@misc{WiebelVosHege, author = {Wiebel, Alexander and Vos, Frans M. and Hege, Hans-Christian}, title = {Perception-Oriented Picking of Structures in Direct Volumetric Renderings}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-14343}, number = {11-45}, abstract = {Radiologists from all application areas are trained to read slice-based visualizations of 3D medical image data. Despite the numerous examples of sophisticated three-dimensional renderings, especially all variants of direct volume rendering, such methods are often considered not very useful by radiologists who prefer slice-based visualization. Just recently there have been attempts to bridge this gap between 2D and 3D renderings. These attempts include specialized techniques for volume picking that result in repositioning slices. In this paper, we present a new volume picking technique that, in contrast to previous work, does not require pre-segmented data or metadata. The positions picked by our method are solely based on the data itself, the transfer function and, most importantly, on the way the volumetric rendering is perceived by viewers. To demonstrate the usefulness of the proposed method we apply it for automatically repositioning slices in an abdominal MRI scan, a data set from a flow simulation and a number of other volumetric scalar fields. Furthermore we discuss how the method can be implemented in combination with various different volumetric rendering techniques.}, language = {en} } @misc{ClasenPaarProhaska, author = {Clasen, Malte and Paar, Philip and Prohaska, Steffen}, title = {Level of Detail for Trees Using Clustered Ellipsoids}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-14251}, number = {11-41}, abstract = {We present a level of detail method for trees based on ellipsoids and lines. We leverage the Expectation Maximization algorithm with a Gaussian Mixture Model to create a hierarchy of high-quality leaf clusterings, while the branches are simplified using agglomerative bottom-up clustering to preserve the connectivity. The simplification runs in a preprocessing step and requires no human interaction. For a fly by over and through a scene of 10k trees, our method renders on average at 40 ms/frame, up to 6 times faster than billboard clouds with comparable artifacts.}, language = {en} }