GeoJabber: Enabling Geo-Collaborative Visual Analysis

The GeoJabber concept, protocol, and working prototype software introduced here enable same-time, different-place collaborative geovisualization. The key problem this work addresses is how to turn geovisual software states into persistent textual representations that can be shared between users. In the current implementation, GeoJabber leverages three key Open Source technologies: the GeoViz Toolkit, the Jabber protocol, and XStream. GeoJabber is the first project to support same-time different-place geovisualization tool state sharing. As part of this effort, this paper presents a typology of sharable geovisualization software states, rooted in the concepts of data, display, and category.     

Spatial Accuracy Assessment of Wetland Permit Data

A collection of permits granted for alterations to coastal wetlands in North Carolina from 1984 through 1992 was examined to determine the spatial accuracy of the data. Each permit site for which a precise location existed in its associated permit file was surveyed using a Global Positioning System, and the error was identified between the location described in the permit file and the true location. The error was analyzed with respect to direction of error, accompanying map type, and time. Results suggest that the spatial error found in the Permit Record for coastal North Carolina was too large to perform spatial analysis. Only 50 percent of the permit sites were found within 250 meters of their true location, and the rest were in error by as much as 45 kilometers. Errors were uniformly distributed in direction and not biased in any direction. The inclusion of maps with greater detail did not significantly reduce error in locating the permit site. There was a slight decrease in error over time, but the fit was not sufficiently strong to indicate an improvement in accuracy over time. The results suggest a need for better standards for gathering future data and call for more stringent spatial data quality controls on environmental permit data of this kind.     

Developing Web-based Mapping Applications Through Distributed Object Technology

Emerging web-based mapping technologies use the World Wide Web (WWW) and Internet protocols to provide the ability to distribute, access, and visualize geospatial information over the Internet. Many web-based mapping applications have been developed to deliver geospatial information within and across organizations and even to the public at large. A major technological challenge is to achieve interoperability amongst web-based mapping applications so that mapping and geoprocessing resources distributed over the Internet can be shared and integrated. This paper presents an approach to the development of web-based mapping applications using distributed object technology in order to enable interoperability. Distributed object technology combines object technology, which utilizes reusable software components (called objects) that model real-world entities to build software systems, and distributed computing, which allows computing resources to be distributed and accessed over computer networks. The paper introduces a distributed object technology, the Common Object Request Broker Architecture (CORBA); proposes an architecture for web-based mapping using CORBA; and presents a prototype implementation.     

Maps and Mapping Technologies of the Persian Gulf War

Assessing the recent Persian Gulf War from a cartographic standpoint is now possible. Unlike in previous wars, which established new technologies for postwar cartographic exploitation, the gulf war is unique in having presented a proving ground for electronic cartographic technology. An analysis is given of map coverage of the war by the media, especially magazines and newspapers, and from a military perspective. From a cartographic standpoint, the winners in the war include hand-held Global Positioning System (GPS) technology, geographic information systems (GIS), workstation-based image processing and cartographic map-production systems, and radar imaging from aircraft. More fully exploiting and building on the success of these technologies in peacetime seems to be a clear mandate for academic and professional cartography.