Lightmaps are composed of lumels (Lumination elements), analogous to texels in Texture Mapping. Smaller lumels yield a higher resolution lightmap, providing finer lighting detail at the price of reduced performance and increased memory usage. For example, a lightmap scale of 4 lumels per world unit would give a lower quality than a scale of 16 lumels per world unit. Thus, in using the technique, level designers and 3d artists often have to make a compromise between performance and quality; if high resolution lightmaps are used too frequently then the application may consume excessive system resources, negatively affecting performance. Lightmap resolution and scaling may also be limited by the amount of disk storage space, bandwidth/download time, or texture memory available to the application. Some implementations attempt to pack multiple lightmaps together in a process known as "atlasing" to help circumvent these limitations.