More surface properties:
Color) This properties depends upon the global lighting in the scene, so it isn't truly inherent to a surface. For example, if a blue ball is illuminated by a red light, it is black to the viewer.
Decal)Also called image mapping. It's the most very basic of surface mapping types.
Bump) James Blinn developed a very simple way to create the appearance of a surface being perturbed (bumped). Today, bump mapping, the use of an image to tell the rendering application what parts of a surface go up and go down, is still a very economical way to add reality and visual interest to an object. The drawback is that the silhouette, the outline of the object is not bumpy--it doesn't go out and in.
Displacement) A more sophisticated and processor-intensive way to add visual interest to an object, displacement actually changes the surface appearance of an object as it goes throuygh the rendering pipeline in image synthesis. IOW, the model you build does not take on displacement detail, but the rendering of the object does.
There are two kinds of displacements (as there are bumps) : An image controls the displacement or bump, or a procedure is called. A procedural texture is a "recipe" made out of math; you can see the results, but unlike an image file, a procedural texture can only be seen as the recipe is applied to a surface. Procedures can have fractals within them, and generally can be scaled smoothly, and are darned hard to write when you need something realistic. PIXAr totally subscribes to procedural shaders, and that's why PIXAR movies have this "less than real, dreamlike" quality. When you use an image to make displacements and bumps, the size of the bitmap is finite, and scaling the resulting surfaces sometimes yields artifacts (noise). But a surface that uses a bitmap for a decal, a reflection (sorry, reflection mapping can be done three ways: through a procedure, through ray tracing, or through an image)---is always as realistic looking as the image is.
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