The National Effort for the Improvement of Air Quality in Australia - Thesis Example

A geo-database is a relational database that stores geographic information system (GIS) data to collect tables. Geo-databases contain vector and raster data and their associated attributes. Users interact with geo-database data in the same way as they interact with file-based data (e.g., coverages or shapefiles) through ArcGIS clients like ArcMap. However, the geo-database centralizes the GIS data for improved data administration and allows the creation of validation rules to help prevent errors from being introduced into the data.

Geo-databases come in two variants: personal and enterprise. Personal geo-databases are stored in a Microsoft Access database file and are intended for use by a single user. Multiple users may read the personal geodatabase, but one user can only make edits at a time. Large organizations may choose to implement the geo-database in a more powerful relational database management system (RDBMS) served by ArcSDE software, allowing multiple simultaneous edit sessions, larger data volumes, and faster transactions.

Regardless of the implementation, the geo-database supports a variety of validation rules to help enforce data integrity. Attribute domains may be applied to fields to help prevent illegal attribute assignment, relationship rules may be used to help prevent illegal thematic relationships (e.g., putting a warehouse on the residential property), and topology rules may be implemented to find errors between spatial features (e.g., bus routes that are not coincident with city streets). Working with a geodatabase topology is much more flexible than working with coverages because once the topology has been created, you can stop at any point in the process.

In addition, when you work with the geo-database, you have the choice between assigning or not assigning topology to your data. You can also pick which topology rules you want to use. The coverage model does not offer this flexibility. After determining the data to store in your database, your next task is to select feature classes and organize these feature classes into layers. The conceptual design is a top-level concept of how the database will work.