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The computerization of maps has addressed many of the serious shortcomings associated with paper maps. The new field of geographic information management (GIM) has emerged from this effort. GIM focuses on 2 areas: 1. policy, which includes such issues as assessment, design, and planning, and 2. technology, which includes geographic information systems (GIS), computer-aided design, computer-aided mapping, and automated mapping and facilities management. A GIS, which is a computer system designed to collect, store, retrieve, manipulate, and display spatial data, includes a graphics workstation, a mouse, a digitizing tablet, a plotter, possibly a multigigabyte storage device, and GIS software. GIS combines aspects of hypertext-hypermedia and database management software in a unique and highly useful form. Currently available GIS packages include: 1. Atlas GIS for DOS from Strategic Mapping Inc., and 2. Tactician for Macintosh from Tactics International.
INTRODUCTION
As much as 80% of all information held by business and government may be geographically referenced(1). Examples include census data; mailing addresses; facility layouts; telephone numbers; land use information; and details about area networks such as water, electric, gas, sewer, cable, transportation, and telephone systems. Geographically-referenced information literally surrounds us.
Traditionally, paper maps have been used to represent geographically-referenced information. Paper maps, however, have several shortcomings. They are difficult to update, manipulate, and combine with other data.
The computerization of maps has addressed these and other shortcomings. As a result, not only has the usability of geographically-referenced information greatly improved but a new field has emerged: Geographic Information Management (GIM).
Geographic Information Management has two areas of focus: policy and technology. Policy issues include assessment, design, planning, and cooperation among users of geographic information. Technologies include Geographic Information Systems (GIS), Computer-Aided Design (CAD), Computer-Aided Mapping (CAM), and Automated Mapping and Facilities Management (AM/FM). Of particular interest here is Geographic Information System technology. This article provides an overview of GIS technology, its history, the software market, and general issues.
A GIS is a computer system designed to collect, store, retrieve, manipulate, and display spatial data. A typical system includes a graphics workstation, a mouse, a digitizing tablet, a plotter, possibly a multigigabyte storage device, and GIS software. Geographic Information Systems represent a new category of software and an excellent, practical application of hypertext/hypermedia. That is, most GIS software uses map regions and symbols to hide detailed information that can be revealed at the touch of a button.
A BRIEF HISTORY OF GIS
The origin of GIS may be traced back to the work of Roger Tomlinson in the early 1960s. Tomlinson and a team of coworkers developed the Canada Geographic Information System (CGIS) as part of a government project to inventory natural resources in the southern third of Canada. The maps produced by the system were used to rehabilitate marginal farmland and manage timber production. The CGIS is now a permanent, continent-wide system used for a variety of applications(2).
SYMAP, a raster-based computer mapping package, was another important system developed during the 1960s. Created by Harvard University's Laboratory for Computer Graphics and Spatial Analysis, SYMAP was unusual in its general-purpose design and low cost. Eventually over 500 institutions in the U.S. and other countries purchased copies of SYMAP. It served as a model for at least fourteen systems and indirectly contributed to a host of others(3).
In 1969, a former assistant at the Harvard Lab, Jack Dangermond, founded the Environmental Systems Research Institute (ESRI) in Redlands, California. ESRI's first product was GRID, another raster-based system. It was ESRI's primary software product until the 1980s(4).
Continued innovation at the Harvard Lab in the 1970s produced such systems such as POLYVRT, GEOGRAF, and ODYSSEY. One individual in particular, Nicholas Chrisman, played a key role in all three projects. POLYVRT extended the DIME file format developed by the U.S. Bureau of the Census, one of the few standards of the time. GEOGRAF was an early geographic data management system.
The Lab's most important project in the 1970s, however, was ODYSSEY. Up to this point, vector-based software for polygon overlays could not work with large amounts of data. ODYSSEY solved this by using a dynamic data structure in which a local processor computed the polygon overlays. The move from a raster to a vector-based approach allowed GIS to become fully integrated with other computer applications such as database management(3).
A co-developer of ODYSSEY, Scott Morehouse, joined ESRI in the early 1980s. Morehouse's experience at the Harvard Lab helped him become the lead designer of ESRI's ARC/INFO, the successor to GRID and PIOS(3). ARC/INFO is primarily a vector-based system and is discussed in the next section.
