Interactive Volume Illustration

In this paper we describe non-photorealistic rendering techniques for volumetric data sets. First, we outline an automatic approach that generates line drawings to illustrate such data sets and to augment traditional volume rendering techniques. For a number of seed points that are placed appropriately to represent selected volume structures curvature lines are traced and encoded by a sparse set of control points. These curves are finally drawn as hatching strokes modulated by anisotropic lighting and transparency. Second, in addition to line-art drawings we present efficient implementations of volume toon-shading and silhouette rendering using fragment shader hardware. All techniques together allow us to interactively illustrate volumetric data sets and to enhance important features using nonphotorealistic rendering techniques.