Mesh subdivision

Mesh Subdivision is a technique used to add detail to a polygon mesh by breaking into smaller pieces the polygons in the mesh. Mesh subdivision techniques are often used in 3D computer games, and in other programs such as Google Earth (tm). Because computers are limited in the number of polygons they can render per second, different techniques are often used to reduce the number of polygons visible at any given time, while still keeping the image as detailed looking as possible.

The polygons (usually triangles) in the mesh are divided in a way that the ones closest to the viewpoint are much smaller, and the size of the polygons grows the farther they are from the viewpoint. This is a Level Of Detail (LOD) technique. The mesh starts with a few very large polygons which are divided into smaller and smaller ones as the viewpoint gets closer to them. Polygons will also be recombined when the viewpoint gets farther away, or the polygons are no longer visible (see for example View frustum culling). When a polygon is divided altitude and other attributes will be loaded and assigned to the new vertices.