LOD

From Valve Developer Community

Level of Detail (LOD) is the principle of storing low-detail versions of an asset in memory and switching to them when the object is small/distant. This reduces the amount of processing required at the cost of increased memory size.

Care should be taken to ensure that the player does not notice the "pop" between LODs.

LOD in Source

• LOD Models / $lod
• MIP Mapping
• func_lod (fades out, not really LOD)