Directional flow visualization of vector fields

The paper presents interactive flow visualization methods that highlight directional information in the flow field. An added benefit of the proposed methods is that they reduce the amount of data being displayed and hence reduce clutter. The main idea behind these methods is the use of light sources to select and highlight regions in the flow field with similar directions. Varying the lighting conditions, by moving the light source and/or adding more lights, emphasizes different vector directions, set of directions, and vectors within a specified angle of a particular direction. The methods are straight forward, computationally inexpensive, and can be combined with other techniques that use glyph representation and other flow geometry such as streamlines for feature visualization. The authors apply these methods to an analytic data set to help explain how they work, and then to a simulation data set to highlight flow reversals.