Illustrative Rendering of Vortex Cores

Vortices are features crucial for understanding transitional and turbulent flow fields, and have often been visualized using isosurfaces, hulls, and line-like structures. However, they have not been represented in a nonphotorealistic manner that intuitively reflects their local characteristics. We introduce a novel visualization method that represents these features as illustrative vortex cores, and show how this illustrative method clearly depicts vortex properties such as direction, rotational strength, spatial extension, and underlying flow behavior simultaneously, in a fashion superior to standard visualization approaches. Our non-photorealistic visualizations leverage the axis and rotational properties of a vortex detector to depict the direction and the rotational strength of vortices, respectively. Furthermore, we extract flow behavior in the vicinity of the vortex cores to provide context for the vortices that we extract. We demonstrate the efficacy of our illustrative vortex extraction framework in two commonly used data sets by showing how they characterize the properties of the examined flow fields.