Add to ORKGNon-photorealistic (NPR) techniques are usually applied to produce stylistic renderings. However, they can also be useful to visualize scientific datasets. NPR techniques are often able to simplify data, pro-ducing clearer images than traditional photorealistic methods. We propose a framework for visualizing volume datasets using non-photorealistic techniques. Our framework is based on particle systems, with user-selectable rules affecting properties of the parti-cles such as position and appearance. The techniques presented do not require the generation of explicit in-termediary surfaces. Furthermore, the framework is versatile enough to produce a variety of illustrative techniques within the same framework.