of applied smoothing.

**Depth anchoring.** To enable VSS to become a canvas for communicating depth of the visualized vessel trees, it is crucial that the vessel tree is visually associated with the VSS. Only through such an association, to which we refer as depth anchoring, the depth as communicated through the VSS is intuitively transferred to the vessel structure. To realize depth anchoring in the context of our design guidelines, we have decided to exploit natural illumination effects. Furthermore, to be able to perform depth anchoring at interactive frame rates, we use a screen space ambient occlusion technique [@ritschel2009approximating]. Figure \[fig:anchoring\] shows the effect of depth anchoring by visualizing a VSS without (a) and with depth anchoring (b) achieved through ambient occlusion. It can be clearly seen that the vessel structures seem to be aligned along the VSS when enabling depth anchoring. This in turn results in an intuitive transfer of depth information between the VSS and the vessel structure.

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To establishes a clear visual connection between the VSS and the vascular surface model, shading of the VSS plays also a major role. If the vessel geometry and the VSS are illuminated with the same lighting settings, the 