Volume rendering is a powerful computer graphics technique for the visualization of large quantities of volume data. It consists of trying to model the transparent nature of the data, not only its surface. In more specific terms, volume rendering is the generation of images from discrete samples of volume data that do not directly attempt to resample the position of the objects (as opposed to surface tracking methods [31]).
There are several algorithms developed for volume rendering [35,1]. A brief explanation of some of these methods is given below, for the purpose of enlighting the reader in the basic vocabulary and algorithms of the field. For a good introduction to computer graphics, see [27,28].