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OBJECT-ORIENTED GIS AND REPRESENTATION OF MULTI-DETAILED DATA
Govorov M.O., Khorev A.G.
Regional Center of Geoinformation Technologies of the Siberian Branch of the Russian Academy of Sciences
Universitetsky Ave. 3, Novosibirsk, 630090, Russia
Dept. of Cartography, Siberian State Academy of Geodesy, 10 Plahotnogo St., Novosibirsk, 630108, Russia
,
Commission IV, Working Group 6
KEY WORDS: Multi-Detailed Object-Oriented GIS; cartographic generalization.
PURPOSE
Object-Oriented Geographic Information System can be named as a system in which DBMS is used for restoring of
cartographic representation in a required level of detail corresponding to determined scale of map with the minimum
data duplication and data reduction. The concept of multi-detailed data directly connects with a concept of map
generalization.
The present article deals with the problem of creation of a Multi-Detailed Object-Oriented GIS (MGIS). Main attention
will be paid to problems of implementation of cartographic generalization (CG) in GISs. While designing any MGIS, it is
proposed to use Object-Oriented Approach (OOA), the latter being the most appropriate tools for implementation of
methods of CG in GISs. Issues of utilizing OOA properties at various stages of generalization decision-making are
discussed. The inner structure of the object-oriented model of MGIS spatial objects has been considered. Attached is a
flow-chart which reflects the main components and data interface of the MGIS. A number of MGIS object classes is
studied in detail, interface between MGIS objects and CG methods is presented. OOA can not sometimes be applied to
description of CG processes. That is why besides OOA it is necessary to use other intellectual approaches, as noted
below.
INTRODUCTION of knowledge; user graphic interface and OO analysis
technique (Helokunas, 1994).
Basing on personal experience and various works on Development or extension of a specialized OO DBMS
ACG and multi-detail imaging in MGIS, it becomes can become the basis of creation of a MGIS. An OO
evident that there is a need of supporting a unified model database is a base not only developed in the OO
of a single object in the GIS data base (Aasgaard, 1992, language but also a base storing objects with all their
Beard, 1991, Govorov, 1994, 1995, Grunreich, 1993, attributes, methods and interobject relations (Cattell,
Jones,1991, Khorev, 1996, Buttenfield,1991, van 1994). Such a base practically does not require DBMS
Oosterom, 1995, etc.). because all information about behavior of objects is
The problem of creation of MGIS is directly connected contained in the objects themselves as methods.
with the problem of automation of cartographic Usage of OO DBMS in conjunction with a decision-
generalization (CG). making system (DMS) will enable construction of a
Digital CG is utilization of the mechanism of abstraction unified MGIS. Such a system will enable it to evaluate
as applied to real-world objects with the idea to formulate the use of OO DBMS objects and to create necessary
a reality image with the use of simplification and imaging models disregarding the tasks set forth.
supplement. This abstraction is of multi-factor character. Application of OOA for description of CG processes in
That is why the CG process in GIS can be automated digital media is justified by the fact that many OOA
only with the use of methods of data processing utilized characteristics can easily describe the process of
in intellectual systems (Buttenfield,1991, Govorov, 1995, abstraction of an OO entity in a map. Here the very
Zhang,1993) ^ Attempts to model cartographic notion of a CG process is understood as design of an
generalization within the framework of geo-relational OO model of a geophysical phenomenon and OOA to
approach lead only to development of interactive actual implementation of cartographic modeling during
cartographic generalizator designed for creation of visualization.
cartographic image of an object, not of a whole digital
cartographic model of the related phenomenon
(Govorov,1995). In a relational model are stored OBJECT-ORIENTED APPROACH IN GIS
relations not between separate objects but those
between types of data. Different data types imply The concept of OOA is widely used in program
different tables. ; languages, DBMS, information systems, etc. Such
One of the most applicable approaches can be object- concept is also used at GIS construction (Gunter, 1994,
oriented approach (OOA) (Gunter, 1994, Milne,1993, Milne, 1993, Helokunas, 1994, Stonebraker, 1986,
Rumbaugh, 1991, Vijibrief, 1992, etc.) Such approach Vijidrief, 1992, etc.).
does not presupposes mere usage of OO programming Main characteristics of OO GIS are as follows:
technologies, but also application of such technologies to 1) object-centered data model:
such areas as OO DBMS, system CADs; representation
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996
