Also see a similar term, voxel .
backward mapping (inverse mapping or screen order)
Backward mapping (also known as inverse mapping...(WhatIs.com)
MMX Technology explained
Although not very easy to incorporate into the ...(ComputerWeekly.com)
In computer graphics, a texel (texture element) represents the smallest graphical element in two-dimensional (2-D) texture mapping to "wallpaper" the rendition of a three-dimensional ( 3-D ) object to create the impression of a textured surface. A texel is similar to a pixel (picture element) because it represents an elementary unit in a graphic. But there are differences between the texels in a texture map and the pixels in an image display. In special instances, there might be a one-to-one correspondence between texels and pixels in some parts of the rendition of a 3-D object. But for most, if not all, of a 3-D rendition, the texels and pixels cannot be paired off in such a simple way.
When a 3-D texture-mapped object appears close to the viewer so that the texture elements appear relatively large, there may be several pixels in each texel and the pattern of the texture map is easy to see. When the same 3-D object is removed to increasing distances, the texture-map pattern appears smaller and smaller. Eventually, each texel can become smaller than a pixel. Then an averaging process must be used; several texels are combined to form each pixel. If the object becomes distant enough, or if one of its facets appears at a sharp angle with respect to the viewer, the texels may become so small that the essence of the pattern is lost in the observed image.