What are Geographic Information Systems (GIS)?
A Geographic Information System (GIS) is a collection of hardware and software for managing geographic (spatial) information. It is estimated that about 85% of the information managed by cities and counties is geographically referenced (i.e. located on the Earth) in some way, such as the location of a building shown on a map. Examples of geographic information are addresses, parcels, school district boundaries, a road network, land use patterns, buildings, and utility locations.
The definition of GIS varies depending on specific applications, but generally it is described as a computer-based system with the ability to store, retrieve, modify, analyze, and represent geographic data as useful information. A GIS links map information (spatial data) with tabular information (stored in a relational database) about particular features on the map. A GIS, using the information stored in the relational database, can tell you how many feet of water main, the number of hydrants, and a breakdown of size (diameter) and material of water main. This information can be used to create a map of water mains color-coded based on size stored in the database or a report can be printed.
GIS provides current information on
land ownership and utility locations.
(Click the photo for a larger view.)
A GIS can be useful for relating mapped features and their attributes (non-graphic information associated with features) in two ways. First, the actual feature from a map, a sewer manhole for example, displayed on a computer screen may be pointed at electronically and used to access and display all of the attributes contained in the computer's database regarding that feature - the year it was installed, its material, diameter and capacity, etc. Second, the database itself can be queried to display only those features selected in a way that may give it meaning. An example of this is choosing all parcels of land selling for between fifty to sixty thousand dollars in the last year, delineating the areas where the highest rate of real estate transactions occurred in that price range.
Many government agencies, including the Village of Gurnee, are utilizing GIS because it offers a way of understanding and dealing with complex spatial problems by organizing the data, viewing their spatial associations, performing multiple analyses, and synthesizing results into maps and reports.
GIS technology is very useful, allowing many Village departments (and the public) access to the same basemaps and database. This means that each department does not have to keep separate versions of other department's maps and data in order to use them for their own agency's needs. Features or attributes need to be modified and updated on only one basemap and database and then be shared by everyone. Departments can portray mapped information at whatever scale they require, using the colors or symbols they want and accompany the maps with text and reports tailored to meet their needs.
What are GIS Efforts at the Village of Gurnee?
In order to coordinate the Village's spatial information needs across departments, development of a GIS is underway. The project incorporates information from aerial photography, surveying, plats, field work, and existing textual data into a useful integrated system. Map information such as parcels, zoning, topography, utilities, and buildings with database information on each of the features identified on the map have been entered into the GIS. This provides a consistent foundation for specific department data.
Improvements in the detail and accuracy of the Village's street, zoning, water, sanitary, and storm base maps are a direct benefit. Providing staff with a single, integrated system containing all types of geographical data helps them better serve the public and those contractors/developers we do business with. Also improved, are inventory and records of infrastructure items such as streets, hydrants, manholes, and water/sewer mains.
An internal website, available to all Village employees, provides access to GIS maps and data. This site was created in 2003 and has undergone several revisions in order to improve it’s usefulness to staff. The application allows staff to search for specific properties, view scanned documents (plats, sewer televising videos), and print maps.
GIS data is also used for the Police Department’s 911 system. The data is imported into the 911 system and used to validate the location of incoming 911 calls and to plot this location on a map.
Aerial photography provides a 'real-world' view of specific areas. (Click photo for larger view.)
The “hub” of the GIS network at the Village of Gurnee consists of one server, located at the Village Hall, that houses the SQL Server database and GIS server-based software (ArcGIS Server). This server also acts as a files server to store scanned documents such as plats (subdivisions, easements, annexations, etc) and utility connection drawings that are linked to GIS map data.
The GIS network also consists of several PC’s, located in various departments, loaded with desktop GIS software; and several printers and large-format plotters.
The Village also uses a Trimble Global Positioning Systems (GPS) unit to collect GIS data in the field. Using this handheld unit, one person can collect the location of a specific feature (hydrant) and information about that feature (hydrant type, manufactured year, etc) at the same time.
The Village uses ESRI software to build and maintain the GIS database. The software is both server (run on a Village/department server) and client (run on a specific computer) based.
The Village uses ArcIMS/ArcGIS Server to support the Village’s Intranet On-Line Mapping Site. This site allows anyone to access GIS information through Internet Explorer. The Village uses ArcGIS desktop software, loaded on a specific computer, for those who need a more powerful software solution. This desktop software allows users to analyze spatial data, perform queries (ask questions about the data) on GIS data, and produce customized map output.
How do Village of Gurnee Departments use GIS?