The integration of spatial datasets for network analysis operations


Application development
Application development took place in several phases. The first phase was the development of mechanisms for the export of data from a variety of sources and formats. Thus a tool was developed to export data from ArcView via ODBC using SQL. GE Smallworld Magik application language was used to develop a similar system using COM (Component Object Modelling - a Microsoft software architecture) [14] and SQL for export from GE Smallworld VMDS (Version Managed Data Store).

The application to display, query and modify the relational database was developed in Java. Several tools were created for supporting the application: data query, manipulation, display and analysis functions.


Figure 9. Application Model

In the main application JDBC was chosen to facilitate database connection and to extract data into the application. The JDBC-ODBC bridge and an ODBC driver, Type 1 JDBC driver [20], was used for the database connection.

Many basic functions were developed in the application tools: selection, intersection, snapping, transformation, and so on. The GUI was developed from AWT and Swing packages provided as part of the Java platform. The tool to build the topology based on the connectivity rules defined in the family and stored in the database was developed. The network analysis functions were also created. There are two basic functions for network analysis: network trace, and shortest path. The Dijkstra [3] algorithm was used for both network analysis functions. The GUI of the application is shown in the Figure 10.



The implementation has been tested both with simulated data and a network of transport data extracted from a sample GE Smallworld dataset of the Cambridge area. The network connectivity rule in the “road” manifold was transferred to the network “road” family. The topology of the network family was built up, and then the network analysis was tested.

Conclusion
This paper describes a conceptual generic data model for the handling of spatial and topological feature data. The limited implementation that has been completed has demonstrated the validity of the model using a variety of test data sets from several proprietary formats. The network analysis functions implemented so far have proved the validity of the data model in respect to the handling of topological analysis for directional and non-directional networks. The concept of the network “family” of features presents a user-friendly interface to the assignment of network connectivity and overcomes several issues that face integration of topological and non-topological datasets.

Future work will focus on data integration, and an implementation with extended data sets. The mechanisms for checking data duplication (where the same feature is stored in more than one original dataset) will be investigated. Several scenarios of network applications will be tested. Finally more work is required to serve the final application in an “application server” environment running over a private or public network using web technologies.

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