Michael Gruber

R‐trees for organizing and visualizing 3D GIS databases

With the migration from 2D to 3D geographical information systems (GISs), the amounts of data to manage grow substantially. At the same time, 3D real-time rendering is necessary to provide a convenient user interface. Traditional GIS data management functions are too slow for this purpose, while computer graphics algorithms fail to deal with the sheer amount of data efficiently. In this paper we present LOD-R-trees, a new data structure which elegantly combines R-trees with LODs (levels of detail). Two applications demonstrate the versatility of our approach. n n n n n nWith the Vienna Walkthrough System one can virtually walk through Vienna, the capital of Austria. The geometric model consists of about 20,000 blocks of buildings, covering about 75% of Vienna (150 km2 out of 200 km2). n n n n nWith the Styria Flyover System one can virtually fly over Styria, a province of Austria. The digital model covers Styria and parts of its adjoining provinces (30,000 km2); it is based on a digital terrain model (DTM) consisting of more than 23 million triangles and of 50 Mbyte texture data (satellite images). n n n n n n nBoth applications provide progressive rendering and dynamic performance adjustment. On an SGI 02 they deliver about 10 frames per second. Our approach demonstrates that efficient algorithms make a fast 3D GIS user interface possible without spending a fortune on hardware. Copyright

The Styria Flyover-LOD management for huge textured terrain models

With the Styria Flyover one can virtually fly over Styria, a province of Austria. The countryside is characterized by a mixture of rather flat regions in the south east and mountains up to 3000 m in the north west. The digital model covers Styria and parts of its adjoining provinces (30,000 km/sup 2/); it is based on a DTM consisting of more than 23 million triangles and on 50 Mbyte texture data (satellite images). The framework combines an R-tree data structure with efficient LOD management (automatic mesh refinement), progressive rendering and dynamic performance adjustment. On a SGI O2 it delivers more than 8 frames per second. The authors approach demonstrates that efficient algorithms make a fast 3D GIS user interface possible without spending a fortune on hardware. The paper focuses on techniques and data structures to maximize the performance of visualization.

Managing Large 3D Urban Database Contents supporting Phototexture and Levels of Detail

We present a method to handle large database contents for visualization of urban scenes. These data consist of geometry (vector data) and phototexture from images (raster data) which have different size and different characteristics. A high emphasis is given to the possibility of remote use (client/server system) and therefore of special concepts to manage, retrieve, transfer and visualize data from local and remote sites.

Urban data management — A modern approach

The urban data management of the outgoing 20th century shows strong emphasis in creating three-dimensional descriptions of cities, developing methods to maintain and up-date these data, and in exploiting the Web for broad distribution and presentation. The so-called CyberCity not only shows data in three dimensions but also presents photorealistic surface description, exploiting phototexture from aerial and terrestrial images. The benefit of this high level quality is of broad appeal, which makes the CyberCity a tool for various applications, such as decision making, mission planning, simulation, training, path finding and many others. Remote and local access to the data, fast interaction and electronic links to other urban information systems turns this into a concept of a hypermedia database system, which is the unavoidable next step in improving the data for the management of our growing cities.

Plazentafunktion – Nährstofftransport – Gasaustausch

Die vorrangigste Aufgabe der Plazenta ist es, den wachsenden Fetus mit Energie in Form von Nahrstoffen und mit Sauerstoff zu versorgen. Auf diese beiden Funktionen wird im folgenden Kapitel im Detail eingegangen. Die Versorgung mit Nahrstoffen ist in den Transport von 1) Lipiden und Fettsauren, 2) Glukose, 3) Proteinen und Aminosauren sowie 4) den Transport von Spurenelementen und Mineralien untergliedert. Abschliesend wird der maternofetale Gasaustausch von Sauerstoff und Kohlendioxid sowie die besonderen Eigenschaften des fetalen Hamoglobins beschrieben.

Forschungsaspekte und In-vitro-Modelle

Da es kein adaquates Tiermodell zur Untersuchung der humanen Plazentaentwicklung gibt, beruhen Erkenntnisse zu zellbiologischen Ablaufen der Plazentaentwicklung, wie etwa Aspekte der Trophoblastdifferenzierung, aber auch immunologische und endokrine Funktionen der humanen Plazenta, zu einem wesentlichen Anteil auf In-vitro-Untersuchungen an unterschiedlichen Zell- und Gewebskulturmodellen.

Self-calibration of a 3D object scanner based on a CCD linear sensor

This paper describes the practical aspects of CCD-line set up and calibration for a 3D Objectscanner based on shape from stereo which was designed and produced at our Institute. This calibration is important if one wants to achieve best results with a scanner. We present an imaging system based on a single CCD-linear sensor and we provide a two-step self-calibration procedure. The results of our calibration method allows to measure object points of an accuracy better than 0.1 mm in 3D space. The self-calibration is repeatable and is suitable to be performed at the users site by using the 3D Objectscanner and the 3D calibration target.