Going Geo

By J.B. MilesSpecial to GCNWhen the National Cancer Institute wanted help assessing the relationship between environmental factors and breast cancer for the Long Island Breast Cancer Study Project, it asked AverStar Inc. of Burlington, Mass., to develop a prototype geographic information system to initiate the study.AverStar officials said the GIS will be the first system to provide data for the relationship between breast cancer and exposure to environmental hazards such as contaminated drinking water, air pollution, electromagnetic fields and radiation, pesticides and other toxic chemicals, and hazardous and municipal wastes.The project is just one example of the growing number of uses for systems that put data of all kinds into a geographic context.The Global Forest Watch program is using GIS software donated by Erdas Inc. to analyze satellite imagery and map the precise condition of forests in Russia, Canada, Venezuela, Chile and the United States to help identify threats such as logging, mining, road building and other forest development.Global Forest Watch was launched earlier this year by the World Resources Institute to map and publicly document forest development activities around the world.New England Electrical System companies are using a GIS to better manage their right-of-way corridors through the forests and townships of New England.The Kenerson Group, a Boston GIS consulting agency for public utility industries, developed the Vegetation Integrated Information Management Solution using the ArcView GIS from Environmental Systems Research Institute.'Transmission systems occupy sensitive habitat, adjoin or occupy areas owned by private citizens, and can interrupt or displace ecosystems,' said Kerri Kenerson, director of the Kenerson Group. The VIIMS system was designed to help the utility company maintain its right-of-way without impinging on these other concerns, she said.Both large- and small-scale projects can make use of a GIS. MapObjects, from ESRI, is used in conjunction with ShotSpotter from Trilon Technology LLC and Bradshaw Consulting Services Inc., and the Communicator from Dialogic Communications Inc. to help find ways to reduce illicit gunfire in urban areas.ShotSpotter first detects gunfire with specialized microphones strategically placed within high-crime areas. It then uses MapObjects to locate exactly where the shots were fired. MapObjects generates map and aerial photograph displays and provides law enforcement with the name, address and phone number of the home or business closest to the gunshot. The Communicator then uses this information to initiate a system of rapid notification to area residents.The use of GIS applications is expanding annually as industrial, economic, military and government planners learn to harness their benefits. Total GIS core business revenues worldwide'including software, hardware and services'reached $1.5 billion last year, up 10.6 percent from 1998, according to a study by Daratech Inc., a Cambridge, Mass., market research company.GIS software revenues alone accounted for $845 million, a 12.8 percent increase over 1998, the Daratech study disclosed.This guide lists desktop PC GIS programs that are compatible with Windows 95, 98 and NT operating systems, as well as Mac OS for the Macintosh and various flavors of Unix for such workstations as the Sun Microsystems Sparcstation series.Although there are relatively few, I selected them for their versatility. Most can easily be customized to meet goals as diverse as studying the effects of pesticides on wildlife in Michigan, finding the best site for an airport in Florida, or determining the amount of toxic waste oozing from a landfill into a swamp at the end of a street.Some vendors listed, notably industry leaders such as Caliper Corp., Caris Ltd., Erdas, ESRI and Intergraph Corp. provide entire suites of GIS modules targeted to specific industries or interest groups. The products are too numerous to list here. More information is available on the companies' Web sites.Other GIS software manufacturers market their products as part of service packages for a number of industry functions, such as oil and gas exploration, municipal planning or public utility operation. For a list of these and manufacturers of other GIS products, visit , an excellent online source of GIS news and developments worldwide.By definition, a GIS is a system designed to work with data referenced by spatial or geographic coordinates. GeoMicro Inc., a GIS software company, defines a GIS as a program that 'captures, stores, retrieves, analyzes and displays spatial data using a set of hardware, software and procedures.' A GIS combines the capabilities of databases with the visualization and geographic analysis offered by maps, according to a company white paper.A Geological Survey report on geographic information systems lists six basic functions that GIS programs should perform Check the USGS' Web site, at , for more details: If an Idaho farmer could relate information about the rainfall in his state to aerial photographs of the county where his potato farm was located, he might be able to gain information about optimum planting and harvesting times. By using a GIS, he could input information from many different sources and in many different forms for a solid analysis of the results.In any case, the primary requirement for the source data is that the GIS recognizes the locations of all variables, which are annotated by x, y or z coordinates of longitude, latitude and elevation, or by other systems such as ZIP codes or mile markers. Because any variable that can be found spatially can be digitized and fed into a GIS, it is possible to use various types of digital information such as satellite images and census data in the system. If data to be used by the GIS isn't already digitized, the program can use various techniques to capture it. For example, portions of maps can be digitized by drawing around them with a computer mouse or by using electronic scanners to convert map lines and points into digital data.Once a GIS has captured and digitized data, extraneous data can be edited out and the resulting information placed into a specialized database. A GIS can link information from various, usually incompatible sources by using combinations of mapped variables for building and analyzing new variables.The Geological Survey cites the example of researchers who combine data from a GIS and billing information from a water company to simulate the discharge of materials in the septic systems in a neighborhood upstream from a wetland. The water bills show how much water is used at each address, and the total amount of water used by the neighborhood helps predict the amount of material that will be discharged into the septic system. Thus, a GIS can identify neighborhoods with heavy amounts of septic discharge. Maps are designed according to different scales, but a GIS can adjust the scale of one map to fit another's. If the maps use different types of projection'a mathematical method of transferring information from the Earth's three-dimensional curved surface to two-dimensional paper or computer screen displays'the GIS can blend the projections into a common one using a PC or workstation. Digital data is collected and stored in many ways, so two data sources may not be compatible. A GIS can make them compatible by restructuring the data; that is, converting it to different formats. In this way, a regional property map may be related to a satellite image of the entire area. The Geological Survey cites such problems as the difficulties of relating wetlands maps to rainfall amounts recorded at several points, such as airports, TV stations and high schools. Because a GIS can depict two- and three-dimensional characteristics of the Earth's surface, subsurface and atmosphere from many information points, it can generate a map with rainfall contour lines that indicate rainfall amounts in specific locations.XXXSPLITXXX-