Introduction
A Geographic Information System (GIS) is an organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display many forms of geographically referenced information (ESRI, 1995). GIS has been widely used in solving a variety of planning problems. Together with the use of the Word Wide Web (WWW), GIS could be further developed to allow many more people to have access to GIS functionality and to enhance community participation in planning. Public participation is an approach in which public is brought to play an active role in planning process by its early stages. The major concern is to use GIS as a tool for communication between different interest groups like planners, decision makers and public.
The rapid growth of the Internet provide highly customized, accessible, and interactive source of public information and is changing the ways that people capture and manipulate spatial information. It is expected that the implementation of Web-based GIS could provide interactive mapping and spatial analysis capabilities for enhancing public participation and collaboration in decision-making processes. A public participation approach situates GIS analytical tools within an expanded framework of communication and discourse, opening opportunities for public participation (NCGIA, 1996). "Public Participation GIS" (PPGIS) is conceived broadly as an integrative and inclusive process-based set of methods and technologies amenable to public participation, multiple viewpoints, and diverse forms of information (Krygier, 1997a). Technological developments have made PPGIS possible only recently (Krygier, 1997b). Little is known about the technologies and theories that will enable such participatory activities. What role do the Internet and WWW play as effective media for public participation? What are the technical, practical, and theoretical issues raised in providing access to database and GIS tools relevant to particular decision problems? Moreover, as the need to expand the access to spatial information for participatory kinds of activity and personal use increases, more and more researchers are recognizing the need for a new kind of GIS (Nyerges and Barndt, 1997).
Web-Based GIS
The Internet and Web-based GIS is an effective medium for PPGIS. However, Web-based GIS is not a single technology. These technologies related Web-based GIS include Object-Oriented Language, GIS package and language, HTML, CGI, and the theories about PPGIS.
It is important to define the different forms of Web-based GIS, before selecting a appropriate for any given application. There are currently five forms of Web-based GIS applications (Pima County CAD/GIS, 1997):
- Graphic Snapshots of pre-generated maps
- Spatial Database Catalogs and Libraries
- Map Generators
- Real-time Map Browsers
- Real-time Maps and Images
Public Participation In GIS
Increased public involvement in the definition and analysis of questions tied to location and geography is the domain of Public Participation GIS (PPGIS). This approach facilitates the meaningful introduction of appropriate forms of spatial information and related technologies for widening public participation in the Policy making process (NCGIA 1996). This participant driven framework should be capable of representing diverse views without forcing premature resolution of contradictions, inconsistencies and disputed as they arise.
Contexts for introducing PPGIS would include community economic development, environmental dispute resolution, participatory planning, and other activities involving public collaboration. Technologies chosen or developed to support this approach can be designed to document and record the problem resolution process, allowing evolving priorities and problem definitions to be tracked by all participants. Sandman (1993) has identified nine publics relevant to discussion about community problems. The publics include: neighbors, concerned citizens, technical experts, media, activists, elected officials, business and industry, and local, state and federal government regulators (Nyerges and Barndt, 1997). A public participation approach would situate GIS analytical tools within an expanded framework of communication and discourse, opening opportunities for public participation across the processes of problem definition and problem resolution (NCGIA, 1996).
Recent discussions presented at the NCGIA Initiative 19 specialists' meeting (GIS and Society) and at the annual meeting of the Association of American Geographers have identified a set of questions concerning future development of the tools of spatial analysis in relation to their public context. Similar themes were addressed at NCGIA Initiative 17 (Collaborative Spatial Decision-Making). The discussions of PPGIS have been directed toward various of partial outcomes, such as the development of more user-friendly interfaces, network access to GIS, use of GIS as a communications medium, data creation based on local knowledge and sketch map capacity, public access to digital data archives, and the inclusion of groups often marginalized by the costs or expertise requirements of information technology (NCGIA, 1996).
State of the art Web-based GIS technology can play an important part in the development of PPGIS and Personal GIS (Nyerges and Barndt, 1997). Moreover, PPGIS and Personal GIS would be capable of managing and integrating all data components and participant contributions from one interface. Components would include e-mail, access to data archives, presentation of parallel texts and counter texts in diverse media, real-time data analysis, standard base maps and data sets, sketch map and field note capabilities (Schroeder, 1995).
The Methods of Web-Based GIS
How does Web-based GIS Work
There are many different products that can be used to implement Web-based GIS as described in section. They include MapGuide, MapObjects, ProServer, GeoMedia Web Map, Spatial WebBroker, APPIAN "Carta", Spatial Net and CARIS Internet Server.
Web-based GIS users can use a Web browser to navigate maps and do basic spatial analysis. A user enters specifications such as location, thematic layers, or searching requests on the web page to set up the environment for mapping or searching. Users can also click buttons to start display commands such as zoom in, zoom out, identify, pan, query, etc. The requests from user will be sent to clients by way of HTML forms. The form is passed to the web server. A gateway at the web server passes the request to a GIS server. For instance, the gateway could pass the request in the form of HTML to a MapObjects Internet Map Server. The MapObjects Internet Map Server (ESRI, 1996a) then generates a graphic file that will be converted to a GIF image or JPEG image. The GIF or JPEG image is later sent back to the client and viewed by the users with a standard web browser.
The basic series of steps is:
- Create the form.
- Pass the arguments to a script (CGI).