse channel. Note that this is just the look with the default settings, you can change their looks by playing with the parameters.

All of these are clay & blinn, only with different settings for the blinn parameters.

Did you ever wonder what anisotropic is good for? It's for non-circular highlights, like you see them for example on brushed metal surfaces. To achieve that effect, set the u_highlight_size and v_highlight_size to different values.

Final treat:

Use a color_math node, set to add, to combine multiple specular highlights. Give them slightly different colors, and you can get a "finish" look.

Thanks and kudos to Stefan Werner, the original author!