Visualization is defined in the Oxford English Dictionary as "the action or fact of visualizing, the power or process of forming a mental picture or vision of something not actually present to the sight." As the old adage "a picture is worth a thousand words" goes, visualization can be defined as a method that makes the best use of a person's perceptual abilities to observe, access, and understand data and information. Generally speaking, the purpose of visualization is to provide the user with not only a visual presentation and interpretation of the data and information but also a better understanding of the phenomenon behind the data and information. A more recent and domain-specific definition of visualization is given by the following: "Visualization provides an interface between two powerful information processing systems—human mind and the modern computer. Visualization is the process of transforming data...