Polygon Budget

A polygon budget is a rule-of-thumb limit on the number of triangles allowed for any object or element based on the amount of space that object occupies. SimCity's polygon budget is measured based on lot size, not volume. Taller buildings are not allowed more polygons simply for being tall. Fortunately most tall buildings sit on larger lots and therefore have reasonable budgets compared to smaller buildings.

SimCity 2013 Polygon Budget

 * 0.5 triangles per square meter (for LOD0)

As an example all Shotgun Shacks sit on 16m x 32m lots: For LOD-3, the “Shotgun Shack” would need to be reduced to 32 triangles or less. 32 triangles isn’t much, but when a player sees LOD-3 of a building, it’s pretty far away.
 * 16m x 32m = 512m2
 * 512m2 x 0.5 triangles / m2 = 256 triangles
 * LOD-0 = 256 x 100% = 256 triangles
 * LOD-1 = 256 x 50% = 128 triangles
 * LOD-2 = 256 x 25% = 64 triangles
 * LOD-3 = 256 x 12.5% = 32 triangles

More Detailed Info on SimCity's Blog - How Things Work: Buildings