MegaTexture
Encyclopedia
MegaTexture refers to a texture allocation technique facilitating the use of a single extremely large texture
rather than repeating multiple smaller textures. It is featured in Splash Damage
's game Enemy Territory: Quake Wars
and was developed by id Software
technical director John Carmack.
MegaTexture employs a single large texture space for static terrain. The texture is stored on removable media
or a computer's hard drive and streamed as needed, allowing large amounts of detail and variation over a large area with comparatively little RAM usage. Depending on the pixel resolution per square meter, covering a large area could require several gigabytes of memory. However, an average PC has only 2 or 3 gigabytes of RAM available, also filled by the rest of the game and the underlying operating system, limiting the amount available for texturing. As the player moves around the game, different sections of the megatexture are loaded into memory. They are then scaled to the correct size and applied to the 3D models of the terrain.
MegaTexture is an implementation of the idea of clipmapping
.
, powered by the id Tech 5
engine, uses a more advanced technique called Virtual Texturing. Textures can measure up to 128000×128000 pixels and are also used for in-game models and sprites, etc. and not just the terrain. The upcoming game Doom 4
will also use these.
(SVO). Potentially id Tech 6
could utilize this technique. It works by raycasting the geometry represented by voxels (instead of triangles) stored in an octree
. The goal being to be able to stream parts of the octree into video memory, going further down along the tree for nearby objects to give them more details, and to use higher level, larger voxels for further objects, which give an automatic level of detail (LOD) system for both geometry and textures at the same time. The geometric detail that can be obtained using this method is nearly infinite, which removes the need for faking 3-dimensional details with techniques such as normal mapping
. Despite that most Voxel rendering tests use very large amounts of memory (up to several Gb), Jon Olick of id Software
claimed it's able to compress such SVO to 1.15 bits per voxel of position data.
Texture mapping
Texture mapping is a method for adding detail, surface texture , or color to a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Dr Edwin Catmull in his Ph.D. thesis of 1974.-Texture mapping:...
rather than repeating multiple smaller textures. It is featured in Splash Damage
Splash Damage
Splash Damage is an independently-owned British game development company that specializes in multiplayer first-person shooter games. The studio is best known as the creator of the Enemy Territory franchise for id Software.-History:...
's game Enemy Territory: Quake Wars
Enemy Territory: Quake Wars
Enemy Territory: Quake Wars is a first-person shooter video game, and is the follow-up to the 2005 title Quake 4. It is also the first game in the series to be rated T by the ESRB...
and was developed by id Software
Id Software
Id Software is an American video game development company with its headquarters in Richardson, Texas. The company was founded in 1991 by four members of the computer company Softdisk: programmers John Carmack and John Romero, game designer Tom Hall, and artist Adrian Carmack...
technical director John Carmack.
MegaTexture employs a single large texture space for static terrain. The texture is stored on removable media
Removable media
In computer storage, removable media refers to storage media which is designed to be removed from the computer without powering the computer off.Some types of removable media are designed to be read by removable readers and drives...
or a computer's hard drive and streamed as needed, allowing large amounts of detail and variation over a large area with comparatively little RAM usage. Depending on the pixel resolution per square meter, covering a large area could require several gigabytes of memory. However, an average PC has only 2 or 3 gigabytes of RAM available, also filled by the rest of the game and the underlying operating system, limiting the amount available for texturing. As the player moves around the game, different sections of the megatexture are loaded into memory. They are then scaled to the correct size and applied to the 3D models of the terrain.
MegaTexture is an implementation of the idea of clipmapping
Clipmap
Clipmapping is a method of clipping a mipmap to a subset of data pertinent to the geometry being displayed. This is useful for loading as little data as possible when memory is limited, such as on a graphics processing unit.- External links :* * *...
.
Virtual texturing
RageRage (video game)
Rage is a first-person shooter video game by id Software which was released on October 4, 2011 in North America. It uses the company's new OpenGL based id Tech 5 engine. The game was first shown as a tech demo on June 11, 2007, at Apple's WWDC, and was officially announced on August 2, 2007, at...
