Question about map types

[swag]

I was just curious, but I couldn't seem to find much info on these two maps. Figured it was best to ask here anyway, especially if someone else has these questions.

Does anyone know what a 'Specular Gradation Map' is for? I know what it is, based of the name, but why would you want to apply specularity in a gradient form?

The other one is a 'Incidence map'. Is this just a glow map?

Thanks.

[Talon]

Specular Gradation Map sounds like it might be another name for a gloss map.

Incidence map... I don't really know. Could be something to do with a fresnel falloff or refraction?

Where did you get the names from?

[swag]

Sorry, I should have posted the article where I got them from. It's from CGSociety's Metal Gear Solid 4 feature.

CGSociety - Metal Gear Solid 4: Guns of the Patriots

They are using XSI, not sure if those are just the unique names that it uses.

[virtualalias]

As far as the Incidence Control Map, this was said in another forum:

Originally Posted by Twindragon

Well the incidence in XSI Shades the edges of an object or defines an arbitrary shading direction based on light or on the angle of the surface relative to the camera, one or more lights, or a vector. This is useful for fresnel reflections and effects like xray effects. The map they have probably makes it so you get glancing colors of blue on the edges of objects from the sky and the map defines where it will show up the most.

It looks like Talon is correct, or at least has some back-up!