Pyramiding

Pyramids or overviews create lower resolution views of an original dataset. Often several pyramids are created at various lower resolutions to be used in the place of the original raster when only a snapshot or overview of the data is required. An example of when a pyramid is typically employed, is when a raster viewer zooms out leaving a smaller raster with less detail. Often the smaller raster is rendered using a cached pyramid instead of resampling the image to a lower resolution at the time of the zoom out request.