Chapter 5 Classification of Volume Rendering Algorithms

The object of this chapter is to give the general background of volume graphics together with a general classification. It is important to mention that there is not a complete agreement on a standard volume visualization vocabulary yet, a nomenclature is approaching consensus, where multiple terms exist for the same concept. And even a standard classification of volume visualization algorithms is not available. The classification of the algorithms given below is therefore not binding. All of the names of the algorithms are carefully taken into consideration and emphasized.

Volume visualization has been the most active sub-area of researches during last 20 years in scientific visualization. To be useful, volume visualization techniques must offer understandable data representations, quick data manipulation, and reasonably fast rendering. Scientific users should be able to change parameters and see the resultant image instantly. Few present day systems are capable of this type of performance; therefore researchers are still studying many new ways to use volume visualization effectively.

The rendering approaches differ in several aspects which can be used for their detailed classification in various ways [8, 9, 17-21]. Coarsely, volume visualization is done using two different approaches based on the portion of the volume raster set which they render; (Figure 1.4, Figure 1.5)

1.Surface rendering (or indirect volume rendering),

2.Volume rendering (or direct volume rendering).