Showing papers in "Cartography and Geographic Information Science in 2001"
TL;DR: In this article, the authors present research challenges in Geovisualization, and present a survey of the most important challenges in this area. Cartography and Geographic Information Science: Vol. 28, No. 1, pp. 3-12.
Abstract: (2001). Research Challenges in Geovisualization. Cartography and Geographic Information Science: Vol. 28, No. 1, pp. 3-12.
637 citations
TL;DR: In this article, a study of 159 counties in the eastern US using county choropleth data and ancillary land-use data and polygonal (vector) and grid (raster) dasymetric methods were tested and evaluated map accuracy using both statistical analyses and visual prese
Abstract: Dasymetric maps display statistical data in meaningful spatial zones Such maps can be preferable to choropleth maps that show data by enumeration zones, because dasymetric zones more accurately represent underlying data distributions Though dasymetric mapping has existed for well over a century, the methods for producing these maps have not been thoroughly examined In contrast, research on areal interpolation has been more thorough and has examined methods of transferring data from one set of map zones to another, an issue that is applicable to dasymetric mapping Inspired by this work, we tested five dasymetric mapping methods, including methods derived from work on areal interpolation Dasymetric maps of six socio-economic variables were produced fm a study area of 159 counties in the eastern US using county choropleth data and ancillary land-use data Both polygonal (vector) and grid (raster) dasymetric methods were tested We evaluated map accuracy using both statistical analyses and visual prese
481 citations
TL;DR: It is argued that cognitive and usability issues should be considered in the context of six major research themes: 1) geospatial virtual environments (GeoVEs); 2) dynamic representations (including animated and interactive maps); 3) metaphors and schemata in user interface design; 4) individual and group differences; 5) collaborative geovisualization; and 6) evaluating the effectiveness of geov isualization methods.
Abstract: We provide a research agenda for the International Cartographic Association's Commission on Visualization and Virtual Environment Working Group on Cognitive and Usability Issues in Geovisualization. Developments in hardware and software have led to (and will continue to stimulate) numerous novel methods for visualizing geospatial data. It is our belief that these novel methods will be of little use if they are not developed within a theoretical cognitive framework and iteratively tested using usability engineering principles. We argue that cognitive and usability issues should be considered in the context of six major research themes: 1) geospatial virtual environments (GeoVEs); 2) dynamic representations (including animated and interactive maps); 3) metaphors and schemata in user interface design; 4) individual and group differences; 5) collaborative geovisualization; and 6) evaluating the effectiveness of geovisualization methods. A key point underlying our use of theoretical cognitive principles is tha...
343 citations
TL;DR: In this article, a new conceptual framework is proposed for organizing data about such complex geographic phenomena in a GIS as a hierarchy of events, processes, and states, where discrete objects are used to show how events and processes progress in space and time.
Abstract: Conventionally, spatial data models have been designed according to object- or field-based conceptualizations of reality. Conceptualization of complex geographic phenomena that have both object- and field-like properties, such as wildfire and precipitation, has not yet been incorporated into GIS data models. To this end, a new conceptual framework is proposed in this research for organizing data about such complex geographic phenomena in a GIS as a hierarchy of events, processes, and states. In this framework, discrete objects are used to show how events and processes progress in space and time, and fields are used to model how states of geographic themes vary in a space-time frame. Precipitation is used to demonstrate the construction and application of the proposed framework with digital precipitation data from April 15 to May 22, 1998, for the state of Oklahoma, U.S.A. With the proposed framework, two sets of algorithms have been developed. One set automatically assembles precipitation events and proce...
165 citations
TL;DR: Issues and challenges in interface development and usage that are identified as paramount within the geospatial visualization community are addressed.
Abstract: User interfaces for geospatial information are the tools by which users interact with and explore that information. The provision of appropriate interface tools for exploiting the potential of cont...
108 citations
TL;DR: The paper stresses the need for the closer integration of three largely disparate technologies: geographic visualization, knowledge discovery in databases, and geocomputation.
Abstract: This paper details the research agenda of the International Cartographic Association Commission on Visualization: Working Group on Database-Visualization Links. The paper stresses the need for the closer integration of three largely disparate technologies: geographic visualization, knowledge discovery in databases, and geocomputation. The introduction explains the meaning behind these terms, the ethos behind their practice, and their connections within the broad realm of knowledge construction activities. The state of the art is then described for different approaches to knowledge construction, concentrating where possible on visual and geographically oriented methods. From these sections, a research agenda is synthesized in the form of three sets of research questions addressing: (1) visual approaches to data mining; (2) visual support for knowledge construction and geocomputation; and (3) databases and data models that must be satisfied to make visually-led knowledge construction a reality in the geogra...
106 citations
TL;DR: A research agenda is presented which addresses the current role and potential of map displays and the important links between representation and the user interface, map user cognition and the geospatial database are stressed.
