In
computer graphics
Computer graphics deals with generating images and art with the aid of computers. Computer graphics is a core technology in digital photography, film, video games, digital art, cell phone and computer displays, and many specialized applications. ...
, texture splatting is a method for combining different
textures. It works by applying an
alphamap (also called a "weightmap" or a "splat map") to the higher levels, thereby revealing the layers underneath where the alphamap is partially or completely transparent. The term was coined by Roger Crawfis and Nelson Max.
Optimizations
Since texture splatting is commonly used for
terrain rendering
Terrain cartography or relief mapping is the depiction of the shape of the surface of the Earth on a map, using one or more of several techniques that have been developed. Terrain or relief is an essential aspect of physical geography, and as su ...
in
computer game
A video game or computer game is an electronic game that involves interaction with a user interface or input device (such as a joystick, controller, keyboard, or motion sensing device) to generate visual feedback from a display device, mo ...
s, various optimizations are required. Because the underlying principle is for each texture to have its own
alpha channel
In computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate pass ...
, large amounts of
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembe ...
can easily be consumed. As a solution to this problem, multiple alpha maps can be combined into one texture using the red channel for one map, the blue for another, and so on. This effectively uses a single texture to supply alpha maps for four real-color textures. The alpha textures can also use a lower resolution than the color textures, and often the color textures can be tiled.
Terrains can also be split into chunks where each chunk can have its own textures. Say there is a certain texture on one part of the terrain that doesn’t appear anywhere else on it: it would be a waste of memory and processing time if the alpha map extended over the whole terrain if only 10% of it was actually required. If the terrain is split into chunks, then the alpha map can also be split up according to the chunks and so now instead of 90% of that specific map being wasted, only 20% may be.
Related techniques
Alpha-based texture splatting, though simple, gives rather unnatural transitions. Height-based texture blending attempts to improve on quality by blending based on a
heightmap
In computer graphics, a heightmap or heightfield is a raster image used mainly as Discrete Global Grid in secondary elevation modeling. Each pixel stores values, such as surface elevation data, for display in 3D computer graphics. A height ...
of each texture.
See also
*
Alpha compositing
In computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate pass ...
*
Blend modes
Blend modes (alternatively blending modes or mixing modes) in digital image editing and computer graphics are used to determine how two Layers (digital image editing), layers are blended with each other. The default blend mode in most applications ...
*
Splatting – a volume rendering technique
*
Texture mapping
Texture mapping is a term used in computer graphics to describe how 2D images are projected onto 3D models. The most common variant is the UV unwrap, which can be described as an inverse paper cutout, where the surfaces of a 3D model are cut ap ...
References
External links
Charles Bloom on Texture SplattingTexture Splattingin
Direct3D
Direct3D is a graphics application programming interface (API) for Microsoft Windows. Part of DirectX, Direct3D is used to render three-dimensional graphics in applications where performance is important, such as games. Direct3D uses hardware ...
* Crawfis, Roger and Nelson Max
Texture Splats for 3D Vector and Scalar Field Visualization Proceedings Visualization '93 (October 1993), IEEE CS Press, Los Alamitos, pp. 261–266.
Computer graphics
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