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B. Csebfalvi, St. Bruckner, E. Gröller et al.:
"Illumination-Driven Opacity Modulation for Expressive Volume Rendering";
Vortrag: Workshop on Vision, Modeling, and Visualization Conference (VMV 2012), Magdeburg, Germany; 12.11.2012 - 14.11.2012; in: "Workshop on Vision, Modeling, and Visualization Conference 2012 (VMV 2012)", Proceedings of Vision, Modeling & Visualization 2012, (2012), S. 103 - 109.

Using classical volume visualization, typically a couple of isosurface layers are rendered semi-transparently to show the internal structures contained in the data. However, the opacity transfer function is often difficult to specify such that all the isosurfaces are of high contrast and sufficiently perceivable. In this paper, we propose a volumerendering technique which ensures that the different layers contribute to fairly different regions of the image space. Since the overlapping between the effected regions is reduced, an outer translucent isosurface does not decrease significantly the contrast of a partially hidden inner isosurface. Therefore, the layers of the data become visually well separated. Traditional transfer functions assign color and opacity values to the voxels depending on the density and the gradient. In contrast, we assign also different illumination directions to different materials, and modulate the opacities view-dependently based on the surface normals and the directions of the light sources, which are fixed to the viewing angle. We will demonstrate that this model allows an expressive visualization of volumetric data.

volume rendering, illumination, illustrative visualization

http://dx.doi.org/10.2312/PE/VMV/VMV12/103-109

http://publik.tuwien.ac.at/files/PubDat_214385.pdf