GIS SOFTWARE TODAY
The GIS market is divided into software for workstations and personal computers. Different companies supply software for the two hardware platforms but eventually a unified market should emerge. The size of the application determines the hardware needed but even small geographic information systems are demanding.
GIS SOFTWARE FOR WORKSTATIONS
There are three major vendors that dominate the high end of the GIS market(5). These are ESRI, Intergraph, and ERDAS(Table 1). The leading workstation product is ESRI's ARC/INFO with about an eighteen to twenty percent market share. Part of ARC/INFO's success is due to ESRI's willingness to support a wide variety of data formats and hardware platforms. Supported data formats include DIME, DLG, ETAK, and TIGER. Hardware platforms include Apollo, Hewlett-Packard, Sun, and VAX systems.
ARC/INFO is a combination of two products. ARC processes cartographic data using a vector-based approach and INFO adds a relational database management system. Several modules are available to let ARC/INFO process raster, elevation, and other types of data.
TABLE 1
CONTACT INFORMATION FOR THE THREE MAJOR GIS SOFTWARE WORKSTATION VENDORS
ARC/INFO ESRI Systems, Inc. 380 New York Street Redlands, CA 92373 714/793-2853
ERDAS ERDAS, Inc. 2801 Buford Highway, NE Atlanta, GA 30329 404/248-9000
INTERGRAPH Intergraph corporation One Madison Industrial Park Huntsville, AL 35807 800/826-3515
TABLE 2
CONTACT AND PRICING INFORMATION FOR IBM GIS SOFTWARE
Caliper Corp. 1172 Beacon St. Newton, MA 02161 617/527-4700 PRODUCT: GisPlus--$2,995
MapInfo Corp. 200 Broadway Troy, NY 12180 800/327-8627 PRODUCTS: MapInfo--995 MapInfo for Windows--$995
Strategic Mapping, Inc. 4030 Moorpark Ave. Suite 250 San Jose, CA 95117 408/985-7400 PRODUCTS: Atlas GIS--$2,495 Atlas Pro (DOS)--$795 Atlas Mapmaker for Windows--$495 Import/Export--$495 Atlas Script--$495
TActics International 16 Haverhill St. Third Floor Andover, MA 01810 800/927-7666 PRODUCT: Tactician--$2,495
Intergraph is ESRI's fiercest competitor in the evolving GIS marketplace. The major difference between the two companies is that Intergraph markets turnkey systems for various GIS applications. These include general purpose as well as stereodigitizing workstations for direct input of data. Intergraph software is also vector-based like ARC/INFO and connects with add-on packages that process raster, elevation, and other types of data.
ERDAS Inc. markets the Earth Resources Data Analysis System (ERDAS), which is based in part on the IMGRID software developed at the Harvard Lab(3). Unlike ARC/INFO and Intergraph, ERDAS is primarily a raster-based system. This approach is especially useful for applications such as natural resources management and military intelligence that use remotely-sensed (satellite) data.
TABLE 3
CONTACT AND PRICING INFORMATION FOR MACINTOSH GIS SOFTWARE
PC Globe, Inc. 4700 South Mcclintock Tempe, AZ 85282 800/336-6314 PRODUCT: Descartes--$395
GeoQuery Corp. 475 Alexis R. Shuman Blvd. Suite 380E Naperville, IL 60563 800/541-0181 PRODUCT: GeoQuery--$395
MapInfo Corp. 200 Broadway Troy, NY 12180 800/327-8726 PRODUCT: MapInfo for Macintosh--$995
Strategic Mapping, Inc. 4030 Moorpark Ave. Suite 250 San Jose, CA 95117 408/985-7400 PRODUCTS: Atlas Pro (Mac)--$795 Atlas Mapmaker--$495
Tactics International 16 Haverhill St. Third Floor Andover, MA 01810 800/927-7666 PRODUCT: Tactician--$2,495
John Wiley & Sons, Inc. 605 third Avenue New York, NY 10158 212/850-6222 PRODUCT: MAP II--$99
GIS SOFTWARE FOR PCs
In the past few years a number of GIS software packages for personal computers have appeared. See Table 2 for a list of IBM software and Table 3 for a list of Macintosh software. Atlas GIS for the IBM and Tactician for the Macintosh were selected as representative of some of the best GIS software available for personal computers and reviewed.
