Surfacing - Blender Foundations: The Essential Guide to Learning Blender 2.6 - page 165

that has no materials assigned to it, the selector window will be
blank, and a large button that reads New is displayed. LMB click it
to add a new material to the object.
LMB clicking on the Material icon (the checkered ball) to the left
of the material's name—“walls” in our example—allows you to
choose any material in the current file. In case you want to remove
a material (unlink it from the selected object), just click the “X”
icon to the right of the name.
Below that management panel is the Preview panel. Blender's mate-
rial preview renders live as you make adjustments to your settings. It
uses Blender's actual internal renderer—no tricks—so you can be sure
that what you're doing in the panel is what you will get in your scene.
By clicking on the icons to the right of the preview, it can be set to
show a plane, a sphere, a cube, a monkey, hair strands, or a larger-
scale sphere with a sky background. In general, you'll choose the
preview object that is closest to the actual one you are surfacing in
your scene. In the case of the example, we are working on walls and
a floor, so the cube (or the plane) is an appropriate choice.
Continuing down the line, we come to the Diffuse panel. Diffuse
refers to the general shading properties of the surface—that is, the
actual way that incoming illumination is dealt with. There are a
number of ways of making these calculations in 3D, and Blender
allows you to select from several options. Each is appropriate for
different circumstances.
● Oren-Nayer is the best for most nonglossy surfaces.
● Lambert is appropriate for shiny metals and plastics.
● Minnaert is good for lush fabrics.
● Toon and Fresnel are special-purpose shaders that won't play
a role in the vast majority of projects you do.
The Web Bucket has examples of each of these. The differences are
sometimes subtle, but it is inaccuracy in the subtleties that can ruin
your scene.
Here's the first place where you'll have to exercise some discipline.
Most of the work you do will almost certainly require Oren-Nayer
and Lambert shading. Don't use the other ones “just because they're
there” or because you suspect they might be lonely.
Observing any number of interior walls, you'll find that unless they are painted with a flat finish, they do
exhibit a certain amount of gloss. While the Oren-Nayer model would be okay, we'll go with Lambert
(the default) because of the slight glossiness.

Figure 7.1 The Materials context.