Abstract: A research agenda is presented which addresses the current role and potential of map displays. By considering the geospatial data used in visualization, the form and design of maps, the purposes for which map displays are created, the nature of the map user community, and the technology employed to visualize geospatial data, a thorough overview of the nature of cartographic visualization is given. Under the same themes, and sourced in cartographic tradition, cartographic practice and technological opportunities, a series of possible research avenues are highlighted. The important links between representation and the user interface, map user cognition and the geospatial database are stressed.
82 citations
TL;DR: In this article, the authors explore the role of the University of Wisconsin-Milwaukee and its efforts to provide equitable public access to GIS through university/community partnerships, and conclude that the initiatives contain contradictory impulses of creating simultaneous empowerment of community organizations and their dependen...
Abstract: By virtue of its cost and technological complexity, GIS has been critiqued as an elitist anti-democratic technology. In response there has been an ongoing proliferation of public participation GIS (PPGIS) initiatives in order to facilitate citizen participation in planning. It is critical to conduct case study research ofthese initiatives, in order to identify factors and conditions fostering sustainable PPGIS initiatives at the local level. Through the case of Milwaukee, this paper explores the local contextual factors and the network of actors and institutions that foster the PPGIS process in that city. Particular attention is paid to the role of the University of Wisconsin-Milwaukee and its efforts to provide equitable public access to GIS through university/community partnerships. The paper critically explores the PPGIS initiatives undertaken in Milwaukee and concludes that the initiatives contain contradictory impulses of creating simultaneous empowerment of community organizations and their dependen...
63 citations
TL;DR: In this paper, the authors present a survey of methods for symbolizing map projection distortion, with each method described and illustrated in graphical form, under ten separate headings organized from simple to more complex in terms of interpretation.
Abstract: One of the most fundamental steps in map creation is the transformation of information from the surface of a globe onto a flat map. Mapmakers have developed and used hundreds of different map projections over the past 2,000 years, yet there is no perfect choice because every map projection uniquely alters some aspect of space during the transformation process. Detailed information about the type, amount, and distribution of distortion is essential for choosing the best projection for a particular map or data set. The distortion inherent in projections can be measured and symbolized much like any other map variable. Methods for symbolizing map projection distortion are reviewed, with each method described and illustrated in graphical form. The symbolization methods are collected under ten separate headings organized from simple to more complex in terms of interpretation. Most of these methods are highly effective at communicating distortion, yet they are rarely used beyond textbooks and technical documenta...
43 citations
TL;DR: It is shown how geography-based classifications of urban districts can be related to available thematic characteristics by applying the data mining algorithms classification tree derivation, attribute weighting, and subgroup discovery.
Abstract: We present new methods for analyzing geo-referenced statistical data. These methods combine visualization and direct manipulation techniques of exploratory data analysis and algorithms for data mining. The methods have been implemented by integrating two hitherto separate software tools: Descartes for interactive thematic mapping, and the data mining toolbox Kepler. In using these tools, data analysis may proceed as a steady interaction between visual inspiration and insights gained from mathematical–statistical calculations. After introducing the various components of the methods and tools, the paper guides the reader through in-depth examples of using the tools in the context of analysis of urban demographic data. In particular, it is shown how geography-based classifications of urban districts can be related to available thematic characteristics by applying the data mining algorithms classification tree derivation, attribute weighting, and subgroup discovery.
42 citations
TL;DR: In this paper, the accuracy of raster projection was analyzed by two methods: 1) a set of 12 one-degree by 1-degree quadrilaterals placed at various latitudes was projected at several raster resolutions and compared to the projection of a vector representation of the same quadricaterals, and 2) several different raster resolution of land cover data for Asia were projected and the total areas of 21 land cover categories were tabulated and comp...
Abstract: High-resolution regional and global raster databases are currently being generated for a variety of environmental and scientific modeling applications. The projection of these data from geographic coordinates to a plane coordinate system is subject to significant areal error. Sources of error include users selecting an inappropriate projection or incorrect parameters for a given projection, algorithmic errors in commercial geographic information system (GIS) software, and errors resulting from the projection of data in the raster format. To assess the latter type of errors, the accuracy of raster projection was analyzed by two methods. First, a set of 12 one-degree by one-degree quadrilaterals placed at various latitudes was projected at several raster resolutions and compared to the projection of a vector representation of the same quadrilaterals. Second, several different raster resolutions of land cover data for Asia were projected and the total areas of 21 land cover categories were tabulated and comp...
TL;DR: In this paper, the authors examine the sources and effects of local shape uncertainty in line and surface models and discuss individual factors affecting local shape in each step of the line or surface modeling process.
