CaGIS vol. 31, no. 1

Geographic Data for Academic Research: Assessing Access Policies

Bastiaan van Loenen and Harlan J. Onsrud

Data availability is a key issue affecting the collective well-being of society. Economic and legal scholars have argued that the current, relatively open, access-to-data environment in the United States is beneficial to advancing knowledge and the economy. However, little empirical evidence exists to validate the extent to which various access policy environments do or do not contribute to the productivity of academic researchers. Our research aimed to evidence support or lack of support of various data policies in the context of access to, and use of, geographic data within the university research environment. We synthesized a set of twenty-three recommended access-to-data principles from recommendations set forth in the literature. An online questionnaire strove to gain sufficient information to determine whether recommended principles were adhered to in the acquisition of each specific data set and whether scientists were productive in their use of such data sets. Productivity was assessed in terms of five measures. We hypothesized that data-sharing relationships would be more productive for science if the data policies confronted by scientists in their use of digital geographic data conformed with the recommended policies advocated in the literature. The data indicated relatively clear statistical significance in testing the principles of “adherence to pricing at marginal cost or less” and “provision for availability of metadata.” Correlated with the productivity of scientists, the collected survey data evidenced non-support of the first principle and support of the second. The latter finding suggests that government, private sector, and academic suppliers of geographic data should give high priority to the documentation of metadata in order to stimulate the more widespread use of available spatial data. This article describes the survey and statistical methods employed in researching this problem and presents the results of testing the two recommended principles. The implications of the findings are discussed.

KEYWORDS: Geographic data, GIS, data access principles, productivity, measures of success, metadata, open access, cost recovery, t-test, chi square test

Extracting and Visualizing Individual Space-Time Paths: An integration of GIS and KDD in Transport Demand Modeling

Ali Frihida, Danielle J. Marceau, and Marius Thériault

The disaggregate activity-based approach for transport demand modeling requires the acquisition, management, analysis, and visualization of very large, multivariate spatial datasets in order to capture and extract meaningful spatio-temporal patterns and relationships. Knowledge Discovery in Databases (KDD) is a conceptual and methodological framework that was developed in the last decade to address the issue of transforming large amounts of raw geographic data into knowledge. Based on the KDD framework, this paper describes the steps involved to build individual space-time paths from an origin-destination survey and presents the functionalities of an object-oriented GIS prototype to extract and dynamically visualize individual space-time paths. The prototype sustains seamless spatio-temporal queries to the database and provides cast-based animation that mimics continuous individual movement on the street network.

Keywords: Object-oriented model, geographic information systems, knowledge discovery in databases, transport demand modeling

The Icon Imagemap Technique for Multivariate Geospatial Data Visualization: Approach and Software System

Xianfeng Zhang and Micha Pazner

The visualization of multivariate geospatial data is an important concern in environmental modeling, exploratory data analysis, and geographic/spatial applications. This paper presents an icon-based visualization technique designed for co-visualizing multiple layers of geospatial information. Icon imagemaps are based on a three-tiered image structure consisting of pixel, icon block, and image levels. In icon imagemaps it is icons rather than pixels that form meaningful visualization primitives. Graphically versatile aggregate icon constructs take several visual variables into consideration, such as color, length, width, orientation, shape, size, pattern, and texture, and thus can carry more information than conventional pixel images. The extension from pixels to icons in the icon imagemap technique enables raster GIS to represent multiple variables at a single location in the “simple” raster data model. The IconMapper software system was developed as an implementation of the icon imagemap visualization technique. The modeling of terrain traversability in the Las Vegas area was used as an example to test the usefulness of this visualization technique. This paper describes the icon imagemap approach (concept and design issues) and its implementation as a software tool. The relative simplicity and flexibility of the icon imagemap approach makes it a powerful tool for non-fused visualization of multivariate geospatial data.

KEYWORDS: Visualization, icon, icon imagemap, geospatial data, IconMapper system

Building and Road Generalization with the CHANGE Generalization Software Using Turkish Topographic Base Map Data

Oztug Bildirici

The CHANGE generalization software package developed by the University of Hanover was applied to Turkish topographic base map data. The package is capable of processing roads and buildings. Through support programs, several benefits were gained, including a reliable data conversion between the internal file format of the package and DXF, improved geometric quality of the building data before generalization, and statistical evaluation of generalization results. Because the package runs in batch mode, the ACAD MAP CAD and GIS software package was used as a graphic interface, which has more functionality than a simple interface in this study. The paper introduces a generalization approach which can be implemented in a practical setting. An overview of the results of the case study shows the evident applicability of this approach.

Book Reviews

Internet GIS: Distributed Geographic Information Services for the Internet and Wireless Networks by Zhong-Ren Peng and Ming-Hsiang Tsu. John Wiley & Sons, Ltd., 2003, 679 pp., $90.00. ISBN 0-471-35923-8. Reviewed by Suzana Dragicevic and Shivanand Balram, Spatial Analysis and Modeling Laboratory, Department of Geography, Simon Fraser University, Burnaby, B.C., Canada

Historical Atlas of Central Europe by Paul Robert Magocsi. The Washington University Press. 2002. ISBN 0-295-98146-6; paper 274pp. $45. ISBN 0-295-98146-6. 288p. Hardcover $75. Reviewed by Angie Cope, American Geographical Society Library, University of Wisconsin-Milwaukee.

The World Through Maps: A History of Cartography by John Rennie Short. Firefly Books. 2003. ISBN 1-55297-811-7. 224p. Hardcover $40. Reviewed by Chieko Maene, American Geographical Society Library, UW-Milwaukee.