Texturing and the different maps

This information is taken from modwiki; This information will be very useful to me as i have nearly completed my textures for the exterior and will definatly look at this for refrence and guidelines to help me.

Diffuse maps
Diffuse maps in Doom 3 represent the diffuse reflection and color of a surface. In other words they define the color and intensity of light reflected back when it strikes a surface.
The goal when creating a diffuse map is to draw a color map and darken areas where light would be absorbed. For instance, the cracks in a brick wall absorb more light than they reflect back.
The example to the right demonstrates this as the bricks themselves are a greyish value and the cracks between them almost black.
No surface reflects light back at the same intensity it's recieved. In that respect, it's a good idea to darken your diffuse maps appropriately. Generally, the smoother a surface is the less light is diffused and the brighter your diffuse map can be.
Diffuse maps are added to material shaders by use of the Diffusemap keyword or the Blend keyword with the "diffusemap" parameter. As convention it's recommended that you add "_d" to the end of the texture's filename.

Bump maps
Bump mapping adds an illusion of depth and texture to images. It doesn't actually alter geometry but rather affects the shading over a surface. There are two different kinds of bump maps useable in the Doom 3 engine: Normal and height maps.
Normal maps
Normal maps define the slope or normals of a surface. In other words, they alter the direction a surface appears to be facing.
The normal for each pixel is defined by storing spacial X,Y,Z transformation data in the R,G,B channels. The example to the right demonstrates this.
There are two methods to create normal maps.
Render a normal map from 3D geometry
Convert a height map into a normal map
There are links to tools for use with both methods at the bottom of this page.
Inverting the green channel of a normal map.
Depending on the tool used to render normal maps, you may need to invert the green channel of the resulting image in order for your normal map to render properly in game. When viewing the green channel of the image, it should appear as if it's being illuminated from the bottom.
Normal bump maps are added to material shaders by use of the Bumpmap keyword or the Blend keyword with the "bumpmap" parameter. As convention it's recommended that you add "_local" to the end of the texture's filename.

Specular maps
Specular maps in Doom 3 represent the specular intensity and color of highlights on a surface. In other words they define the "shinyness" and color of specular reflections.
The brighter a specular map is, the more shine is applied to the final material.
The goal when creating a specular map is to fill the image with a solid value to represent the general specularity of the surface and then darken areas where weathering would occur.
The example at right has a mistake; the face of a brick would recieve less wear and tear than the edges and should therefore be more specular. Note that the cracks themselves have little to no specularity at all.
Color applied to a specular map tints the color of highlights. Bricks are made out of a sand like material and as such would reflect slightly variable tints. This too is present in the example to the right.
Specular maps are added to material shaders by use of the Specularmap keyword or the Blend keyword with the "specularmap" parameter. As convention it's recommended that you add "_s" to the end of the texture's filename.
Bump maps can be modified into a good starting point for a specular map.

http://www.modwiki.net/wiki/Texturing 19:20 Wedenesday 11 February