Data Storage, Retrieval, and Management

Data storage, retrieval, and management:
The different types of information required for a GIS require storage which allows the information to be updated and queried for analysis by the user. There are two types of information to be stored; spatial data and attribute data.

Spatial data: Spatial data is usually stored as themes, layers, or coverages. The georeferenced spatial data is displayed in a GIS in its proper place in relation to other spatial data because of the georeference information attached to the data. An example could be the latitude and longitude in decimal degrees of Bonneville Elementary School in Pocatello, Idaho (42° 52' 14" N, 112° 26' 28" W). The latitude and longitude of this school is embedded in the file so it will be displayed in a GIS in its proper location in relation to other features in the city. Themes can be anything that are currently located on a traditional paper map, such as roads, rivers, cities, wells, forest boundaries, school district boundaries, etc., and they are all georeferenced.

Attribute data: Attribute data is the information about an object or feature. An example could be our school. Its name, location, what district, how many children attend each year, etc. Attribute data is usually stored in a database, tabular, or spreadsheet type format.

Data manipulation and analysis: A good system and/or software package allows the user to define and execute spatial and attribute procedures. This is commonly thought of as the heart of the GIS. Overlaying, buffering, modeling, and analysis are some of the methods used in building a coverage or project. It also takes the users knowledge to recognize what is seen in the resulting map and data.

Data output: Usually this is a map or graphic, which the user has generated after analyzing the data. Tabular data and reports can be generated as well to help explain the details seen in the map or graphic.