be visualized, it is essential to visualize these functional parameters in the context of the morphology, as only then the association between function and structure becomes possible. Consequently, most existing visualization techniques convey the functional parameters as being overlaid over the vessel. While this naturally interferes with the communication of surface details through shading, research related to color constancy suggests, that this proceedings still maintains a reasonable perception of the individual objects [@foster2011color]. Nevertheless, the mapping of functional parameters exploits the same color channel as already used to communicate the vessel’s surface structure. Therefore, it can not efficiently be exploited to communicate additional depth cues.

**Instrumentation avoidance.** Vessel visualization should ideally not rely on an instrumentation of the viewer, i.e., they should be effective without wearing glasses or using other aids. While stereoscopic rendering techniques could be considered as being very effective in communicating depth, they require an instrumentation of the user via stereo glasses and are thus less desirable for medical visualizations. Furthermore, along a similar line, ideally a vessel visualization technique also works on static images. This is important, since often images are parts of medical reports, which are still today often printed and exchanged on paper.

**Intuitive 