“Anisotropy” in 3D rendering means that a surface reflects differently from different angles. For example, some metals have a distinct small grain or “brushed” surface.
The Anisotropy channel adds the ability to get subtle, realistic anisotropic effects such as brushed metal surfaces.
To use this feature, use the Anisotropy channel slider and image map field. Then decide whether to enable the new Anisotropy checkboxes in the other channels, depending on the needs of your project. You can use UV mapping to control the strand direction in anisotropic textures.
For more information see Chapter 9 - Using Image Textures in the User Guide, the new tutorials on the Strata3DUniversity.com, and the StrataCafe.com Design 3D CX forum.