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Colloquy Cycle WS 2003/04
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| Current Schedule
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In the winter term of 2003/04 the following talks will be organized by our Institute. The talks are partially financed by the "Arbeitskreis Graphische Datenverarbeitung" of the OCG (Austrian Computer Society)
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| Date | Speaker | Title | Time | Location |
| 22.09.2003 |
Alessandro Rizzi (Università di
Milano Italy); Alessandro Artusi (ICGA); Caro Gatta (Università di
Milano Italy) |
Speed-up techniques for a perceptually based Tone Mapping Operator
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15.00-16.00 s.t. | Seminarraum 186, Favoritenstraße 9, 5. Stock |
| 10.10.2003 |
Dirk Bartz (Universität Tübingen, Germany) |
Virtual Medicine, Medical Imaging, and Large Data Visualization
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10.00-11.00 s.t. | Seminarraum 186, Favoritenstraße 9, 5. Stock |
| 17.10.2003 |
Pascal Lienhardt (Universität Poitiers, France) |
Combinatorial Maps and other Topological Structures for Geometric Modeling
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11.00-12.00 s.t. | Seminarraum 186, Favoritenstraße 9, 5. Stock |
| 28.11.2003 |
László Neumann (Universitat de Girona, Spain) |
Color Appearance and Design in Interiors using Multispectral Global Illumination Models
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10.00-11.00 s.t. | Seminarraum 186, Favoritenstraße 9, 5. Stock |
| Speed-up techniques for a perceptually based Tone Mapping Operator
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Alessandro Rizzi, Italy; Alessandro Artusi, Austria; Caro Gatta, Italy
The status of the current output devices as: display and printers, limit to visualize or print correctly High Dynamic Range images.
Tone mapping helps to resolve this problem, but when accurate visualization is requested local operators are required. Local
operators are able to capture this goal, but they require high computational costs that reduce their use in real
applications. In this talk we propose a speed-up technique in order to reduce the computational costs of an existing local operator
derived by retinex. It consists to extract both: global and local information from the existing operator and to extrapolate
it on the whole image. We show how to extract the global information sampling the input image and using singular
value decomposition (SVD). On the other hand, the local information is extracted selecting a small number of samples for each
pixel of the input image and applying directly the local operator. We show the efficiency of our method on several images, and the
time performances comparing it with the original local operator.
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| Virtual Medicine, Medical Imaging, and Large Data Visualization
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Dirk Bartz, Germany
Medical imaging is one of the most established practical fields of visualization.
While most used methods deal with individual images
from 3D scanners - volumes are seen as stack of images -, 3D
visualizations are slowly moving into the daily practice of research
hospitals.
Major challenges in this process is the difficult specification of how
the features in volume datasets are visualized (transfer functions,
etc), occlusion of interesting features by others, and fast increasing
size of datasets. While a few years ago 256^3 datasets were the
standard size in radiology, the current standard size already
increased to 512^2x1000 volumes. Soon, highfield-MRI scanners will
even produce volumes of 2048^2 x 1000 in research applications.
In this talk, I will discuss several techniques how to deal with
large medical data. In particular, I will present work in the
context of virtual endoscopy, a medical procedure oriented
visualization technique that provides an environment familiar
to physicians.
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| Color Appearance and Design in Interiors using Multispectral Global Illumination Models
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László Neumann, Spain
In closed environment, especially in bright colored interiors, there occurs a
significant change of saturation and some shifting of hue of original selected
colors. This is due to multiple light interreflections. The human vision
mechanism partly reduces this effect thanks to the change of the reference
white. We can use multispectral radiosity or other multispectral global
illumination models to compute the physical effects. A color appearance model, the new and powerful CIECAM02 model, will be used to compute the perceptual aspects.
The CIECAM02 includes the luminance and chromatic adaptation effects, and
it has compact forward and inverse transformation formulas. The input data
for the color appearance model is ensured by computing the multispectral
radiosity solution. Thereby both the spectral radiance for every viewpoint
and view direction and the spectral irradiance on every path of the scene are known.
Nearly all earlier global illumination approaches ignored the often strong changes
of originally selected colors. Using the presented method the selection or mixture
of paints is possible with the same, after physical and perceptual effects, color
appearance previously selected under standard viewing condition in a color atlas.
Finally some questions of perceptual metamerism to ensure highly constant color
appearance under different viewing conditions and some aesthetical rules of color
design will be discussed.
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