Showing papers in "Journal of Geographical Systems in 2004"

The roles of geography markup language (GML), scalable vector graphics (SVG), and Web feature service (WFS) specifications in the development of Internet geographic information systems (GIS)

Abstract: The objective of this paper is to address two issues of current Internet Geographic Information Systems (GIS) programs – interoperability and graphic image output issues – using standard-based technologies, specifically, the Geography Markup Language (GML), Scalable Vector Graphics (SVG) and the OpenGIS Web Feature Service (WFS) Implementation Specifications developed by the OpenGIS Consortium (OGC). A strategy is proposed to use GML as a coding and data transporting mechanism to achieve data interoperability, SVG to display GML data on the Web, and WFS as a data query mechanism to access and retrieve data at the feature level in real time on the Web. Two case studies are reported to implement this strategy. Our case studies show that the combination of GML, SVG, and WFS has an immense potential to achieve interoperability while not requiring considerable changes to existing legacy data. Data can be in their original formats and still be retrieved using WFS and transformed into GML in real time. SVG can produce superior quality vector maps on a Web browser. More research is needed to explore the full potential of these new standards and to test them in real-world situations.

The role of the map in a web - GIS environment

Abstract: The World Wide Web has changed the perspective on the role that maps can play. Their traditional function remains, e.g. to represent an abstraction of a selected part of reality to offer insight into geospatial patterns and relations. Additionally the map can be an important part of a search engine, especially in the context of geospatial data infrastructure. Maps can also function as an interface to other geographic and non-geographic information on the Web. The question ‘What are the implications of this expanding role of maps for a WebGIS environment?’ is addressed in this paper.

The potential of Web-based GIS

Abstract: and integrated tools for storing, manipulating, visualizing, and analyzing spatial data. As a new and emerging technology in the early 1970s, GIS had a profound influence on the capabilities of geographic analysis, and in retrospect marked a turning point in the reinforcement of geography as an explicitly spatial discipline. Also, at that time and on a parallel course, ArpaNet – the first established prototype of the Internet networking system, followed by an adoption of the Transmission Control Protocol/Internet Protocol (TCP/IP) in 1980s – was a force in the rapid development of Information Technology and Telecommunications (Comer 2000). The benefits of the implementation of the HyperText Markup Language (HTML), the HyperText Transfer Protocol (HTTP), and the World Wide Web (henceforth referred to as Web) as one of the main application of the Internet in the early 1990s was beginning to be recognized in GIS research (Hardie, 1998). GIS are usually centralized and need knowledgeable users for effective operation. With Internet technology, GIS was now able to make its concepts more open, accessible, and mobile to everyone thereby facilitating notions such as democratization of spatial data, open accessibility, and effective dissemination. In 1993 the Xerox Corporation developed its Map Viewer as the first experimental tool for interactive spatial data exploration over the Web. In 1994, The Alexandria Digital Library Project funded by the US National Science Foundation established the first distributed library service for spatially referenced data. With a short history of only about 10 years, the integration of the Internet and GIS technology has produced an expanding area of research referred to as Web-based GIS, Internet GIS, On-line GIS, and Internet distributed GIServices. Early implementations were mainly dissemination of static maps, then interactive maps with pan-identify-zoom features, support for client/ server designs, and advanced cartographic and geo-visualization tools (Kraak and Brown 2001). Out of this progression, Internet-based GIS emerged and expanded to yield Internet distributed GIServices with the capabilities to interact with multiple and heterogeneous systems and servers that support more advanced GIS functions. The expansion of Internet-based J Geograph Syst (2004) 6:79–81 DOI: 10.1007/s10109-004-0133-4

Web-based Analytical Tools for the Exploration of Spatial Data

Abstract: This paper deals with the extension of internet-based geographic information systems with functionality for exploratory spatial data analysis (esda). The specific focus is on methods to identify and visualize outliers in maps for rates or proportions. Three sets of methods are included: extreme value maps, smoothed rate maps and the Moran scatterplot. The implementation is carried out by means of a collection of Java classes to extend the Geotools open source mapping software toolkit. The web based spatial analysis tools are illustrated with applications to the study of homicide rates and cancer rates in U.S. counties.

