Current Schedule

In the summer term of 2002 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)

Date SpeakerTitleTimeLocation
12.4.2002 Joseph Newman (AT&T Cambrige Research, UK) Living in an Augmented Sentient Environment 10.00-11.00 s.t.Seminarraum 186, Favoritenstraße 9, 5. Stock
3.5.2002 Ralph Schönfelder (DaimlerChrysler Virtual Reality Competence Center, Ulm, Germany) VRCC und der Virtual Reality Interaktions-Baukasten 10.00-10.45 s.t.Seminarraum 186, Favoritenstraße 9, 5. Stock
12.6.2002 Oleg Veryovka (New Media Innovation Centre, Vancouver, Canada) Making Video Games 9.00-9.45 s.t.Seminarraum 186, Favoritenstraße 9, 5. Stock
14.6.2002 Francois Faure (iMAGIS-GRAVIR/IMAG, Montbonnot, France) Interactive vegetal scenes 10.00-10.45 s.t.Seminarraum 186, Favoritenstraße 9, 5. Stock
17.6.2002 Markus Gross (Computer Graphics Laboratory, ETH Zürich, Switzerland) Facial Surgery Planning and Simulation 17:00 s.t.Zemanek Hörsaal, 1040 Wien, Favoritenstr. 11/Erdgeschoß/roter Bereich
21.6.2002 Markus Gross (Computer Graphics Laboratory, ETH Zürich, Switzerland) The blue-c Project: virtual collaboration 10:00-11:00 s.t.Seminarraum 186, Favoritenstraße 9, 5. Stock
21.6.2002 Alessandro Rizzi (University of Milano, Dipartimento di Tecnologia dell'Informazione, Italy) Color in context: from perception to image enhancement 11:00-12:00 s.t.Seminarraum 186, Favoritenstraße 9, 5. Stock

Previous Schedules


Living in an Augmented Sentient Environment

Joseph Newman, AT&T Cambrige Research

At AT&T Laboratories Cambridge, we have built a system that uses sensors to update a model of the real world. The state of the environment is encapsulated within the model in the form of data objects which correspond to real world objects. By using data within the model we can create applications that respond in an appropriate way to changes in the environment. To the users of the system, it therefore appears that the system shares the users' perceptions of the world, and so we refer to it as a sentient system. An accurate model of the environment requires detailed knowledge of the 3D positions and orientations of objects in the environment. As part of the sentient system we have developed a scalable, in-building tracking system that can provide location information for both of these purposes.

Augmented Reality (AR) both exposes and supplements the user's view of the real world. We have implemented two different AR systems; the first uses a head-mounted display connected to a laptop, whilst the second uses a PDA to provide a convenient portal with which the user can quickly view the augmented world. The scale and scope of the deployment of the sentient system throughout all three floors of our building has allowed us to continuously provide a rich AR experience.

Interactive vegetal scenes

Francois Faure, iMAGIS-GRAVIR/IMAG, Montbonnot, France

There is a growing interest of the videogame industry for interactive vegetal scenes. However, vegetal scenes exhibit a high geometrical and physical complexity. We present new aproaches to visualize and animate forests and prairies at interactive rates.

Facial Surgery Planning and Simulation

Markus Gross, Computer Graphics Laboratory, ETH Zürich, Switzerland

This talk will give a survey of our research in facial surgery simulation with an emphasis on graphics and physically-based modelling. I will contrast conventional procedures for surgical planning to our approach, which foresees a fully three-dimensional, realistic prediction of the surgical outcome. To this end we will accompany a patient through the entire process of planning, medical treatment and simulation. In various preprocessing steps a 3D physically-based facial model is reconstructed from CT data and laser range scans. The reconstruction process includes skull extraction, model registration, segmentation and mesh generation. In a subsequent step, we simulate the repositioning of facial bones using a 3D skull model of the patient. The resulting deformations are computed by finite element representations of the facial skin and soft tissue. This allows us to model a variety of effects and phenomena, including incompressibility or non-linearities. To facilitate numerical simulation and photorealistic visualization we designed various types of shape functions featuring a smooth representation of the facial surface. I will demonstrate the performance of the method and present the results of quantitative error analysis obtained from a clinical case study. A video animation further illustrates the procedure.

Color in context: from perception to image enhancement

Alessandro Rizzi, University of Milano, Dipartimento di Tecnologia dell'Informazione

For a long time color has been analyzed as a physical property of light and/or objects, without taking into account the characteristics of the human vision system (HVS).
The HVS, during the vision process, continuously performs various adaptation mechanisms, among them color and lightness adaptation. These adaptation mechanisms are responsible of the chromatic appearance of an object, which strongly depends on the scene characteristics, such as the light sources and the chromaticity and the mutual positions of the objects. This fact affects the analysis and the reproduction of digital images, acquired or made by synthesis.
Strictly related with lightness adaptation, is the "tone reproduction" problem, whose purpose is to give a robust and effective solution to a correct reproduction of high range lightness and color gamuts on limited range devices such as a monitor or an ink jet printer. In fact, the HVS operates at very different luminance levels (from 10 exp -6 to 10 exp 8 lux), while a display can reproduce only a restricted range (10 exp 2).
These and other problems have originated a new research field called "Color appearance" which scientific paradigm emphasizes the importance of visual appearance, extending the classical approach which considers only visual stimuli and light sources photometric and colorimetric properties, leaving in the background the perceptual properties of the HVS. In fact, pursuing color enhancement for commercial applications, several researchers investigate HVS computational methods to implement automatic color correction algorithms, with the purpose to produce pleasant images rather than correct image by a colorimetric point of view. It is clear that the notion of pleasantness, even if not quantifiable, is strictly correlated with principles of visual appearance.
A famous model of the HVS color perception is Retinex, due to Land and McCann. This theory is 40 years old, but has a renewed interest. It has been studied by many researchers and several different algorithm have been developed.
Starting from the Retinex approach, but with a completely different computational model, an alternative algorithm has been recently developed by our group. It is called ACE, for Automatic Color Equalization.
It is not a complete model of the HVS, since it performs only some of its mechanisms. Like the HVS, ACE is able to adapt to varying lighting conditions, and to extract visual information from the environment efficaciously. Its computational approach merges the "Gray World" and "White Patch" global equalization mechanisms, and adds local adaptation effects, by taking into account the spatial distribution of color information. ACE has shown promising results in solving the color constancy problem and performing an effective image dynamic data driven stretching. The promising results and its characteristics suggest other types of application.