Database and Design Considerations for an Online Urban Atlas

The U.S. Bureau of the Census Urban Atlas project in the 1970s was an attempt to provide the public access to maps of selected census statistics. The technology of the time, however, only permitted a very limited number of census characteristics to be displayed in an atlas and at only one census geography—census tracts. The atlases also had limited availability and accessibility. Today the World Wide Web (the Web) provides a platform for an online version of the Urban Atlas concept that can be available to a global community for accessing the full release of census characteristics and geographies. This paper presents the system and database design and implementation of such an urban atlas for the state of Connecticut. Using a full database approach for both census statistics as well as geographic units, differing study areas, geographic units of display, and original or derived census variables, can be easily defined and mapped. The database platform also permits a future expansion of data services such as downloading as well as analytical services, including statistical analysis that may be of interest to the user community. online version of the Urban Atlas concept to be available to a global community that can access the full release of census characteristics and geographies. This paper discusses the design and implementation of such an urban atlas for the state of Connecticut. Web-based Map Dissemination The development of the Internet and the Web in the 1990s presented a new media for information dissemination allowing different methods for communicating map information. In the general model of cartographic communication, static maps are being replaced by interactive ones that allow the map user more control over how and what information is depicted (Peterson 1995) as well as multimedia presentations of that information (see Cartwright, Peterson, and Gartner 1999). All forms of mapping products are being redefined. For example, Slocum (1999) has defined an electronic atlas as “a collection of maps (and database) that is available in a digital environment. The more sophisticated electronic atlases enable users to take advantage of the digital environment through a variety of means, such as Internet access, data exploration, map animation, and multimedia. Electronic atlases may also permit users to create their own maps and analyze spatial data.” (Slocum 1999, 233.) Publishing these atlases and maps on the Web can take many forms. Kraak (2000) classifies maps published on the Web as being either static or dynamic. Static maps are bitmap images that are primarily used for display but that also can be used as a spatial index interface to other information (Kraak 2000). Dynamic maps are animations of spatial processes that also can be used in a view only environment or in an interactive one. Static maps typically are viewed by a Web browser using HTML tags, and can be used as a spatial index using the coordinates of polygons to define a “clickable region” (Kobben 2000).