Kai Bürger Polina Kondratieva Jens Krüger Rüdiger Westermann Importance-Driven Particle Techniques for Flow Visualization. 71-78 2008 PacificVis http://dx.doi.org/10.1109/PACIFICVIS.2008.4475461 conf/apvis/2008 db/conf/apvis/pacificvis2008.html#BurgerKKW08