Summary: External­Memory Algorithms for Processing Line Segments in
Geographic Information Systems \Lambda
Lars Arge y Darren Erik Vengroff z Jeffrey Scott Vitter x
Dept. of Computer Science Dept. of ECE Dept. of Computer Science
Duke University University of Delaware Duke University
Durham, NC 27708 Newark, DE 19716 Durham, NC 27708
USA USA USA
January 1998
Abstract
In the design of algorithms for large­scale applications it is essential to consider the problem
of minimizing I/O communication. Geographical information systems (GIS) are good examples
of such large­scale applications as they frequently handle huge amounts of spatial data. In this
paper we develop efficient new external­memory algorithms for a number of important problems
involving line segments in the plane, including trapezoid decomposition, batched planar point
location, triangulation, red­blue line segment intersection reporting, and general line segment
intersection reporting. In GIS systems, the first three problems are useful for rendering and
modeling, and the latter two are frequently used for overlaying maps and extracting information
from them.
1 Introduction
The Input/Output communication between fast internal memory and slower external storage is

Source: Arge, Lars - Department of Computer Science, Aarhus Universitet

Collections: Computer Technologies and Information Sciences