Visualizing vector fields is a difficult problem. Whereas scalar
fields have a scalar value at each sample point, vector fields
have an *n*-component vector (usually 2 or 3 components) at each point.
Vector fields occur in applications such as computational fluid
dynamics and typically represent the flow of a gas or liquid.
Visualization of the field provides a way to better observe and
understand the flow patterns.

Vector field visualization techniques can be grouped into 3 general classes: