Social Sciences, Statistics and Mapping Social Sciences, Statistics and Mapping
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A Geographic Information System (GIS) can be defined as a computerized database system for the capture, storage, retrieval, analysis and display of tabular and spatial data. GIS is used by many disciplines, including geography, urban planning, engineering, landscape architecture, environmental sciences and sociology. It provides individuals from varied disciplines with a set of tools to improve the efficiency and effectiveness of working with map information of spatial and non-graphic tabular attributes.
ArcIMS version 2, from ESRI, will soon be available at NYU, and version 3 is in the works. ITS Academic Computing Services has already installed this web software on a Social Sciences, Statistics and Mapping Group PC server. Soon, researchers will be able to design web-friendly map pages using ArcIMS, and insert links from their own web pages to these applications running on the Group server.
At the most elementary level, ArcIMS allows researchers to store maps and later display them within a digital archive accessed from a website. The maps are displayed independent of the hardware and may be resized without distortion of the fonts and geometry. This is possible because the maps are not stored as simple pictures. The features of the map--streets, lakes, identifying labels--are recognized by the software. A label is recognized as a label, so that if we zoom in and double the size of the map, the label does not become absurdly doubled in size. A line used for a road is a vector not a collection of pixels, and again, as we zoom in, the lines on the map will not increase in size. This functionality comes from ArcInfo, a powerful program which has been available at NYU for several years. What ArcIMS does is to make it possible to use ArcInfo functionality on the Web.
There are other applications of IMS that are more complex than the simple display of maps. In order to give you a feel for the usefulness of this new software, two projects will be detailed. They fall within two classes of GIS applications: computational and front-ends to databases.
Computational GIS applications involving spatial analysis have existed for a long time. One example would be a program that could calculate the shortest delivery route given ten addresses. ArcIMS makes it possible to run this type of application on the Internet.
The second class of applications, front-ends to databases, uses a map to connect to a database. We see this all the time when we browse the Web. We are shown a map and, using a mouse, we choose the geographical region we are interested in. A simple example of this is a web page of the campus where the user clicks on a building and information about that building is displayed. The U.S. Bureau of the Census uses this type of portal to facilitate the retrieval of data from their site (see "Front-End to Database" example below).
The problem at hand is to select a route for an oil or gas pipeline, in this case to connect two towns in the mountains of western South Dakota, an area for which a wealth of detailed data is freely available. This is a real-life land-use problem fraught with political snares, roadblocks, and pitfalls. Favoritism becomes an issue as land values are suddenly distorted near the route; economic development has to be weighed against damage to the environment, scenic devastation, and health concerns--the real issues are far-reaching and complex. Anyone from a concerned citizen to a government official to a utility engineer might be involved in such decisions and would be affected by the outcome. Ideally, a tool like this running on a web page will allow infrastructure to develop to the benefit of all.
The power of a modern GIS allows these computations to be calculated and recalculated almost instantly on a relatively inexpensive computer. The power of the Web takes this tool to another level, allowing these important political, economical and environmental decisions to be acted on quickly, perhaps in one evening at a virtual town meeting involving the different factions. At various convenient sites, concerned parties could suggest changes to the pipeline route and the information underlying the map would be used to immediately recalculate the cost of the pipeline. If consensus is possible, it could be recognized at that time; if not, at least everyone involved would know more about the options.
How do you effectively distribute data on 250 million people, 100 million households, and 15 million businesses to the users of that data? For the U.S. Bureau of the Census, the solution to that problem lies in making the census data available through the Internet.ArcIMS manages the Census retrieval application which allows the online display of maps to generate the data retrievals. But many other issues have to be managed as well. For instance, as with many information systems, the technical group is not responsible for the content. Corrections in maps and data are common occurrences in managing census data. This system must not only be open to citizens for retrieval but to the very large Census Bureau for editing. Many data retrieval applications are available for viewing at their website: www.esri.com/software/internetmaps/index.html. ArcIMS contains four applications: Author, Administrator, Designer, and Manager. Each of these can be used sequentially to quickly set up a website. Author creates an AXL fileArcs version of HTML that is used by Administrator to start a Map Service. Advanced functionality allows programmers to fully customize many aspects of IMS. Simple maps with standard interactive web features are much easier to create.In 1997, ESRI was part of a team chosen by the U.S. Bureau of the Census to help build the Data Access and Dissemination System (DADS), which will become the Internet site through which users of census data, from school children to state data centers to researchers of demographic data, will gain access to census data. This site has become known as the American Fact-Finder and is now available on the Internet at http://factfinder.census.gov.
ESRI is partnering with IBM, who is the prime contractor for this multi-year project, which will make census data widely accessible to internal and external users. Other participants in the project include Oracle Corporation, which is providing consulting and software development services in the deployment of the census data warehouse that will serve as the repository of all census data accessible through the site.
The
Social Science, Statistics and Mapping Group plans to make ArcIMS available to
the NYU research community by late February. Visit the software developers
(ESRI) map museum to view many interesting types of
IMS applications, and visit our website,
www.nyu.edu/its/socsci/GIS/, for a demonstration of the NYU implementation.
Contact Frank LoPresti (212-998-3398) for more information.
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Yekaterina Bolotnaya is a student aide in Frank's group and an undergraduate
Computer Science major.
yb258@nyu.edu
Posted February 16, 2001
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