ATLAS GIS FOR DOS
Atlas GIS is a general-purpose, vector-based Geographic Information System marketed by Strategic Mapping, Inc. The firm's other products include Atlas Pro (for DOS and the Macintosh) and Atlas MapMaker (for Windows 3.0 and the Macintosh). Atlas GIS is the most sophisticated of these. Table 4 lists system requirements.
MAP CONSTRUCTION
Atlas GIS uses three primary file types: geographic, attribute, and datapoint. Geographic files contain locational data for each map feature (region, line, and point). A map layer can contain only one feature at a time but up to 250 layers may be combined in a single map. The attribute and datapoint files are dBASE III PLUS compatible, which is useful for importing existing databases. Attribute files hold information about region and line features while datapoint files contain information about points. For example, an attribute file for a region may hold ownership and zoning information. A datapoint file, on the other hand, may contain customer, store, or other information.
MAP ANALYSIS
The capabilities of Atlas GIS indicate that Strategic Mapping has been successful in porting many mainframe features to the desktop. Once a map has been created, the system allows several types of queries: by map feature, by relations among features, and by relations among attributes. Let's look at each of these in turn.
TABLE 4
MINIMUM SYSTEM REQUIREMENTS FOR ATLAS GIS
IBM XY 640K RAM EGA Monitor 10 Megabytes of Hard Disk Space MS-DOS 3.0 or later
To select by map feature, the user must first select the layer or set of layers with which to work. Then, the cursor keys are used to identify the feature and the <enter> key selects it. Atlas GIS indicates the feature has been selected by highlighting it. Further information on the feature can then be pulled up.
Relationships among map features may be displayed by first selecting the layer or set of layers desired and then using the functions "inside," "touching," and "near." The Select-Geographic-Inside function can be used to find all customers within a zip code, for example. The Select-Geographic-Touching function can help find such things as the cities on the banks of a river. Finally, the Select-Geographic-Near function can be used to find all libraries within a fifty mile radius of a corporation.
Attribute queries are similar to those performed on traditional relational databases with the exception that the results can be displayed geographically. For example, instead of just creating a report showing all customer sites with more than $100,000 in sales, Atlas GIS can show these sites on a map. Once the sites are displayed, summary statistics are also available. These include count, sum, average, minimum, and maximum.
MAP PRESENTATION
Atlas GIS also gives the user the ability to create several types of thematic presentation maps. These are ranged maps, proportional maps, and dot-density maps. Ranged maps show data in ranks represented by color, symbol, fill pattern, and so on. Proportional maps are modified ranged maps. That is, they show data by varying the percentage of fill pattern or symbol in direct proportion to the underlying data value. Dot-density maps fill regions with dots that are uniform in size and randomly placed. The density of the dots is proportional to the underlying data value.
TABLE 5
CENSUS BUREAU ORDERING INFORMATION
UNITED STATES DEPARTMENT OF COMMERCE
Bureau of the Census Data User Services Division Customer Services Branch Washington, DC 20233-0001 301/763-4100
ATLAS GIS OPTIONS
The basic Atlas GIS package includes a number of bundled geographic data sets: all countries and 1500 major cities of the world; U.S. states, counties, major cities, interstate highways; 5-digit zip code centroids; U.S. telephone area codes; and MSA, ADI, and DMA boundaries. The company also sells an extensive line of supplemental map and statistical databases, such as business locations, retail trade, health services, yellow pages data and others.
An important add-on product is the $495 Atlas Import/Export module. It allows Atlas GIS to work with TIGER, DIME, ETAK, and other data formats. The use of the Import/Export module to convert TIGER files is stressed here because the U.S. Census Bureau's TIGER files (the basis for the 1990 Census) are relatively inexpensive and can be used to build sophisticated GIS applications. TIGER files for every state in the country may be purchased from the Census Bureau in CD-ROM format. See Table 5 for ordering information. Preprocessed TIGER files are also available from SMI.
