R-trees for organizing and visualizing 3D GIS databases

Abstract

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. With 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). With 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). Both 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 © 2000 John Wiley & Sons, Ltd.