, powered by the id Tech 5
Id Tech 5
id Tech 5 is the latest proprietary game engine being developed by id Software, currently still being actively upgraded, and follows its predecessors, id Tech 1, 2, 3 and 4. It is a major advancement over id Tech 4. The engine was first demonstrated at the WWDC 2007 by John D...
engine, uses a more advanced technique called Virtual Texturing. Textures can measure up to 128000×128000 pixels and are also used for in-game models and sprites, etc. and not just the terrain. The upcoming game Doom 4
Doom 4
Doom 4 is the upcoming multi-platform installment of the Doom series by id Software. The game will use the company's new id Tech 5 engine and is slated for simultaneous release on Microsoft Windows, PlayStation 3 and Xbox 360...
will also use these.
Future technology evolution
Id has presented a more advanced technique that builds upon the MegaTexture idea and virtualizes both the geometry and the textures to obtain unique geometry down to the equivalent of the texel: the Sparse Voxel OctreeSparse voxel octree
A sparse voxel octree is a 3D computer graphics rendering technique using a raycasting or sometimes a ray tracing approach into an octree data representation....
(SVO). Potentially id Tech 6
Id Tech 6
id Tech 6 is an upcoming OpenGL based game engine under preliminary development by id Software, which will tentatively follow id Tech 5 for id Software games following Rage, and Doom 4....
could utilize this technique. It works by raycasting the geometry represented by voxels (instead of triangles) stored in an octree
Octree
An octree is a tree data structure in which each internal node has exactly eight children. Octrees are most often used to partition a three dimensional space by recursively subdividing it into eight octants. Octrees are the three-dimensional analog of quadtrees. The name is formed from oct + tree,...
. The goal being to be able to stream parts of the octree into video memory, going further down along the tree for nearby objects to give them more details, and to use higher level, larger voxels for further objects, which give an automatic level of detail (LOD) system for both geometry and textures at the same time. The geometric detail that can be obtained using this method is nearly infinite, which removes the need for faking 3-dimensional details with techniques such as normal mapping
Normal mapping
In 3D computer graphics, normal mapping, or "Dot3 bump mapping", is a technique used for faking the lighting of bumps and dents. It is used to add details without using more polygons. A common use of this technique is to greatly enhance the appearance and details of a low polygon model by...
. Despite that most Voxel rendering tests use very large amounts of memory (up to several Gb), Jon Olick of id Software
Id Software
Id Software is an American video game development company with its headquarters in Richardson, Texas. The company was founded in 1991 by four members of the computer company Softdisk: programmers John Carmack and John Romero, game designer Tom Hall, and artist Adrian Carmack...
claimed it's able to compress such SVO to 1.15 bits per voxel of position data.
See also
- Surface cachingSurface cachingSurface caching is a computer graphics technique pioneered by John Carmack, first used in the computer game Quake to apply lightmaps to level geometry. Carmack's technique was to combine lighting information with surface textures in texture-space when primitives became visible , exploiting...
- Texture mappingTexture mappingTexture mapping is a method for adding detail, surface texture , or color to a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Dr Edwin Catmull in his Ph.D. thesis of 1974.-Texture mapping:...
- id SoftwareId SoftwareId Software is an American video game development company with its headquarters in Richardson, Texas. The company was founded in 1991 by four members of the computer company Softdisk: programmers John Carmack and John Romero, game designer Tom Hall, and artist Adrian Carmack...
- Doom 3Doom 3Doom 3 is a science fiction horror video game developed by id Software and published by Activision. An example of the first-person shooter genre, Doom 3 was first released for Microsoft Windows on August 3, 2004. The game was later adapted for Linux, as well as being ported by Aspyr Media for Mac...
- Enemy Territory: Quake WarsEnemy Territory: Quake WarsEnemy Territory: Quake Wars is a first-person shooter video game, and is the follow-up to the 2005 title Quake 4. It is also the first game in the series to be rated T by the ESRB...
- Doom 4Doom 4Doom 4 is the upcoming multi-platform installment of the Doom series by id Software. The game will use the company's new id Tech 5 engine and is slated for simultaneous release on Microsoft Windows, PlayStation 3 and Xbox 360...
- ClipmapClipmapClipmapping is a method of clipping a mipmap to a subset of data pertinent to the geometry being displayed. This is useful for loading as little data as possible when memory is limited, such as on a graphics processing unit.- External links :* * *...
External links
- id Software
- Splash Damage
- John Carmack on MegaTexture
- Arnout van Meer on Quake Wars
- Sparse Virtual Textures by Sean Barrett, a related technique with more technical explanations (video demonstration).