USING ATLAS GIS
While Atlas GIS came with files for Ohio it was decided that importing some CD-ROM TIGER files would better test the capabilities of the software. Using a 6 MHz IBM AT (i.e., a relatively slow machine) with a 40 megabyte hard disk and an EGA monitor, it took approximately 11 hours to convert all TIGER files pertaining to Allen County, Ohio from the CD-ROM to Atlas' format. Allen County covers an area of 405 square miles, has a population of 112,000 and contains one city, Lima.
The Atlas file set for Allen County was about 2.5 megabytes in size. To plot a map based on the data, the computer had to calculate all vectors for this county and display them. This took about twenty minutes at the default scale of 1:241,734. The digital map detailed all boundaries, streets, railroads, and provided symbols for a number of geographic features such as reservoirs and lakes.
Once the map is set up in Atlas GIS, operations are relatively quick. For example, a change in scale to one-fourth the original (1:60433.5) took only a few minutes to redraw. Selecting a geographic feature is simply a matter of using the cursor and <enter> keys. Once a feature is selected, the system can give you detailed information about it. In this case, the database contained only the name of the feature and its geographic coordinates (e.g., Twin Lake Reservoir at a Longitude of 84 degrees, 5 minutes, and 5.19 seconds West and a Latitude of 40 degrees, 44 minutes, and 40.75 seconds North).
Experience in using Atlas GIS with TIGER files indicates that four hardware factors are critical: speed, storage, display size and resolution. While the test machine met the minimum requirements, it is strongly recommended that users run Atlas GIS on a 386 or 486 system with a Super VGA display and several hundred megabytes of hard disk storage. Besides being very slow, a major drawback to the test system was that the EGA display could not make some of the screen information legible. Atlas GIS was also briefly tested on a CompuAdd 386 with a VGA display and this did help but some screen items were still hard to read.
ATLAS SCRIPT
At press time, Strategic Mapping, Inc. announced a new $495 product, Atlas Script. According to Steve Poizner, president of SMI, Atlas Script is similar to dBASE and has 125 commands. These commands can be used to create menus and forms, display information in pop-up windows, develop macros, and draw objects on the screen. Atlas Script will help GIS designers customize their applications for decision makers and other end-users.
TACTICIAN FOR MACINTOSH
Tactics International has developed Tactician, another vector-based system, with an eye on business applications. See Table 6 for system requirements. Tactician is specifically designed for sales and marketing applications, such as retail site location analysis, promotion planning, direct mail analysis, and sales territory management.
Like Atlas GIS, Tactician stores map information separately from user data. The user data is stored in a proprietary spreadsheet format where rows are geocodes and columns are user-defined variables. A geocode is a twelve character identifier that links the spreadsheet data to the map. The variables are any values that can be geographically referenced (e.g., income, age, and sales).
The spreadsheet can either be two-or three-dimensional. The two-dimensional mode is for a standard Tactician document with rows of geocodes and user-defined columns. The three-dimensional mode is for a sites or territories mode document. The third dimension is a detail sheet selected from a summary sheet for that site or territory.
A few words should be said about Tactician's three data modes. Standard mode allows data to be mapped. The two other modes provide special tools. Sites mode helps manage and analyze retail trade areas. Territories mode assists in territory balancing and sales management.
MAP CONSTRUCTION
In Tactician, the basic map building block is called the layer. Layers are made of geographic features such as points, lines, polygonal areas, polygonal areas made of line segments, sites, and streets. Like Atlas GIS, all the data in a layer must be of the same type.
Overlays are descriptions of how to display the map layers. For example, a state overlay may tell Tactician to display state borders in blue and state interiors in white. Some standard overlays supplied with Tactician are cities, highways, malls, states, and zip codes.
There is an important interaction between map scale and display of overlays. A map can be designed so that certain overlays appear only at certain scales. For example, a map of the United States can display state boundaries at a large scale and hide county boundaries. At a smaller scale, state boundaries disappear and county boundaries are revealed. This design feature is useful in hiding the complexity of the geographic information contained in a database.
One of Tactician's features deserves special mention. It has a built-in utility to import foreign cartographic files. With Atlas GIS this option does not come with the basic package but costs an additional $495. In any case, Tactician's import feature will convert Atlas, DIME, ETAK, MAPINFO, SDS NTDB, and TIGER files.
