Ludwig-Maximilians-Universität München, Institut für Informatik
Technical Report 93-24
- TITLE:
-
Query Processing of Geometric Objects with Free Form Boundaries
in Spatial Databases
- DATE:
-
November 1993
- AUTHORS:
- Hans-Peter Kriegel
<kriegel@informatik.uni-muenchen.de>
- Stephan Heep
- Andreas Fahldiek
- Norbert Mysliwitz
- Institut für Informatik
- Universität München
- Leopoldstr. 11B
- D-80802 München (Germany)
- KEYWORDS:
-
spatial database systems, spatial query processing,
spatial objects, free form boundaries, B-spline, Bizier curves
- ABSTRACT:
-
The increasing demand for the use of database systems as an
integrating factor in CAD/CAM applications has necessitated the development of database systems with appropriate modelling and retrieval capabilities. One essential problem is the treatment of geometric data
which has led to the development of spatial databases. Unfortunately,
most proposals only deal with simple geometric objects like multidimensional points and rectangles. On the other hand, there has been a rapid development in the field of representing geometric objects with free form
curves or surfaces, initiated by engineering applications such as mechanical engineering, aviation or astronautics. Therefore, we propose a concept for the realization of spatial retrieval operations on geometric objects with free form boundaries, such as B-spline or Bizier curves, which
can easily be integrated in a database management system. The key concept is the encapsulation of geometric operations in a so-called query
processor. First, this enables the definition of an interface allowing the integration into the data model and the definition of the query language of
a database system for complex objects. Second, the approach allows the
use of an arbitrary representation of the geometric objects. After a short
description of the query processor, we propose some representations for
free form objects determined by B-spline or Bizier curves. The goal of
efficient query processing in a database environment is achieved using a
combination of decomposition techniques and spatial access methods.
Finally, we present some experimental results indicating that the performance of decomposition techniques is clearly superior to traditional query processing strategies for geometric objects with free form boundaries.
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Robert Stabl
(28.11.1994)