Abstract: Modeling line or surface phenomena digitally involves two tasks: discretization of the phenomenon, which yields a finite set of data, and subsequent interpolation, which reconstructs the continuum. Many mathematical techniques exist for the latter task, and most methods require a number of parameters to be specified. The shape of digital line or surface models between the data points (that is, the local shape) and the information derived from these models both depend on the selected method and, possibly, on the specification of parameters. The reconstruction of the continuum thus introduces uncertainty. This paper examines the sources and effects of this type of uncertainty. For this purpose, the modeling of lines and surfaces is separated into an abstraction, an implementation, and measurement. The individual factors affecting uncertainty of local shape in each step are identified and discussed. The paper concludes that local shape uncertainty, unlike positional uncertainty of given data, cannot be numer...
TL;DR: In this paper, the authors modified Tanaka's method by basing thickness of contour lines on twice the cosine of the angle between the surface normal and the illumination vector, which is most commonly used in analytical hill shading.
Abstract: Visualization of topography can be greatly facilitated by the illuminated contour method. This method, popularized in a hand-drafted map by Tanaka, uses a gray background with black and white contours. A direction of illumination is assumed, and white contours represent illummated topography, while black contours represent non-illuminated or shaded areas. Additionally, thickness of contours varies with the cosine of the angle between the azimuth of maximum slope (i.e., aspect) and the azimuth of illumination. We modified Tanaka's method by basing thickness of contour lines on twice the cosine of the angle between the surface normal and the illumination vector. The cosine of this angle is most commonly used in analytical hill shading. In addition, we present maps with changes in other visual variables and offer our evaluations. Lines with gray tones instead of black and white lines do not improve the illumination effect. We believe variations in the colors of contours and background with elevation can visu...
TL;DR: Quality is critical in cartography because key decisions are often made based on the information the map communicates as mentioned in this paper, which can also affect the economics of map production by diverting a sizeable portion of production cost to pay for rework on maps with poor quality.
Abstract: Quality is critical in cartography because key decisions are often made based on the information the map communicates. The mass production of digital cartographic information to support geographic information science has now added a new dimension to the problem of cartographic quality, as problems once limited to small volumes can now proliferate in mass production programs. These problems can also affect the economics of map production by diverting a sizeable portion of production cost to pay for rework on maps with poor quality. Such problems are common to general industry—in response, the quality engineering profession has developed a number of successful methods to overcome these problems. Two important methods are the reduction of error through statistical analysIs and addressing the quality environment in which people work. Once initial and obvious quality problems have been solved, outside influences periodically appear that cause adverse variations in quality and consequently increase production c...
TL;DR: Mapping Census 2000: The Geography of U.S. Diversity as mentioned in this paper is an atlas containing 75 maps and presenting county and state-level data for Census 2000, which includes counts of people who indicated more than one race.
Abstract: Mapping Census 2000: The Geography of U.S. Diversity is an atlas containing 75 maps and presenting county- and state-level data for Census 2000. Cynthia Brewer and Trudy Suchan rapidly produced the atlas in the Population Division of the U.S. Census Bureau using ArcInfo 8.1 prerelease software. Redistricting data, on which the atlas was based, were released in March 2001 and the full-color atlas went to press in July 2001. It is the first decennial atlas produced by the Census Bureau in 80 years. Race maps in the atlas are designed to present the new Census 2000 data that include counts of people who indicated more than one race. Choropleth classifications are constructed to facilitate comparison among maps in series for all race/ethnicity groups, both large and small. Map series share breaks that are adjusted to include meaningful breaks based on overall U.S. percentages for individual groups. Additional shared meaningful breaks, such as "no change" and "50 percent of the population" also anchor classifi...
TL;DR: A distributed object technology, the Common Object Request Broker Architecture (CORBA), is introduced; an architecture for web-based mapping using CORBA is proposed; and a prototype implementation of the architecture is presented.
Abstract: 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 intro...
TL;DR: An algorithm for extracting high-point locations from statistical surface data using map algebra and local neighborhood analysis via three key parameters: minimum vertical gain, vertical gain neighborhood, and horizontal separation neighborhood is introduced and tested.
Abstract: We introduce and test an algorithm for extracting high-point locations from statistical surface data. The algorithm uses map algebra and local neighborhood analysis via three key parameters: minimum vertical gain, vertical gain neighborhood, and horizontal separation neighborhood. Though the method is applicable to any x,y,z data set, we tested it on 1:250,000 digital elevation models (DEMs) for Arizona. The resulting high points were compared quantitatively with an independent data set of named summits from the USGS Geographic Names Information System (GNIS). The comparison showed that, on an aggregate basis, the extraction method can approximate the number and spatial pattern of high points when compared to the GNIS points. However, extraction by neighborhood analysis may consistently misdiagnose certain features, such as the edges of troughs (e.g., canyon rims).