TABLE 6
SYSTEM REQUIREMENTS FOR TACTICIAN
Macintosh II 4 Megabytes of RAM Color Monitor 20 Megabytes of Hard Disk Space System 6.0.5
MAP ANALYSIS
Tactician is designed to tap into large corporate databases using CL/1 and an Ethernet connection. This allows existing data to be incorporated easily and quickly. The external database must have something that can act as a geographic reference, such as a zip code field, in order to be integrated into a Tactician map.
Once the data is incorporated into a map, Tactician allows queries through its Snooper/Query Tool. A single click on the Snooper Tool icon activates it and changes the cursor to a magnifying glass, which can be used to find out information about any geographic feature on the map. A double click on the Snooper Tool icon brings up the Query Tool Parameters dialog box. This allows the user to limit the search to a particular map overlay.
The Snooper/Query Tool can also be used to point at features on the map and create subsets of the underlying spreadsheet data. Spreadsheet data can either be copied among features in the existing document or added to a new Tactician document. The spreadsheet approach used by the program takes some getting used to but is well worth the effort.
MAP PRESENTATION
Tactician offers a number of presentation options. These include ranged and dot density maps. In addition, users can enhance maps with bar charts, pie charts, sector charts, and colors before printing.
TACTICIAN OPTIONS
Similar to Atlas GIS, Tactician comes with a number of basic data files. These include zip codes, counties, states, and interstate highways. Tactics International also provides a CD-ROM product, which contains 147 megabytes of high-resolution U.S. zip codes and other data. Tactics International supplied the CD-ROM files and the most current version of Tactician for this review.
USING TACTICIAN
Tactician was also tested with the CD-ROM TIGER files for Allen County, Ohio. During the conversion from TIGER to Tactician format more than 10,000 errors were generated. The resulting line files could not be opened. According to Tactics International, the TIGER files must first be stripped of all line feeds in order to import them correctly. Unfortunately, the original documentation supplied with Tactician did not make this clear and the real problem was uncovered too late to test the conversion process.
At the time this review was being written, the documentation for Tactician was undergoing a major revision. The new manual arrived too late to avoid the problem discussed above but would have been a tremendous aid. It is a substantial improvement over the old manual in terms of clarity, organization, and indexing.
Documentation problems aside, Tactician performed well with the supplied demonstration files. These are covered in a Quickstart section of the new manual. In particular, Tactician's ability to reveal detail or hide it depending on the map scale is exceptional. The program provides two different ways to set the map scale. The first is Set Height (the distance between the top of the map and the bottom), which can be anywhere from 0.01 to 9999 miles. The second is a Zoom In/Zoom Out feature that allow the user to set a zoom factor and direction.
Tactician's navigational tools are also outstanding. For example, the user can jump from any location in the United States to a specific address in the database. Tactician then redraws the map centered on the new location. The Jump To option also works with only partial address information such as a zip code or a place name.
TACTICIAN FOR WINDOWS
As this article went to press, we heard that Tactics International had released a Windows 3 version of Tactician. The product is identical to the Macintosh version in functionality and appearance. Documents, maps, and data structures created with one version can be used with the other. In fact, the products are so similar that users receive the same Tutorial and User's Guide. Tactics International considers both the Macintosh and Windows 3 vital to its success in the GIS market.
MAJOR GIS ISSUES
The widespread use of GIS is limited by a number of factors. Three major ones are hardware, ease of use, and data limitations. Let's look at each of these in turn.
Desktop GIS use requires an expensive setup: a high resolution monitor, substantial processing power, and immense storage. Ongoing competition and technological innovation in the workstation and personal computer markets should bring GIS hardware into the price range of virtually everyone who needs it within two to three years. The trend toward more widespread use is evident in the role CD-ROM is playing in the distribution of GIS databases. The U.S. Bureau of the Census now routinely sends data out on CD-ROM (Table 5).
Tremendous strides have been made in ease of use but more work remains to be done. Most GIS applications require custom designed systems built on top of ARC/INFO or Intergraph software. One development eagerly awaited by GIS specialists is the release of more user-friendly software such as ArcView from ESRI, which will let users design some basic applications. ArcView provides many capabilities of a traditional GIS but adds an advanced graphical user interface. Its features include raster/vector display, user-defined map legends, spreadsheet tools, point and click feature selection, statistical tools, and extensive plotter/printer support. The product is designed to run on UNIX workstations, IBM personal computers, and the Macintosh. And, as you would expect, it reads ARC/INFO databases but has limited analysis and manipulation capabilities.
