CaGIS vol. 30, no. 3

Editorial

1. Lynn Usery, University of Georgia & U.S. Geological Survey

As I begin my tenure as Editor of Cartography and Geographic Information Science (CaGIS), significant changes in the American Congress on Surveying and Mapping (ACSM) and in the journal CaGIS are occurring. The changes include a reorganization and restructuring of ACSM, digital publishing, and international recognition for the journal.

The membership of the ACSM has voted to make each of the member organizations an independent society with its own individual members. The member organizations-the American Association of Geodetic Scientists (AAGS), the Cartography and Geographic Information Society (CaGIS), the Geographic and Land Information Society (GLIS), and the National Society of Professional Surveyors (NSPS)-will each be a part of the Congress that forms ACSM and will continue to share mutually beneficial activities, such as the Annual Convention. The restructuring of ACSM takes effect on January 1, 2004. The resulting new organization and other changes underway have significant impacts on the journal CaGIS.

With the new structure of ACSM, CaGIS changes from the journal of the American Congress on Surveying and Mapping to the official journal of the Cartography and Geographic Information Society. Under the new organization, the society CaGIS and its individual members assume complete control of the journal, including the costs of publication and distribution and the revenue generated from subscriptions.

The journal CaGIS also has several other major changes that are benefits to the membership of the Society and to journal subscribers. Under the leadership of Terry Slocum, the previous CaGIS editor, the journal began digital publishing with the January 2003 issue. All future issues will be available in both printed and digital online form. The online version is completely text-searchable, providing an excellent service to CaGIS readers. The CaGIS Board of Directors has also authorized conversion of all back issues of CaGIS and The American Cartographer to digital, text-searchable form. While this process will require several years to accomplish, the digital archive of CaGIS will be a valuable resource to the membership.

The International Cartographic Association (ICA) has voted to make CaGIS one of the official journals of the ICA. This status, to be reflected on the journal cover, provides for CaGIS to include manuscripts from ICA and will require CaGIS to develop an international editorial and review process. The final editorial control of CaGIS remains with the current editor and editorial board, but manuscript submission and the content of CaGIS should be greatly enriched by increased international submissions and participation in the review process.

It is a time of exciting change as I assume the editorial responsibilities for the journal. These changes are occurring as a result of the excellent leadership and editorial capability provided by Terry Slocum. I take this opportunity to thank Terry for his stewardship of the journal and for making it a better asset to the readers. His careful guidance has led CaGIS to digital online publication, international status, and maintained the scientific quality that is the measure of a good academic journal. I hope to maintain his high standards and help make CaGIS a better resource for its readers.

Choosing Geographic Units for Choropleth Rate Maps, with an Emphasis on Public Health Applications

Francis P. Boscoe and Linda W. Pickle

Choropleth maps are the most widely used map type for mapping rates, such as those involving disease, crime, and socioeconomic indicators. The essential step of choosing a geographic unit to map is often made in an ad hoc manner. Among the desirable characteristics of choropleth mapping units are high degree of resolution, homogeneity of population size, homogeneity of land area, observation of minimum population thresholds and land area thresholds, temporal stability and currency, compactness of shape, audience familiarity, data availability, and the functional relevance of the unit to the phenomena mapped. Because of the uneven distribution of human populations, no single geographic unit can meet all of these characteristics in practice, and a well designed choropleth map necessarily involves some compromise. We present guidelines for choosing geographic units that take into account the above criteria, considering 12 geographic units ranging from census blocks to states. Even allowing for differences in scale and purpose, some units confer clear advantages over others.

KEYWORDS: Choropleth maps, disease rates, areal units

Testing Popular Visualization Techniques for Representing Model Uncertainty

Jeroen C.J.H. Aerts, Keith C. Clarke, and Alex D. Keuper

Many land allocation issues, such as land-use planning, require input from extensive spatial databases and involve complex decision-making. Spatial decision support systems (SDSS) are designed to make these issues more transparent and to support the design and evaluation of land allocation alternatives.In this paper we analyze techniques for visualizing uncertainty of an urban growth model called SLEUTH, which is designed to aid decision-makers in the field of urban planning and fits into the computational framework of an SDSS. Two simple visualization techniques for portraying uncertainty-static comparison and toggling-are applied to SLEUTH results and rendered with different background information and color schemes. In order to evaluate the effectiveness of the two visualization techniques, a web-based survey was developed showing the visualizations along with questions about the usefulness of the two techniques. The web survey proved to be quickly accessible and easy to understand by the participants. Participants in the survey were mainly recruited among planners and decision-makers. They acknowledged the usefulness of portraying uncertainty for decision-making purposes. They slightly favored the static comparison technique over toggling. Both visualization techniques were applied to an urban growth case study for the greater Santa Barbara area in California, USA.

