A Library of Attribute Set Table Groups.
For efficiency, the source of this transmittal uses a library of terrain textures, which are repeated at intervals across the terrain. Consequently, a limited number of Image Mapping Function, Color pairs are repeated across a large number of Polygons as components.
Rather than creating many duplicate objects, the data provider creates an Attribute Set Table Library. Each of the Image Mapping Function, Color pairs is placed in an Attribute Set, which is in turn stored in the primary Attribute Set Table of an Attribute Set Table Group within the library.
Each Polygon is then given an Attribute Set Index component, which is associated to the appropriate Attribute Set Table Group.