Assuming cost and ease of use problems improve, the concerns about data will remain for some time. At present, the vast majority of organizations owning geographically-referenced information do not adhere to existing data format standards. The U.S. government's efforts with the TIGER and DLG formats are important steps in the right direction but the needs of both government and business will require the development of additional standards. At the federal level, standards coordination is done by the Federal Geographic Data Committee. For information about statewide efforts see the Council of State Governments' State Geographic Information Activities Compendium.
In addition to standards, the quality and limitations of data are important concerns. A group of vendors has emerged that sell products just to correct and enhance federal GIS data. State and corporate data share many of the same quality problems. Also, potential GIS users often face limitations on what high quality data they do own. For example, a state wanting to develop a GIS database on water resources may find that it has only partial data with which to work because there has been no coordinated effort to perform a statewide inventory. Though the projected benefits are great, the substantial cost of collecting the missing data must also be considered.
THE FUTURE OF GIS
The projected growth rate for GIS is a minimum of twenty-five to forty percent per year for the remainder of the 1990s. This means the number of users will move from tens of thousands to hundreds of thousands and perhaps millions by the end of the decade. While these figures may seem overly optimistic, there are a number of good reasons to believe them.
First, government can become a more efficient and better manager by investing in a GIS. Administrative units that would clearly benefit include departments of commerce, environmental protection, agriculture, and natural resources; public utilities commissions; school districts; and agencies serving rural areas. In addition, certain large-scale problems, such as the refurbishment of the national highway system, cannot be solved without the aid of GIS technology.
Second, every medium to large business can benefit from CIS technology. Media advertisers can make use of ADI data to target new products and services at specific populations. Sales and marketing organizations can use GIS to balance territories, plan new stores, and analyze product promotions. The economic value of geographic data, especially census information, may make a critical difference in the survival and growth of many companies.
Third, some Geographic Information Systems are evolving into spatial information systems with major scientific applications. Areas such as astronomy, ecology, and medicine will benefit from techniques pioneered by GIS. In astronomy, spatial simulations of quasars, black holes, and other phenomena may lead to important breakthroughs in understanding the universe. In ecology, environmental mapping will provide us with a far better knowledge of our ties to the Earth. Finally, modeling of proteins and other molecules may help create new medicines and further our understanding of many diseases such as AIDS(6).
SUMMARY AND CONCLUSION
A Geographic Information System (GIS) is a new and important tool for information management. This technology combines aspects of hypertext/hypermedia and database management software in a unique and highly useful form. Two examples of GIS software for personal computers are Atlas GIS and Tactician. Atlas GIS is a general purpose package while Tactician is designed specifically for business uses. Together, they represent the state-of-the-art in personal computing and GIS but they are not the last word. A number of new products with even more powerful capabilities will appear in the near future.
GIS technology, however, is not without its problems. Concerns center on hardware, ease of use, and data limitations. The latter is perhaps the most problematic. A GIS is only as good as its data and high quality data is expensive to collect and keep current. Therefore, GIS projects must be carefully planned and executed to get the best return on an often sizable investment.
With geographically-referenced information accounting for as much as 80% of all information held by government and business, GIS will have a tremendous impact on many aspects of our lives from health to transportation. The value of GIS technology is readily acknowledged by the federal and many state governments, which are spending several hundred million dollars annually on GIS applications. Business users are also beginning to invest, especially in applications based on 1990 Census data.' As a result, growth rates for GIS are expected to be in the range of 25 to 40 percent annually for the rest of the
Information specialists unfamiliar with GIS may want to explore potential applications in their organizational settings. Not all organizations can profit from harnessing geographic-referenced information but those that can should make the most of it with a GIS.
GLOSSARY
AREAS OF DOMINANT INFLUENCE (ADI) These are television viewing areas as defined by Arbitron.
CENTROID This is the center of a polygon.
DESIGNATED MARKET AREAS (DMA) These are television viewing areas as defined by A.C. Nielsen.
