GIS Based Studies in the Humanities and Social Sciences - Chpater 8

8 How to Find Free Software Packages for Spatial Analysis via the Internet Atsuyuki Okabe, Atsushi Masuyama, and Fumiko Itoh CONTENTS 8.1 Introduction ...............................................................................................113 8.2 Search Engine at the CSISS Web Site.....................................................114 8.3 FreeSAT: A Web System for Finding Free Spatial Analysis Tools.....115 8.3.1 The home page of FreeSAT.........................................................115 8.3.2 The “Spatial Analysis for Points” Page.....................................116 8.3.3 The “Spatial Analysis for Networks” Page ..............................117 8.3.4 The “Spatial Analysis for Attribute Values of Areas” Page........119 8.3.5 The “Spatial Analysis for Continuous Surfaces Page” ..........121 8.3.6 Tables of Software Names ...........................................................122 8.4 Conclusion ..................................................................................................124 References.............................................................................................................125 8.1 Introduction Researchers in the humanities and social sciences, as shown in Part 3 of this volume, analyze many phenomena that are caused by, or related to, spatial factors. When the number of factors is small, spatial analysis with manual methods is tractable, but when the number is large, the analysis is laborious, and it often becomes intractable. A few decades ago, researchers themselves used to develop computer programs to alleviate this task. However, the task required not only pro-gramming skills but also a lot of program-development time. As a result, the use of spatial analysis had very limited application to the humanities and social sciences. Nowadays, this difficulty has been overcome, largely by the introduction of Geographical Information Systems (GIS). 113 Copyright © 2006 Taylor & Francis Group, LLC 114 GIS-based Studies in the Humanities and Social Sciences The ordinary GIS software provides many basic tools for spatial analysis (for example, “Spatial Analysts” in ArcGIS). However, when we wish to carry out advanced spatial analysis, the tools provided by ordinary GIS software are not always sufficient, and we have to find advanced ways. Fortunately, a considerable number of tools for advanced spatial analysis have been developed by the GIS community (Walker and Moor, 1988; Haslett et al., 1990; Openshaw et al., 1990; Openshaw et al., 1991; Okabe and Yoshikawa, 2003), and information about these tools is posted on the World Wide Web. Such information is, however, scattered over the Web, and it is difficult to find an appropriate tool for a specific spatial-analysis application. In fact, Google shows more than 3 million Web sites referring to “spatial analysis.” The objective of this chapter is to introduce Web-based sites that are able to diminish this difficulty. We first briefly introduce one of the most powerful search engines, served by the Center for Spatially Integrated Social Sciences (CSISS). Second, we show a Web-based system for finding free software packages for advanced spatial analysis, sited at the Center for Spatial Information Science (CSIS). 8.2 Search Engine at the CSISS Web Site The CSISS Web site (www.csiss.org/search) provides five types of search engines: 1. Search for spatial resources. 2. Search the site. 3. Search social-science data archives. 4. Search for spatial tools. 5. Search of spatial-analysis literature in the social sciences. All of these search engines are useful for studies in the humanities and social sciences, but the major concern of this chapter is with spatial tools, 4. Clicking on 4 gives a dialog box, which asks us to enter a keyword for our specific spatial analysis; for example, “point pattern,” in which case, 164 items will appear. The information included in these items is classified into three types. 1. Description of methods for spatial analysis. 2. List of Web sites dealing with methods for spatial analysis. 