A Web GIS collaborative framework to structure and manage distributed planning processes

Abstract: Rapidly changing planning contexts, new stakeholder demands, and intensified natural resource conflicts have resulted in questions about the adequacy of traditional resource planning. These questions include the lack of representation of some stakeholder groups (equity) and the inability to actively participate (access) in the planning stages due to the synchronous and place-based protocols of the process. A deficiency in equity and access reduces the wider acceptance of planning outcomes and on claims about democratic decision-making. In this study, the Web GIS Collaborative Spatial Delphi framework was designed to create a distributed, collaborative, and continual setting to address equity and access. Cognitive mapping, the Delphi procedure, and consensus approaches are the main components integrated to structure a shared virtual space for problem-solving and planning. Web mapping tools, priority ranking and rating, exploratory map analysis, and data visualizations provide analytical support. The framework is based on participant recommendations from summative evaluations of four planning workshops. The implications of the framework and future directions are discussed. This research is part of a wider program to design effective planning and decision-making tools on the Web.

Integrating web-based GIS and image processing tools for environmental monitoring and natural resource management

Abstract: The combined powers of Web-based geographic information systems (GIS) and on-line remote sensing tools can significantly reduce the high cost and labor associated with environmental monitoring and natural resource management. This paper introduces an integrated Web-based GIS architecture by combining three levels of geographic information services (GIServices): data archive, information display, and spatial analysis. A prototype Web site, WGAT (Web-based GIS and Analytic Tools), has been developed to provide easy access of geospatial information and to facilitate Web-based image analysis and change detection capabilities for natural resource managers and regional park rangers. The Web-based integration framework emphasizes user-oriented services, distributed network environments, metadata standards, communication protocols, client/server computation, and ubiquitous access.

Geospatial data resampling and resolution effects on watershed modeling: A case study using the agricultural non-point source pollution model

Abstract: Researchers have been coupling geographic information systems (GIS) data handling and processing capability to watershed and water-quality models for many years. This capability is suited for the development of databases appropriate for water modeling. However, it is rare for GIS to provide direct inputs to the models. To demonstrate the logical procedure of coupling GIS for model parameter extraction, we selected the Agricultural Non-Point Source (AGNPS) pollution model. Investigators can generate data layers at various resolutions and resample to pixel sizes to support models at particular scales. We developed databases of elevation, land cover, and soils at various resolutions in four watersheds. The ability to use multiresolution databases for the generation of model parameters is problematic for grid-based models. We used database development procedures and observed the effects of resolution and resampling on GIS input datasets and parameters generated from those inputs for AGNPS. Results indicate that elevation values at specific points compare favorably between 3- and 30-m raster datasets. Categorical data analysis indicates that land cover classes vary significantly. Derived parameters parallel the results of the base GIS datasets. Analysis of data resampled from 30-m to 60-, 120-, 210-, 240-, 480-, 960-, and 1920-m pixels indicates a general degradation of both elevation and land cover correlations as resolution decreases. Initial evaluation of model output values for soluble nitrogen and phosphorous indicates similar degradation with resolution.

A Web-based environmental decision support system (WEDSS) for environmental planning and watershed management

Abstract: Many of the largest problems faced by local governments such as cities and counties involve issues associated with urbanization. The increased rate of urbanization has led to haphazard growth, increased infrastructure costs, deterioration of living conditions and worsening of the environment. This phenomenon places a heavy burden on local planners and managers, who struggle to balance competing demands for residential, commercial, and industrial development with imperatives to minimize environmental degradation. In order to effectively manage this development process on a sustainable basis, local government planners increasingly rely on the use of information technologies, spatial modeling techniques (Dragicevic et al. 2000) and Spatial Decision Support Systems (SDSS) (Fedra 1995; Sugumaran et al. 2000; Sugumaran and Sugumaran, 2007; Sugumaran, and Bakker, 2007; Zhang et al. 2008). These technologies and techniques include combinations of remote sensing, GIS, spatial modeling, Multi-Criteria Evaluation (MCE), computational neural networks, and Internet technology.

A general framework for error analysis in measurement-based GIS Part 1: The basic measurement-error model and related concepts

Abstract: This is the first of a four-part series of papers which proposes a general framework for error analysis in measurement-based geographical information systems (MBGIS). The purpose of the series is to investigate the fundamental issues involved in measurement error (ME) analysis in MBGIS, and to provide a unified and effective treatment of errors and their propagation in various interrelated GIS and spatial operations. Part 1 deals with the formulation of the basic ME model together with the law of error propagation. Part 2 investigates the classic point-in-polygon problem under ME. Continuing to Part 3 is the analysis of ME in intersections and polygon overlays. In Part 4, error analyses in length and area measurements are made. In this present part, a simple but general model for ME in MBGIS is introduced. An approximate law of error propagation is then formulated. A simple, unified, and effective treatment of error bands for a line segment is made under the name of “covariance-based error band”. A new concept, called “maximal allowable limit”, which guarantees invariance in topology or geometric-property of a polygon under ME is also advanced. To handle errors in indirect measurements, a geodetic model for MBGIS is proposed and its error propagation problem is studied on the basis of the basic ME model as well as the approximate law of error propagation. Simulation experiments all substantiate the effectiveness of the proposed theoretical construct.

