Directional Flow Visualization of 2D and 3D Vector Fields

No single natural representation exists for visualizing all of the information in a vector eld. As a result, numerous methods have been developed, each emphasizing diierent aspects of the ow. This paper presents a method of ow visualization that highlights directional information in the eld by overloading feature glyphs with directional information information through a technique similar to bump mapping 1]. At each sampled point in the 3D volume a glyph is associated with the vector at that point. Vector magnitude is mapped to glyph hue and the glyph surface normals are perturbed proportional to vector direction. Glyph surface shading based on variable lighting conditions and the perturbed surface normals then reveal directional information in the eld. Varying the lighting conditions emphasizes diierent vector directions and direction ranges. Alternatively, the glyph intensity can be mapped to vector magnitude and lighting calculations eeect glyph hue rather than intensity. The method is straight forward, computationally inexpensive, and can be combined with other techniques that use glyph representation for feature visualization.