DIME FORMAT This is the predecessor to the U.S. Bureau of the Census' TIGER format. DIME was used for the 1980 Census.
DLG FORMAT The Digital Line Graph data file format was developed by the U.S. Geological Survey. These maps are at scales of 1:2,000,000; 1:100,000; and 1:24,000. DLG maps are the basis for ETAK street maps.
DOT-DENSITY MAP This is a type of thematic map in which areas are filled with dots that are uniform in size, randomly spaced, and in proportion to the data being represented.
ETAK FORMAT This is a data file format developed by ETAK Corporation to represent street information.
FIPS CODE The Federal Information Processing Standards Code was developed by the National Bureau of Standards to represent named geographic areas such as states and counties in computerized data files.
GEOGRAPHIC INFORMATION MANAGEMENT (GIM) This field is concerned with practical applications of geographic information technologies, such as geographic information systems, computer-aided mapping, and facilities management.
GEOGRAPHIC INFORMATION SYSTEM (GIS) A GIS is a combination of computer hardware and software designed to collect, store, retrieve, manipulate, and display spatial information.
GEOGRAPHICALLY-REFERENCED INFORMATION This refers to information tied to coordinates above, on, or within the Earth. Examples include census data, telephone numbers, and addresses. It is a subset of Spatial Information.
MAP This is an abstraction of physical space using a certain projection, scale, and symbology.
METROPOLITAN STATISTICAL AREA (MSA) This is a standardized area defined by the U.S. Bureau of the Census that contains at least 50,000 inhabitants.
PROPORTIONAL MAP This is a type of thematic map in which the percentage of the symbol or fill pattern varies in direct proportion to the geographic feature's underlying data value.
RANGED MAP This is a type of thematic map in which the data value behind each geographic feature falls within a certain rank. Ranks are represented by color, symbol, or fill pattern.
RASTER APPROACH This approach divides a geographic area into a series of grid cells, which are usually square. This approach makes it difficult to retrieve information about specific linear features. Remotely sensed (satellite) data are processed using this approach.
SDS NTDB FORMAT This is a data file format used by Spatial Data Sciences based on the National Transportation Database format.
SPATIAL INFORMATION This refers to object descriptions or measurements in three dimensions.
THEMATIC MAP This is a map in which variations among geographic data are represented by special graphics. Examples include dot-density, proportional, and ranged maps.
TIGER FORMAT The Topologically Integrated Geographic Encoding and Referencing computerized file format was developed by the U.S. Bureau of the Census for use in compiling the 1990 Census of Population.
VECTOR APPROACH This approach uses of a series of X,Y coordinates to describe point, line, and area (polygon) features. Examples include TIGER and DLG.
REFERENCES (1) OGRIP. Advisory Committee's First Year Report. Columbus, OH: Department of Administrative Services, State of Ohio, 1990.
(2) Tomlinson, R.F. "The Impact of the Transition from Analogue To Digital Cartographic Representation." The American Cartographer 15, No. 3 (1988): pp. 249-262.
(3) Chrisman, Nicholas. "The Risks of Software Innovation: A Case Study of the Harvard Lab." The American Cartographer 15, No. 3 (1988): pp. 291-300.
(4) Dangermond, Jack and Lowell Kent Smith. "Geographic Information Systems and the Revolution in Cartography: The Nature of the Role Played by a Commercial Organization." The American Cartographer 15, No. 3 (1988): pp. 301-310.
(5) Monmonier, Mark. "Geographic Information Systems." In: C.R. Perkins and R.B. Parry (editors), Information Sources in Cartography (pp. 214-231). London: Bowker-Saur, 1990.
(6) Lander, Eric S., Robert Langridge, and Damian M. Saccocio. "Computing in Molecular Biology: Mapping and Interpreting Biological Information." Computer 24, No. 11 (1991): pp. 6-13.
THE AUTHOR
CARL FRANKLIN is an assistant professor at the Kent State University School of Library and Information Science. He is also the coauthor of two books on information technology and a consultant. He writes frequently for DATABASE.
Communications to the author should be addressed to Dr. Carl Franklin, 124 Mount Hall, 1050 Carmack Road, Columbus, OH 43210; 614/292-7746.
Copyright Online, Incorporated Apr 1992