A general framework for error analysis in measurement-based GIS

Abstract: This is the first part of our four-part series of papers which proposes a general framework for error analysis in measurement-based geographical information systems (MBGIS). The purpose of the series is to investigate the fundamental issues involved in measurement error (ME) analysis in MBGIS, and to provide a unified and effective treatment of errors and their propagations in various interrelated GIS and spatial operations. Part 1 deals with the formulation of the basic ME model together with the law of error propagation. Part 2 investigates the classic point-in-polygon problem under ME. Continued onto Part 3 is the analysis of ME in intersections and polygon overlays. In Part 4, error analyses in length and area measurements are made. In the present part, a simple but general model for ME in MBGIS is introduced. An approximate law of error propagation is then formulated. A simple, unified, and effective treatment of error bands for a line segment is made under the name of “covariance-based error band”. A new concept, called “maximal allowable limit”, which guarantees invariance in topology or geometric-property of a polygon under ME is also advanced. To handle errors in indirect measurements, a geodetic model for MBGIS is proposed and its error distribution problem is studied on the basis of the basic ME model as well as the approximate law of error propagation. Simulation experiments all substantiate the effectiveness of the proposed theoretical construct.

Democratic input into the nuclear waste disposal problem: the influence of geographical data on decision making examined through a web-based GIS

Abstract: This paper elucidates the manner in which users of an online decision support system respond to spatially distributed data when assessing the solution to environmental risks, specifically, nuclear waste disposal. It presents tests for revealing whether users are responding to geographical data and whether they are influenced by their home location (Not in My Back Yard – style behavior). The tests specifically cope with problems associated with testing home-to-risk distances where both locations are constrained by the shape of the landmass available. In addition, we detail the users’ wider feelings towards such a system, and reflect upon the possibilities such systems offer for participatory democracy initiatives.

Development and application of a livable environment evaluation support system using Web GIS

Abstract: This research proposes a Web-Service that supports the interpretation of the local environment objectively through visualized spatial information, and evaluation of the value subjectively through interactive interfaces. This article focuses on the livable environment whose criteria have become diversified in recent years. In order to highlight such varieties of values during evaluation, the proposed system, LEES (Livable Environment Evaluation-support System) aids exploratory evaluating process by: 1) clarifying ambiguous preferences of livability using a Fuzzy Structure Model, 2) analyzing areas using multi-criteria according to the individual preference structure, and 3) visualizing distributions of the results for supporting decision-making. In order to validate this system, sensitivities of typical preference scenarios are analyzed. Additional uses of this Web GIS-based system are also discussed. An empirical study directly involving citizens is in progress to improve the social effectiveness of the system.

A general framework for error analysis in measurement-based GIS. Part 4: Error analysis in length and area measurements

Abstract: This is the final of a series of four papers on the development of a general framework for error analysis in measurement-based geographic information systems (MBGIS). In this paper, we discuss the error analysis problems in length and area measurements under measurement error (ME) of the defining points. In line with the basic ME model constructed in Part 1 of this series, we formulate the ME models for length and area measurements. For length measurement and perimeter measurement, the approximate laws of error propagation are derived. For area measurement, the exact laws of error propagation are obtained under various conditions. An important result is that area measurement is distributed as a linear combination of independent non-central chi-square variables when the joint ME vectors of vertices coordinates are normal. In addition, we also give a necessary and sufficient condition under which the area measurement estimator is unbiased. As a comparison, the approximate law of error propagation in area measurement is also considered and its approximation is substantiated by numerical experiments.

Channels of synthesis forty years on: Integrated analysis of spatial economic systems

Abstract: Isard’s vision of integrated modeling that was laid out in the 1960s book Methods of Regional Science provided a road map for the development of more sophisticated analysis of spatial economic systems. Some forty years later, we look back at this vision and trace developments in a sample of three areas – demographic-econometric integrated modeling, spatial interaction modeling, and environmental-economic modeling. Attention will be focused on methodological advances and their motivation by new developments in theory as well as innovations in the applications of these models to address new policy challenges. Underlying the discussion will be an evaluation of the way in which spatial issues have been addressed, ranging from concerns with regionalization to issues of spillovers and spatial correlation.

