Classification of visualization techniques is often based on
the dimension of the domain of the quantity that is visualized,
i.e. the number of independent variables of the domain on which
the quantity acts, and on the type of the quantity, i.e. scalar,
vector, or tensor .
In MHD, two scalar quantities occur, viz. temperature (or pressure) and density, and two vector quantities viz. magnetic field and velocity field. These quantities are defined on a four-dimensional domain which is spanned up by the space and time coordinates. The time dependence is treated different than other dependencies. In particular, animation is used to visualize this dependency (see below).
Visualization techniques can also be divided into surface rendering techniques, and (direct) volume rendering techniques . Surface rendering is an indirect geometry based technique which is used to visualize structures in 3D scalar or vector fields by converting these structures into surface representations first and then using conventional computer graphics techniques to render these surfaces. Direct volume rendering is a technique for the visualization of 3D scalar data sets without a conversion to surface representations.