mipmapping

Mipmapping is a texture-mapping technique used in 3D computer graphics to improve image quality and rendering efficiency when textures are viewed at smaller sizes or at oblique viewing angles. It stores multiple prefiltered versions of a texture, forming a mipmap pyramid. Each level is a downsampled copy of the previous one, typically half the width and height, so the total memory for all levels is about 4/3 of the base texture.

During rendering, the graphics pipeline selects an appropriate mipmap level based on the projected size of the texture on screen, often referred to as the texel footprint. The sampling can interpolate between neighboring texels in the chosen level, or between levels in a process called trilinear filtering to reduce visible transitions. Within each level, standard filtering such as bilinear or bicubic may be used. This approach reduces aliasing, improves texture cache coherence, and lowers texture bandwidth.

Mipmaps are usually generated automatically by the graphics API or hardware when textures are created or updated. They can be produced by simple downsampling filters or more sophisticated prefiltered methods. While they add memory overhead, the overall cost is predictable and widely considered worthwhile for real-time rendering.

Limitations include potential blurring of fine detail and shimmering artifacts during motion as the engine swaps between levels. Anisotropic filtering is often used in conjunction with mipmapping to preserve detail for textured surfaces viewed at steep angles. Mipmapping remains a standard technique in modern rendering pipelines for efficient and higher-quality texture sampling.