On design and implementation of an object-relational spatial database for activity/travel behaviour research

Abstract: The development of micro level models of urban processes has partially been facilitated by increased availability of detailed activity/travel survey data. Managing and exploring these data can be resource intensive and time consuming. Researchers and municipal planning organizations increasingly face information management challenges. This paper reviews an experiment in design and implementation of an object-relational geographic database using the principles of object-orientation. A data model is specified using the Unified Modeling Language notation and a visual modeling tool, and then implemented as an object-relational spatial database. The resulting database acts as an information foundation capable of supporting empirical research and application development. The experience suggests that a formal approach to information management can enhance our understanding of complex activity/travel data contributing to informed application of these data to transportation research questions.

A general framework for error analysis in measurement-based GIS Part 2: The algebra-based probability model for point-in-polygon analysis

Abstract: This is the second paper of a four-part series of papers on the development of a general framework for error analysis in measurement-based geographic information systems (MBGIS). In this paper, we discuss the problem of point-in-polygon analysis under randomness, i.e., with random measurement error (ME). It is well known that overlay is one of the most important operations in GIS, and point-in-polygon analysis is a basic class of overlay and query problems. Though it is a classic problem, it has, however, not been addressed appropriately. With ME in the location of the vertices of a polygon, the resulting random polygons may undergo complex changes, so that the point-in-polygon problem may become theoretically and practically ill-defined. That is, there is a possibility that we cannot answer whether a random point is inside a random polygon if the polygon is not simple and cannot form a region. For the point-in-triangle problem, however, such a case need not be considered since any triangle always forms an interior or region. To formulate the general point-in-polygon problem in a suitable way, a conditional probability mechanism is first introduced in order to accurately characterize the nature of the problem and establish the basis for further analysis. For the point-in-triangle problem, four quadratic forms in the joint coordinate vectors of a point and the vertices of the triangle are constructed. The probability model for the point-in-triangle problem is then established by the identification of signs of these quadratic form variables. Our basic idea for solving a general point-in-polygon (concave or convex) problem is to convert it into several point-in-triangle problems under a certain condition. By solving each point-in-triangle problem and summing the solutions, the probability model for a general point-in-polygon analysis is constructed. The simplicity of the algebra-based approach is that from using these quadratic forms, we can circumvent the complex geometrical relations between a random point and a random polygon (convex or concave) that one has to deal with in any geometric method when probability is computed. The theoretical arguments are substantiated by simulation experiments.

A general framework for error analysis in measurement-based GIS Part 3: Error analysis in intersections and overlays

Abstract: This is the third of a four-part series on the development of a general framework for error analysis in measurement-based geographic information systems (MBGIS). In this paper, we study the characteristics of error structures in intersections and polygon overlays. When locations of the endpoints of two line segments are in error, we analyze errors of the intersection point and obtain its error covariance matrix through the propagation of the error covariance matrices of the endpoints. An approximate law of error propagation for the intersection point is formulated within the MBGIS framework. From simulation experiments, it appears that both the relative positioning of two line segments and the error characteristics of the endpoints can affect the error characteristics of the intersection. Nevertheless, the approximate law of error propagation captures nicely the error characteristics under various situations. Based on the derived results, error analysis in polygon-on-polygon overlay operation is also performed. The relationship between the error covariance matrices of the original polygons and the overlaid polygons is approximately established.

Isard's contributions to spatial interaction modeling

Abstract: This short review, surveys Isard’s role in promoting what has become known as spatial interaction modeling. Some contextual information on the milieu from which his work emerged is given, together with a selected number of works that are judged to have been influenced (directly and indirectly) by his work. It is suggested that this burgeoning field owes a lot to the foundations laid in the gravity model chapter of “Methods”. The review is supplemented by a rather extensive bibliography of additional works that are indicative of the breadth of the impact of this field.

An elliptical basis function network for classification of remote sensing images

Abstract: An elliptical basis function (EBF) network is employed in this study for the classification of remotely sensed images. Though similar in structure, the EBF network differs from the well-known radial basis function (RBF) network by incorporating full covariance matrices and employing the expectation-maximization (EM) algorithm to estimate the basis functions. Since remotely sensed data often take on mixture-density distributions in the feature space, the network not only possesses the advantage of the RBF mechanism, but also utilizes the EM algorithm to compute the maximum likelihood estimates of the mean vectors and covariance matrices of a Gaussian mixture distribution in the training phase. Experimental results show that the EM-based EBF network is more effective in training and simpler in structure than an RBF network constructed for the same task.

