Many effective automatic surface simplification algorithms have been developed. These automatic algorithms create very plausible results in many cases, but at very low levels of detail they do not preserve the visual appearance of the original model very well. This could be improved if surface simplification algorithms were able to make use of semantic or high-level meaning of models. The idea of our new method using a morph-target-based surface simplification is to use distance information inside the morph-targets to acquire the relative importance of different surface regions without user guidance. Using this additional input the model is simplified by using modified quadric error metrics.

Virtual humans and avatars are enhancing a lot of current computer applications. This leads to the usage of complex characters for presentations, e-learning tasks and virtual reality applications. Often it might be suitable to have the possibilty of scaling the character to avoid performace problems or to fit the personal needs of the user. An universal architecture to control the scaling of the character is presented. It is based on an Adaptation Engine and different scalability modules which can be configured to the preferences of the user and the graphical system.

Virtual humans and avatars are enhancing a lot of current computer applications. This leads to the usage of complex characters for presentations, e-learning tasks and virtual reality applications. Often it might be suitable to have the possibilty of scaling the character to avoid performace problems or to fit the personal needs of the user. An universal architecture to control the scaling of the character is presented. It is based on an Adaptation Engine and different scalability modules which can be configured to the preferences of the user and the graphical system.

We describe the rendering functions of the Augmented Reality System GEIST. GEIST is a 3D based narrative education system, an installation at the castle of Heidelberg, Germany, based on digital storytelling, GPS localization and interactive rendering. The rendering is interactive, as it is driven by user interaction, e.g. GPS position, head movement and line of sight as well as direct interaction (yes/no to questions of Virtual Characters).

An ongoing research topic is to build suitable visualization architectures for anthropomorphic conversational user interfaces which will run on different devices like laptops, PDAs and smart phones. One interesting way to handle the performance restrictions on small and mobile devices are scalable avatars and animations. An idea to speed up our animation system based on morph targets is presented, to achieve this the number of animation weights for the morph targets is reduced dynamically. This method is optimized by regarding the graphical structure and dependancies of the morph targets.

The aim of this study was to evaluate the initial staging and restaging of Hodgkin's disease (HD) according to histopathologic subtype (HST) using fluorine-18-deoxyglucose-positron emission tomography (PET). Special attention was paid to the accuracy of PET for detection of bone marrow infiltration (BMI). 44 patients with HD (m:f = 28:16, mean age 36 +/- 15 years) underwent PET; 16 were primary stagings and 28 restaging examinations. PET results were compared with methods of conventional staging including computed tomography (CT) and bone marrow biopsy. Viable tumor tissue was detected by PET in 25/44 cases, 16 nodular sclerosis (NS), 4 mixed cellularity (MC), 3 lymphocyte predominance (LP) and 2 cases with a nonclassified subtype (NC). FDG tumor uptake, measured as standard uptake value (SUV), ranged from 1.7 to 13. Maximum SUV in NS was 5.2 +/- 1.5 (2.5-7.3), 3.2 +/- 2.4 for MC, 2.6 +/- 0.7 for LP, and 9.1 +/- 3.8 for NC, respectively. In 7% of all patients (3/44) bone marrow infiltrations were detected by PET. PET is known for its superior detection of viable tissue in HD. In this study it was shown that HST does not influence the intensity of glucose metabolism, although 2 patients with NC showed the highest SUVs. In addition PET accurately detected focal BMI and may thus be applied before BMB to guide its optimal use.

Computers are moving more and more from the desktop into our everyday life. Today's challenge is to build a suitable visualization architecture for anthropomorphic conversational user interfaces which will run on different devices like laptops, PDAs and smart phones. Concrete implementations as part of conversational interfaces are User-Interface Avatars which are anthropomorphic representatives on the base of artificial 3D characters. The existing system methods, the graphical output chain and different optimization strategies are discussed.

A woman was referred for fluorodeoxyglucose positron emission tomography for the staging of a malignant melanoma. Although no signs of metastatic melanoma were evident on the whole-body scan, focally increased uptake within the femoral metaphysis was noted. Radiographic and magnetic resonance examinations revealed an enchondroma as the cause of the increased uptake. Histopathologic verification was obtained. The final diagnosis was actively proliferating enchondroma. A grade I chondrosarcoma could be ruled out. Enchondromas may be responsible for focally increased FDG uptake in bone lesions and must be considered when positron emission tomographic scans obtained with FDG are evaluated in cancer staging.

The staging of Hodgkin's lymphoma (HL) is crucial for an optimal therapy, and fluorine-18-deoxyglucose-positron emission tomography (FDG-PET) is increasingly used in this regard. However, there is still a scarcity of available data on the staging of HL. Twenty-eight consecutive patients with newly diagnosed HL were included in this study. PET results were compared with conventional staging, including clinical workup, computerized tomography (CT) and sonography. Evaluation was focused on the description of involved lymph node (LN) regions or organs rather than on a lesion-by-lesion analysis. In supradiaphragmal LN, the results of PET and CT scans were positive in 26% and negative in 68% of cases. Furthermore, PET was positive in 5% (CT negative), and CT showed enlarged LN in 1% of cases (PET negative). In infradiaphragmal LN, PET/CT results were positive in 10% and negative in 88% of cases. In 2% of cases, PET showed additional foci, while in 1% the CT was positive. PET changed the staging in 21% of cases (4 up-stagings, 2 down-stagings) and this was confirmed during follow-up. PET should therefore be routinely used for staging HL until larger clinical studies can demonstrate patients who may not require this additional investigation or those patients who are reliably staged on the basis of PET alone.

With the advent of software agents and assistants, the concept of so called conversational user interfaces evolved, incorporating natural language interaction, dialogue management, and anthropomorphic representations. Today's challenge is to build a suitable visualization architecture for anthropomorphic conversational user interfaces, and to design believable and appropriate face-to-face interaction imitating human attributes such as emotions. The system is designed as an autonomous agent enabling easy integration into a variety of scenarios. Architecture, protocols, and graphical output are discussed.

Presents the VPARK (Virtual Park) system, which includes a networked virtual environment (NVE) system called W-VLNET and an "attraction building system" that is able to create and modify the attractions used in the NVE. Both systems have been developed in the Windows NT environment. The paper outlines the techniques for communication, scene management, facial and body animation, and general user interaction modules. The use of VRML97 and MPEG-4 SHNC is overviewed for the purpose of outlining the compatability of the system with other similar virtual reality systems. The software provides realistic virtual actors as well as sets of high-level actions that are applicable to them in real-time. Related issues on obtaining actor models and animating them in real time are presented. The creation process of an attraction incorporates assembling animation units through a timeline. Using this software, the users are able to bring their own scenario-based applications into a shared virtual environment.