An Rdbms-supported, Web-based, 3d Gis, Visualisation and Analysis Tool

The increasingly widespread availability of spatial data through formal infrastructures (governmental SDI, national clearinghouses, geoportals) and less formal sources (corporate intranets, websites …) has heightened awareness of the importance of and possibilities in spatial data mining. Successful spatial data mining requires highly functional visualisation tools for representation and analysis. The flowline from spatial database, through browsing, querying and searching, to access, delivery and final visualisation must be examined to ensure its efficiency. This paper describes a tool which brings 3D GIS functionality to a standard web browser, without the need for specific plug-ins. We present an online visualisation tool, GeoDOVE (Geospatial Database Online Visualisation Environment), which is a 3D visualisation environment for viewing and analysing spatial information using an internet browser. GeoDOVE is integrated with a database server and web browsing software, and offers significant 3D spatial data display capability. GeoDOVE connects to candidate data files, their layers and metadata. Querying can be undertaken by visual examination of data file properties and spatial extent. GeoDOVE obtains data from an Open DataBase Connectivity(ODBC-) compliant online-RDBMS, such as MySQL™ or MS SQL SERVER™, database server via the internet (or offline-RDBMS such as Microsoft™ Access). As a free piece of software MySQL™ is of particular interest due to its widespread use. GIS data files are uploaded onto the database server over the web, directly via an ODBC bridge. GeoDOVE uses Java DBC to access the data from the server without the need for middleware to communicate with the database. The system can handle data in commonly used file formats such as ESRI Shapefiles, worldfiles, Geography Markup Language, VRML etc. The commitment to free open-source technologies is maintained in the development of visualisation capabilities using Java 2™ and Java 3D™ (available free of charge from java.sun.com). With particular concentration on handling 3D data, GeoDOVE allows for draping of images over terrain surfaces, feature extrusion for urban area representation, realtime ‘fly-throughs’ and dynamic data rendering. The real-time linkage of the visualisation tool with the database over the web allows for standard querying of the database by position and by attribute. In addition, linkage to multiple database servers (for example, using ArcSDE) is possible, as is database integration and conflation. The architecture of the GeoDOVE system is described, along with examples of its use with a range of spatial databases served in different ways and integrated to allow for visualisation and ‘added value’.