Mipmaps are additional copies of a texture in a smaller resolution, each being one fourth of the resolution of the previous one (e.g. the first mipmap of a texture with a resolution of 2048x2048 has a resolution of 1024x1024 pixel). The game's engine will choose the texture with the resolution that covers the model best. Mipmaps have two purposes:
- The first being performance, as smaller variants of textures can be rendered.
- The second is improved anti-aliasing, as using textures without mipmaps causes pixelated edges in-game.
Comparison of a texture with and without mipmaps
This picture shows the difference between a texture with and without mipmaps. The skin has a large resolution (in this example, the texture has a resolution of 4048x4048 pixel) and covers the whole car, making the difference easy to spot. The skin on the left car has mipmaps, the one on the right car does not.
Up close however, the difference is barely noticeable:
Usage of mipmaps ingame
There are rare cases in which mipmaps decrease visual quality: For example, when textures and normal maps are used to create subtle surface structures or in other, similar cases, it might look better without mipmaps. Colorful emissive textures usually look better from a distance without mipmaps. Apart from that, mipmaps should be used whenever possible. OpenIV is able to automatically generate them, there's no additional effort needed.