| Fast Visualization of Object Contours by Non-Photorealistic Volume Rendering |
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In this paper we present a fast visualization technique for volumetric data, which is based on a recent non-photorealistic rendering technique. Our new approach enables alternative insights into 3D data-sets (compared to traditional approaches such as direct volume rendering or iso-surface rendering). Object contours, which usually are characterized by locally high gradient values, are visualized regardless of their density values. Cumbersome tuning of transfer functions, as usually needed for setting up DVR views, for example, is avoided. Instead, a small number of parameters is available to adjust the non-photorealistic display. Based on the magnitude of local gradient information as well as on the angle between viewing direction and gradient vector, data-values are mapped to visual properties (color, opacity), which then are combined to form the rendered image (MIP is proposed as the default compositing stragtegy here). Due to the fast implementation of this alternative rendering approach, it is possible to interactively investigate the 3D data, and quickly learn about internal structures. Several further extensions of our new approach, such as level lines are also presented in this paper.
This project is a joint research activity between 1.) the visualization research at the Institute of Computer Graphics and Algorithms at Vienna University of Technology, Austria, and 2.) the basic research on visualization at VRVis, Vienna, Austria. Parts of this work have been done as part of the VisMed project, which is funded by the Austrian ``Forschungsförderungsfond für die gewerbliche Wirtschaft'', whereas other parts of this work have been carried out as parts of the basic research project ``interactive visualization'' at the VRVis research center, which is funded by an Austrian governmental research projects called Kplus. The CT scans of the human head and the engine block are part of the Chapel Hill Volume Rendering Test Dataset. The CT scan of the human vertebrae is courtesy of Tiani Medgraph.
A paper with title ``Fast Visualization of Object Contours by Non-Photorealistic Volume Rendering'' (authored by Csébfalvi Balázs [1], Lukas Mroz [2], Helwig Hauser [2], Andreas König [1], and M. Eduard Gröller [1]) is available as a technical report from VRVis. Another web page about this work is available from the Institute of Computer Graphics and Algorithms at Vienna University of Technology, Austria.
left: non-photorealistic rendering of a human torso, exhibiting the structure of inner organs.
right: non-photorealistic rendering of screws within a human spine.
(to retrieve an enlarged version of the images, click on them):
Below: non-photorealistic rendering of an engine block.
Below: non-photorealistic rendering of human vertebrae with screws inside.
Below: non-photorealistic visualization of internal organs.
Below (a-f): interactive non-photorealistic rendering results.
In case of questions, comments, etc., please mailto:Hauser@VRVis.at.