if you google LIC you’ll find a heap of papers about this relatively old technique of visualising vector fields. its handy as it shows you a true representation of forces (direction & magnitude) within a field.

ive stumbled onto this technique when researching streamlines. by definition, a line that is instantaneously tangent to the velocity vector of the vector flow.

this is what it looks like when you scatter a bunch of streamlines around a vector field.

the code came from this implementation and ive ported it over into OF.

http://www.cs.utah.edu/~wmartin/cs523project/

[attachment=0:15mhem7z]110314_lic.zip[/attachment:15mhem7z]