Frank Goetz

Real-Time Marching Cubes on the Vertex Shader

In this paper we propose a new approach for visualizing volumetric datasets by their isosurfaces. For an interactive isosurface reconstruction an optimized version of the well-known marching cubes algorithm is used. We extend the original algorithm by an additional vertex shader program. Contrary to other hardware-accelerated solutions our program is not based on a tetrahedral algorithm and thus the implementation for structured grids is more effective. Furthermore, surfaces of time-varying datasets at distinguished threshold values can be extracted in real-time.

A Breadth-First Approach for Teaching Computer Graphics.

Two themes of computer graphics, namely computer-generated color and computer-generated visualization, are introduced in a teaching/learning tool using a breadth-first approach. The breadth-first approach provides a holistic view of the topics to teach, aids in interdisciplinary teaching and is equally motivating to male and female students. The breadth-first approach has now been used for several years and we can also report on evaluations of the teaching/learning tool.

An XML-based visual shading language for vertex and fragment shaders

This paper presents a new system for the visual development of complex vertex and fragment shaders. The system makes usage of the advantages of visual programming languages. The core of the system is a Java program. With this program users can develop and test dataflow diagrams that describe the functionality of OpenGL ARB vertex and fragment programs. To get a graphical feedback the system is able to display rendered and shaded scenes immediately. The rendering of these three dimensional scenes will be done with the common Java-OpenGL binding GL4Java. Further on Cg4Java, a new binding for connecting Java to NVIDIAs High-Level Shading Language C for graphics (Cg) was developed. For an easy and fast way of verification, and for the possibility of a future integration into XML based 3D formats like Extensible 3D (X3D), the whole topology of the dataflow diagrams will be stored in XML. The concept of shader programming with dataflow diagrams and the architecture of our system will be described in detail. For a better understanding two examples will be presented and explained.

Collaboration by illustration: real-time visualization in Web3D

Graphical representation of complex data sets is an important method for supporting scientific collaboration. Following this idea, we developed a novel Web3D-based visualization framework that supports synchronous as well as asynchronous cooperation, even of spatially separated scientist. Our open Visaar framework open-source technology and combines innovative techniques from the area of computer-generated visualization with modern achievements of CSCW (Computer Supported Cooperative Work). Therefore, we extended OpenSG with the functionality for supporting cooperative and remote features. OpenSG is a portable scene graph system to create real-time graphics applications. openVisaar is designed to accompany state-of-the-art CSCW systems in the collaboration process by embedding the visualization features into the co-operation environment. For this purpose openVisaar provides a rich set of interfaces. By combining both worlds -- visualization and CSCW - users of our system get an up-to-date all-in-one solution for collaborating with real world data.

A Framework for Video-based and Hardware-Accelerated Remote 3D-Visualization

This paper presents a framework for video-based and hardware-accelerated remote 3d-visualization that produces and delivers high quality video streams at an accurate frame rate. The framework is based on the portable scenegraph system OpenSG, the MPEG4IP package and the Apple Darwin Streaming Server. In realtime generated visualizations will be multicast as an ISO MPEG-4 compliant video stream over the RealTime Streaming Protocol from a server to a client computer. On the client computer a Java program and an ISO MPEG-4 compliant video player are used to interact with the delivered visualization. While using MPEG-4 video streams we can achieve high image quality at a low bandwidth.

openVisaar: Enriching Cooperative Visualization by Combining Open Technologies

In this paper we present a new client-server based visualization framework called openVisaar. For remote visualization encoded video streams are multicast from each cluster client node to the remote application with RTSP (Real Time Streaming Protocol). At the remote site only an ISO-compliant MPEG-4 video player software is needed to decode the video stream. By supporting remote video streams spatially separated working partners have the possibility of synchronous collaboration with our visualization system. For navigation and interaction at the remote site openVisaar offers different client software. Navigation and collaborative interaction can be enhanced with an additional Augmented Reality support. Only components that can be used freely for non commercial purposes are integrated.

sTeam3D: bringing together virtual communities and CSCW

Today CSCW systems are used in various scientific, economic, and industrial areas. The logical next step is that collaborators not only want to work together by sharing documents or by communicating via mail or chat. Rather it would be more interesting to meet colleagues, business partners, and customers in a virtual world, e.g. to discuss design and look of various products or concepts in 3D space and in real-time. Thereby, it is important that the whole cooperative functionality remains available. Most developments that bring a virtual community to the computer desktop are proprietary solutions that only partially contain CSCW features. In order to solve this problem and to provide a satisfying and functional virtual environment our aim was the development of an X3D-based Web3D client for a sophisticated CSCW system. As a server system we chose sTeam, a free CSCW system that is part of the Debian Linux distribution. Hence, virtual communities are able to use sTeam and our 3D client sTeam3D to get a fully featured CSCW environment.

Visual shaditor: a seamless way to compose high-level shader programs

Visual Shaditor is a platform independent tool for developing complex vertex and fragment shaders. The results can be compiled directly as Cg or GLSL programs. The shaded 3D scene will be rendered and displayed immediately in a preview window. The system makes usage of the advantages of visual programming languages, particularly the use of data flow diagrams.