Shading

Shading, coloring, lighting, texturing.. loosely and generally speaking, they all indicate the same thing - how to add more interest to a scene.

Onscreen

Print

Flat shading: uses just a single normal [to make just one lighting calc.] for an entire polygon

Gouraud shading: a normal at each vertex

Phong shading: a normal at every pixel

Note that all of the above are capable of rendering ambient, diffuse as well as specular calculations.. It's just that the quality of the results 'differ' :)

In addition to the above, there is also 'fence shading' where a normal is calculated at a polygon's boundary (fence) pixels.

Ref - some more notes on specular highlights.

Diffuse lighting video clip

Specular highlights video clip There are three segments in this short clip (which I made on our dining table) featuring a pair of Utah Teapot models. First one shows object motion, second shows camera (eye) motion and the third, motion of the light sources. In all three cases, the highlights animate over the surfaces. This is because the location of a highlight is a function of surface (normal), camera and light source - changing one or more of the three will cause the highlight to shift.

Specular reflections

Shading networks

Slim

ShaderMan

ShadeTree