Environment Mapped Bump Mapping

The hubub

Matrox uses the bump mapping technique called "Environment Mapped Bump Mapping." This is the type of bump mapping that has been receiving all the attention lately because of all the G400 buzz. Originally called TriTech bump mapping, it's now known as Environment Mapped Bump mapping.

Environment Bump Mapping requires three different maps: the original texture, a bump map, and an environment map. From Matrox's site:

A bump map is essentially a differential value map derived from a height map…. The bump map contains a value for each texel coordinate of the conventional texture map. This value specifies a value from a different location within the environment map that should be applied to the texture map.

The bump map is combined with the environment map and the resulting "perturbed" environment map is applied to the original texture. In other words, for each texel coordinate of a texture map, there exists a corresponding environment map coordinate, the value of which is applied to the texel in order to create the lighting effect.

What's that again?

As with Dot 3, the bump map defines a depth or height for every pixel in the texture map, while the environment map takes care of any special effects. The bumps are calculated on a per-pixel basis. That means that the height and depth of every bump can vary over each polygon, resulting in a huge number of bumps for tons of detail. Environment Bump Mapping offers more lighting effects than embossing, because environment maps allow for extensive diffuse and specular lighting options.

One of the more impressive features of Environment Bump Mapping is its ability to simulate bump animation. With bump animation and environment map lighting, programmers can create scenes like moving waves on a shimmering lake.

Here are the Expendable screenshots that we're sure everyone has already seen, which demonstrates what is possible with environment mapped bump mapping.

Plain, flat textures

Animate Environment maps

Over at Matrox Users, we found an 2.78MB Expendable MPEG that shows the Environment Bump Mapping in action. Check it out.

That's all, folks!

That about does it for this installation of the FS 3D Guide! As always, questions and comments can be delivered to the FS Hardware Messageboard!