http://www.beyond3d.com/interviews/etqw/
Beyond3D:
Roughly a year ago today id and Splash Damage sent out a press release announcing the game and MegaTexture, a which was described simply as: "Battlefields are perfectly rendered using MegaTexture, a totally new rendering technology developed by id Software that crunches millions of polygons and a gigabyte-scale texture into a single, seamless and un-tiled landscape with unique detail down to the square inch or the un-obscured distant horizon." It has later surfaced that MT has the ability to handle a unique texture of 32,768 x 32,768 pixel size while only using around 8MB of video memory at all times. ETQW uses this for terrains only but John Carmack has stated, during the QuakeCon 2005 keynote, his intent to use this unique texturing capability on everything in the new engine id is currently working on.
Arnout Van Meer, developer, Splash Damage:
Enemy Territory: QUAKE Wars features a tool suite for creating MegaTextures called MegaGen. Once the Artist or Level Designer has completed the artwork, MegaGen outputs two entirely unique 4GB textures - a diffuse map containing colour data, and a normal map - and then combines them into a single 5GB data file. This data file is then split into unique tiles suitable for streaming, and then compressed to reduce disk space usage.
The resulting unique MegaTexture is around 500MB in size. This represents a reasonable tradeoff between ETQW├óÔé¼Ôäós visual quality and disk space usage (maintaining a shippable size for the game).