ABSTRACT
A voxel is the three-dimensional extension of a pixel, and the word supposedly stems from volume pixel or volumetric pixel. Where images are two-dimensional arrays of pixels, voxel buffers are three-dimensional arrays of voxels. (See Figure 3.1.)
Just as with a two-dimensional image, we can access the contents of a voxel by its coordinate. The bottom-left corner of the buffer has coordinate (0 0 0) in the voxel coordinate space, and its neighbor in the positive direction along the x-axis is (1 0 0). When referring to the index along a given axis, it is common to label the variable i, j, and k for the x-, y-, and z-axes, respectively. In mathematic notation, this is often written using subscripts, such that a voxel buffer B has voxels located at Bi,j,k.
