In real-time polygon rendering (part of computer graphics), lightmaps are used as a means of faking the effects of vertex lighting by using a texture map. Since lighting calculations (especially in software without hardware acceleration) are very slow in situations, it often makes sense to precompute the effect of lighting on the polygon itself. Of course, this only works if the lights in the scene are static. The lightmaps would be then used as a texture map (usually as an additional, partially transparent texture on top of the material texture).

This technique was used in older games quite frequently. It has largely disappeared as a result of hardware acceleration of polygon rendering engines.