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Item CCD-Camera Based Optical Beacon Tracking for Virtual and Augmented Reality(Blackwell Science Ltd and the Eurographics Association, 1996) Madritsch, Franz; Gervautz, MichaelWe introduce a scheme for optical beacon tracking using two CCD-cameras and LED beacons. Due to the sub-pixel accuracy of the beacon detection algorithm a very high precision can be achieved so that the tracking method is suitable for augmented reality applications. We describe the assembly of the equipment needed for the whole tracking system, the behavior of LED-beacons, and how three beacons can be combined to form a 6-DOF tracker. A report on our accuracy evaluation and its results are given. Furthermore we describe two application prototypes in which the tracker was incorporated and tested.Item The Personal Interaction Panel - a Two-Handed Interface for Augmented Reality(Blackwell Publishers Ltd and the Eurographics Association, 1997) Szalavari, Zsolt; Gervautz, MichaelThis paper describes the introduction of a new interaction paradigm to augmented reality applications. The everyday tool handling experience of working with pen and notebooks is extended to create a three dimensional two-handed interface, that supports easy-to-understand manipulation tasks in augmented and virtual environments. In the design step we take advantage from the freedom, given by our very low demands on hardware and augment form and functionality to this device. On the basis of examples from object manipulation, augmented research environments and scientific visualization we show the generality of applicability. Although being in the first stages implementation, we consider the wide spectrum of suitability for different purposes.Item Demand-Driven Geometry Transmission for Distributed Virtual Environments(Blackwell Science Ltd and the Eurographics Association, 1996) Schmalstieg, Dieter; Gervautz, MichaelWe present a strategy for rendering in distributed virtual environments. A geometry database is maintained by a server, while users invoke individual clients to interact with the environment. Instead of downloading a complete copy of the geometry data, the data is distributed on demand, thus gaining signifcant savings in network bandwidth. Our strategy combines several techniques, including levels of detail, progressive refinement and graceful degradation to deliver the data"just in time" over the network to the rendering process. The method allows operate on a tight resource budget, which important if attempting to use low cost systems for virtual reality applications.Item An Image based Measurement System for Anisotropic Reflection(Blackwell Science Ltd and the Eurographics Association, 1996) Karner, Konrad F.; Mayer, Heinz; Gervautz, MichaelThis paper introduces an image based method for measuring bidirectional reflectance distribution functions (BRDF). The measurement system uses a CCD camera connected to a workstation to capture images from the material under investigation. The evaluation of the BRDF is performed in an image processing step, gathering BRDF values with a broad range of incident and reflected angles, followed by a fitting process, where these values are approximated by a chosen reflectance model. Absolute BRDF values are obtained by the usage of a diffuse reflectance standard. It is shown that the proposed measurement system produces very reasonable results compared to accurate measurements. Thus, it is an easy and cost efficient way to measure material properties needed for physically based rendering algorithms.