3. Web sites providing software packages for spatial analysis. Copyright © 2006 Taylor & Francis Group, LLC How to Find Free Software Packages for Spatial Analysis via the Internet 115 The first type of information does not provide tools. The second type of information does not directly provide tools, but users may surf further to find a tool in the list. The last type of information does provide tools, but they may not be free. It is noted that users cannot specify the last type of information when they enter a keyword. Therefore, they have to examine 164 items to find an appropriate tool for their use. Professional spatial ana-lysts can manage this task, but inexperienced or intermediate analysts may be overwhelmed by the huge amount of information. If they are particularly looking for free tools, much time is needed to find them. To overcome this difficulty, the Web system shown in the next section is developed. 8.3 FreeSAT: A Web System for Finding Free Spatial Analysis Tools This section introduces FreeSAT, a system for finding Web sites that provide Free Spatial Analysis Tools, originally developed by Itoh and Okabe (2003). The address is ua.t.u-tokyo.ac.jp/okabelab/freesat/. 8.3.1 The home page of FreeSAT The home page looks like this. Welcome to FreeSAT: AWeb system for finding Free SpatialAnalysis Tools Version 2.0 developed by A. Masuyama, A. Okabe and F. Itoh 1. Spatial analysis for points 2. Spatial analysis for networks 3. Spatial analysis for attribute values of areas 4. Spatial analysis for continuous surfaces FreeSAT classifies spatial analyses into four types: analysis for points, analysis for networks, analysis for attribute values of areas, and analysis for continuous surfaces. The first type of analysis deals with the distribution of point-like features, for example, the distribution of convenience stores in a region (Figure 8.1a). The second type of analysis deals with network-like features, for example, streets, railways, sewage, rivers, and so forth (Figure 8.1b). The third type of analysis deals with the attribute data of areas con-stituting a region; for example, population data by municipal districts (Figure 8.1c). The last type of analysis deals with an attribute value that is continu-ously distributed over a region, such as precipitation (Figure 8.1d). Users are required to choose the type of analysis suitable to their study. Copyright © 2006 Taylor & Francis Group, LLC 116 GIS-based Studies in the Humanities and Social Sciences (a) (b) (c) (d) FIGURE 8.1 Examples of methods: (a) analysis for points, (b) analysis for networks, (c) analysis for attribute values of areas, and (d) analysis for continuous surfaces. 8.3.2 The “Spatial Analysis for Points” Page Suppose that we want to analyze spatial patterns of point-like features (such as convenience stores in a city, as in Figure 8.1a). In this case, we click on “Spatial Analysis for Points” on the FreeSAT home page, and the following page appears. 1. SPATIAL ANALYSIS FOR POINTS 1.1 Point density estimation 1.2 Tests for clustered, random or dispersed 1.2.1 Quadrat method 1.2.2 Nearest neighbor distance method 1.2.3 Ripley’s K function and L-function 1.3 Detection of clusters 1.3.1 Detection of spatial clusters 1.3.2 Detection of spatio-temporal clusters Copyright © 2006 Taylor & Francis Group, LLC How to Find Free Software Packages for Spatial Analysis via the Internet 117 FIGURE 8.2 Point density estimation. (a) (b) (c) FIGURE 8.3 Point patterns: (a) clustered, (b) random, and (c) dispersed. The methods are classified into three classes, namely “Point density esti-mation,” “Test for clustered, random or dispersed,” and “Detection of clus-ters.” The first class (Section 1.1) deals with methods for estimating the density (indicated by the lightness of the gray color in Figure 8.2) from a given set of points (indicated by the points in Figure 8.2). The second class of methods (Section 1.2) tests whether points are clustered (Figure 8.3a), random (Figure 8.3b), or dispersed (Figure 8.3c). This test may be carried out using the “Quadrat,” “Nearest neighbor distance,” or “Ripley’s K function and L function” method. The first method (Section 1.2.1) tests randomness in terms of the number of points in regularly shaped cells (e.g., squares) (Figure 8.4a). The second method (Section 1.2.2) tests randomness in terms of the distance from each point to its nearest point (Figure 8.4b). The third method (Section 1.2.3) tests randomness in terms of the cumulative number of points as a function of the distance from each point (Figure 8.4c). The last class of methods (Section 1.3) detects clustered points in a plane (two-dimensional space) (Figure 8.5a) and in a spatio-temporal space (three-dimensional space) (Figure 8.5b). 8.3.3 The “Spatial Analysis for Networks” Page Suppose that we next want to analyze network-like features, such as railways and roads, as in Figure 8.1b. In this case, we click on “Spatial Copyright © 2006 Taylor & Francis Group, LLC ... - tailieumienphi.vn