Using an Energy Minimization Technique for Polygon Generalization

Martin Galanda and Robert Weibel

Snakes are iterative energy-minimizing splines controlled by both internal constraint forces (internal energy) and external forces (external energy). This paper investigates the use of snakes for the resolution of conflicts in polygonal subdivisions (i.e., polygon maps or polygon mosaics) resulting from the violation of metric constraints which exist if a polygonal object is too small, too narrow, or too close to another polygon. Such metric conflicts are denoted as size and proximity conflicts. In the generalization of polygonal subdivisions, internal energy reflects the resistance of an object to deformation and external energy describes the need for generalization. This paper suggests the usage of a snakes-based algorithm which is triggered in such a way that it achieves the translation, a local and global increase (or decrease) of polygons, or an arbitrary combination of these transformations, depending on the conflicts encountered. Hence, size and proximity conflicts within a group of polygons can be solved simultaneously and holistically. Furthermore, snakes support the propagation of a change of a polygon’s geometry to all adjacent neighbors. The proposed algorithm has been implemented in a prototype system that also supports a variety of other polygon generalization algorithms. The main difficulties identified are the intricate setup and fine-tuning of the snakes parameters and the computer resources required by the algorithm. However, the experiments showed that the proposed algorithm is a valuable method for the automated generalization of polygonal subdivisions.

Using Neural Nets to Model the Spatial Distribution of Seasonal Homes

Bradley A. Shellito and Bryan C. Pijanowski

Seasonal and second homes are important aspects of recreational tourism. Owning a summer cottage, time-share condominium, hunting cabin, or a part-time residence in a location away from home affects development patterns in significant ways. This paper presents the results of using an artificial neural network and a geographic information systems-based approach to identify and quantify the principal predictors of seasonal home distribution within the Lake States region of Minnesota, Wisconsin, and Michigan. Representative variables, such as proximity and spatial configuration of lakes, proximity to the Great Lakes shore, surrounding forest acreage, and public land access have been quantified using geographic information systems at the minor civil division (MCD) scale for the three states. The GIS data have then been fed into artificial neural networks to enable these pattern recognition tools to identify the principal predictors of seasonal home distribution in the Upper Great Lakes States.

KEYWORDS: Seasonal homes, artificial neural networks, spatial modeling, Upper Great Lakes States

Letter to the Editor

Norman J. W. Thrower, University of California-Los Angeles

The exchange between Sara Irina Fabrikant and the McMasters (Robert and Susanna) in Cartography and Geographic Information Science, Volume 30, Number 1, January 2003, pp. 81-87, overlooked very important considerations, especially the cross-fertilization of European and American academic cartography. In the United States this field, in the first half of the twentieth century, was dominated by Hungarian-born and trained Erwin Josephus Raisz. Raisz served as a cartographer in the Austro-Hungarian Army in World War I and brought the rich traditions of central European mapping to the United States, where he served successively on the faculties of Columbia University, Harvard University, the University of Virginia, and the University of Florida. Raisz’s General Cartography, 1938, and later editions, was the leading text used in U.S. college cartography courses until eclipsed by Arthur H. Robinson’s Elements of Cartography, 1953, and successive editions (with other authors) to the end of the twentieth century. Robinson, Canadian-born and partly educated in England, was greatly influenced by the thematic cartography of that country and of France as evidenced, respectively, by his seminal articles: "The 1837 Maps of Henry Drury Harness," The [British] Geographic Journal, 121 (1955); and "The Thematic Maps of Charles Joseph Minard," Imago Mundi 21 (1967). It is not necessary to list all the cartographers from other countries who have come to the United States from the time of the visit of Alexander von Humboldt to President Jefferson in 1804, to appreciate the debt of U.S. cartography to Europe and beyond. The influences have not been entirely one way, especially with recent developments in computer graphics, animation, GIS, GPS, and remote sensing of the environment. But the point to be made is that cartography, more than most subjects is, by its nature, international, global, and extra-terrestrial!