Distributional properties of georeferenced random variables based on the eigenfunction spatial filter

Abstract: The eigenfunction spatial filter derives from the Moran Coefficient that indexes spatial autocorrelation Mean, variance and statistical distribution characterizations and descriptions of georeferenced random variables and their interrelationships are derived in terms of the eigenfunction spatial filter Selected comparisons are made with spatial autoregressive model results Implications of the eigenfunction spatial filter are outlined for simulation experiments, variance components of correlation coefficients, missing values estimation, and non-normal georeferenced random variables Particularly unanticipated findings include: spatial filtering reveals the potential need to employ a spatial autocorrelation reduction stepwise regression variable selection criterion, the standard error of a univariate mean can be expressed in terms of a conventional regression variance inflation factor that captures spatial autocorrelation effects, spatial autocorrelation can simultaneously inflate and deflate a bivariate correlation coefficient, simulation experiments can be easily designed to involve specific map patterns associated with non-zero spatial autocorrelation, spatial filtering furnishes a convenient way to estimate missing georeferenced values, and the asymptotic variance of the Moran Coefficient is unaltered by spatial filtering

Transportation geography: The influence of Walter Isard and regional science

Abstract: This paper explores the influence of Walter Isard, his work, and the field of regional science generally on transportation geography. It argues that Isard’s impact was both subtle and significant. Regional science greatly influenced the emergence of modern transportation geography in the 1950s. Transportation themes and methods from Isard’s own work provided early building blocks for transportation geography. Moreover, Isard and regional science contributed importantly to the development of the intellectual network of persons, places, and institutions that early on defined the subfield. Regional science and transportation geography have diverged in recent decades, but opportunities exist for renewed interaction.

Geographic intersections of regional science: Reflections on Walter Isard's contributions to geography

Abstract: In his writing, analyses, and commentaries, Walter Isard contributed significantly to economic geography, inspiring a generation of economic geographers with seminal texts on industrial location and spatial economics and methods of regional analysis – a line of argumentation that explicitly incorporated abstract economic reasoning into an otherwise largely descriptive and inventory-based subdiscipline of geography. His circumscribed view of regional development and industrial location helped precipitate the emergence of the critical turn in economic geography in the late 1970s. He was the one early modern 20th century economics author to successfully wed economics and a certain perspective on space.

The impacts of Walter Isard on geography

Abstract: In the course of preparing this paper, which initially focused solely on identifying the impacts of input-output analysis on geography, a much broader perspective on the impacts of Walter Isard on geography ultimately emerged. In the tradition of input-output analysis, these impacts are grouped into direct, indirect, and induced effects, and summarized under the heading of influence. Walter Isard touched the lives of many through personal relationships, books and articles, and an energetic devotion to and enthusiasm for the creation of a regional science association. The Regional Science Association and its publications supported something of a greenhouse environment in which the seedlings of GIS and scientific geography could take root, until they were well enough established to enter mainstream geography. While clearly not limited to geography, the fruits of Walter Isard’s labors continue to populate the discipline through his contemporaries, their students, students’ students, and so on. The formative years of both regional science and scientific geography left an indelible mark on the nature of geographic inquiry.

Walter Isard’s influence on analytical human geographic research

Abstract: of progress in spatial analysis’’, it seems appropriate to take a retrospective look at the intersection between regional science and human geography. This issue of the Journal of Geographical Systems brings together a collection of distinguished human geographers to examine this intersection by means of the theme: Walter Isard’s impact on research in human geography. Their contributions cover a broad selection of subfields from human geography including spatial analysis, economic geography, integrated modeling, transportation geography, input-output analysis, and spatial interaction modeling, among others. Within human geography the stature of regional science is an often debated topic. Far from generating creative tensions and more extensive cross-fertilization between the wider field of human geography and regional science, these debates have primarily served to entrench individual scholars into well-known camps. This might be taken to reflect dimly on the future of regional science. I would argue that such an interpretation would be wrong for several reasons. As my colleague Arthur Getis has noted, some of the most highly celebrated human geographers have been long-time members of the regional science community. Moreover, the interdisciplinary spirit in that community has been an enduring strength that predates a current emphasis on multidisciplinary research in the social sciences as well as across the physical and social sciences. Finally, the importance of an analytical approach to space in the social sciences has recently been acknowledged through the establishment of the Center for Spatially Integrated Social Sciences (Goodchild et al. 2000). Here again, regional science through the leadership of Walter Isard, has long championed this focus. At first glance, honoring Walter Isard through a series of scholarly reviews of the impacts he has had upon different areas of human geography appeared to be a relatively straightforward proposition to both myself and the authors. However, as the contributions were being developed, a common theme began to emerge suggesting that Isard’s influence on human geographic research has been profound, yet challenging to chronicle. A full accounting has required a mixture of comprehensive reviews of methodological developments in J Geograph Syst (2004) 6:3–6 DOI: 10.1007/s10109-003-0119-7