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Heirarchical Data Model for a Relational Database based Geographic Information System

IP.com Disclosure Number: IPCOM000118530D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2005-Apr-01

Publishing Venue

IBM

Related People

Dugan, RF: AUTHOR

Abstract

Disclosed is a Relational Data Model for a Geographic Information System (GIS) that supports inheritance. The inheritance model is superior to conventional relational models because it recognizes class relationships that exist in GIS. An implementation of the inheritance model is proposed using relational technology. An actual GIS data model is presented. This model provides support for the three major areas in a GIS: spatial data, application development, and administrative tasks.

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Heirarchical Data Model for a Relational Database based Geographic
Information System

      Disclosed is a Relational Data Model for a Geographic
Information System (GIS) that supports inheritance.  The inheritance
model is superior to conventional relational models because it
recognizes class relationships that exist in GIS.  An implementation
of the inheritance model is proposed using relational technology.  An
actual GIS data model is presented.  This model provides support for
the three major areas in a GIS:  spatial data, application
development, and administrative tasks.

      The evolution of GIS, Computer Aided Design (CAD), and Computer
Aided Manufacturing (CAM) has required that information be stored and
retrieved from non-proprietary databases within an enterprise.  This
information is very complex.  In particular, the commonality between
basic tables that model real world objects in GIS/CAD/CAM is
difficult to represent in most relational databases.  For a GIS,
examples of objects include:
  o  A road
  o  A political boundary
  o  A user interface
  o  A user-defined table
  o  System administrative data

      One of the main obstacles to modelling these tables with
relational technology is the ability to recognize that elements of
each table are common across many tables.  The trend for modelling
this commonality has been the adoption of object-oriented databases
and software by many GIS/CAD/CAM systems.  Businesses have not
benefitted from this direction, however, as most enterprises use
relational databases.

      The problem with relational databases is that their table/view
mechanism does not provide the flexibility to define a single view
across several tables without a relational join.  Consider the
following:
  o  A road table has "ID", "TYPE", "LOCATION", and "LENGTH"
      attributes.
  o  A political boundary table has "ID", "TYPE", "LOCATION",
      "PERIMETER"  and "AREA" attributes.

What is proposed is:
  o  An Inheritance Data Model for a GIS.
  o  A mechanism for storage/retrieval of said data model
      using a relational database.

The following represents the basic description of the inheritance
data model used in GIS:

      General Concepts

      GIS data includes all the enterprise assets (such as parcels,
cables, valves, or highway sections) that are modelled and maintained
as GIS data, as well as application and operational data (e.g.,
Macros, Display Rules, User Profiles, and Device Characteristics)
used by the GIS  software and GIS applications.

      For example, an enterprise may choose to model and maintain
land parcel information as GIS data in a GIS.  The GIS users and
application developers can operate on parcels and the attributes of
parcels much as they would access other data in the relational
database.  In addition, non-GIS users and Corporate applications can
access the parcel data through the relational views an...