Entwurf eines Rahmensystems für mobile Augmented-Reality-Anwendungen

Augmented Reality (AR) ist eine eng mit der Virtuellen Realität (VR) verwandte Technologie. Der Anwender taucht dabei nicht komplett in eine virtuelle, computergenerierte Umgebung ein, sondern verbleibt in seiner realen Umgebung, die mit virtuellen Objekten erweitert wird. Diese virtuellen Objekte werden dabei möglichst passgenau in das Blickfeld des Anwenders eingeblendet. Wichtige klassische Forschungsthemen im Bereich der AR sind das sogenannte Tracking, d.h. die Bestimmung der Blickrichtung des Anwenders, die korrekte Beleuchtung der virtuellen Objekte, sowie Schattenwurf und Verdeckung zwischen realen und virtuellen Objekten. Ein Thema, das in den vergangenen Jahren immer stärker in den Vordergrund gerückt ist, ist die Frage nach der Systemarchitektur von AR-Systemen. Mit dieser Fragestellung befaßt sich die vorliegende Arbeit. Zunächst werden existierende VR- und AR-Systemarchitekturen analysiert. Ausgehend vom existierenden VR-Standard VRML bzw. seinem Nachfolger X3D wird dann untersucht, um welche Bestandteile dieser Standard erweitert werden muß, um auch für mobile AR-Anwendungen genutzt werden zu können. Dabei liegt der Fokus auf dem Gerätemanagement, der Kommunikation im Netzwerk und der Entwicklung und dem Debugging mobiler AR-Anwendungen

System Architecture of a Mixed Reality Framework

In this paper the software architecture of a framework which simplifies the development of applications in the area of Virtual and Augmented Reality is presented. It is based on VRML/X3D to enable rendering of audio-visual information. We extended our VRML rendering system by a device management system that is based on the concept of a data-flow graph. The aim of the system is to create Mixed Reality (MR) applications simply by plugging together small prefabricated software components, instead of compiling monolithic C++ applications. The flexibility and the advantages of the presented framework are explained on the basis of an exemplary implementation of a classic Augmented Realityapplication and its extension to a collaborative remote expert scenario

Managing Data Flow in Interactive MR Environments

In this paper the concept and design of a software framework which provides a transparent data flow for interactive Mixed Reality (MR) applications is discussed. The design was affected by our demands on platform independency, simplicity, network transparency, maximum performance and availability of runtime debugging facilities. Our software framework tries to simplify the development of MR applications by using the concept of a data flow graph. The developer builds such a graph from a library of small software components that communicate via the edges of the graph

Real-time virtual cables based on kinematic simulation

We present an algorithm for the real-time simulation of virtual cables using inverse kinematics. A cable is modeled by consecutive cylinder segments of equal size. The segments are connected by ball joints. At every joint there is a spiral spring acting against the excursion of the joint. Given a start and an end position of the cable, the algorithm calculates the shape of the cable that leads to minimal total energy. The total energy is the sum of the potential energies of the segments and the elastic energies of the springs. First, the algorithm calculates a cable with minimal total energy consisting of two segments. This is taken as a starting basis for the computation of a cable consisting of four segments. At each following step, the number of segments is doubled and a new shape of the cable is calculated based on the solution of the previous step. The great advantage of this approach is the easy accommodation of the solution exactness to the available computation time. If the user of the VR application is moving the cable, he gets a fast but rough feedback. If he stops moving it, he/she gets an exact shape