Incomputer graphics, atexel,texture element, ortexture pixel is the fundamental unit of atexture map.[1] Textures are represented byarrays of texels representing thetexture space, just as otherimages are represented by arrays ofpixels.
Texels can also be described byimage regions that are obtained through simple procedures such asthresholding.Voronoi tesselation can be used to define their spatial relationships—divisions are made at themidpoints between thecentroids of each texel and the centroids of every surrounding texel for the entire texture. This results in each texel centroid having aVoronoi polygon surrounding it, which consists of all points that are closer to its own texel centroid than any other centroid.[2]
When texturing a 3D surface or surfaces (a process known astexture mapping), therenderer maps texels to appropriate pixels in the geometric fragment (typically a triangle) in the output picture. On modern computers, this operation is accomplished on thegraphics processing unit.
The texturing process starts with a location in space. The location can be in world space, but typically it is local to a model space so that the texture moves with the model. A projector function is applied to the location to change the location from a three-element vector () to a two-element () vector with values ranging from zero to one (uv).[3] These values are multiplied by the resolution of the texture to obtain the location of the texel. When a texel is requested that is not on aninteger position,texture filtering is applied.
When a texel is requested that is outside of the texture, one of two techniques is used: clamping or wrapping.Clamping limits the texel to the texture size, moving it to the nearest edge if it is more than the texture size.Wrapping moves the texel in increments of the texture's size to bring it back into the texture. Wrapping causes a texture to be repeated; clamping causes it to be in one spot only.