【正文】 f flag = 1 Then Circle (zd(i, j).X, zd(i, j).Y), p / qp End If End If j = j + 1 Loop i = i + 1 LoopEnd SubPrivate Sub Form_Load() sum = 0End SubPrivate Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single) If sum = 4 Then 39。畫任意多邊形 your(sum).X = X your(sum).Y = Y If sum = 1 Then Line (your(sum 1).X, your(sum 1).Y)(your(sum).X, your(sum).Y) End If If sum = 4 Then Line (your(0).X, your(0).Y)(your(4).X, your(4).Y) End If sum = sum + 1 End IfEnd Sub附錄二：外文原文　　　 Implementing geoportals: applications of distributed GISAbstract As GIS implementations mature and GIS use expands beyond the current core GIS munity the need to discover and disseminate GIS capabilities grows. The Internet and the age of distributed puting provide the technical framework on which distributed GIS is built. As key application of distributed GIS, geoportals provide a gateway to discover and access geographic Web services. Four key geoportal projects are presented that help to define distributed GIS, and illustrate the challenges to be met in order to achieve the goal of wider GIS usage. 1. Introduction Since the late 1990s, the geographic industry has seen increasing interest and activity in the deployment of web sites that provide access to geographic content. There are several drivers behind this activity. One is the advent of the World Wide Web and an interest by many industries to harness it to help drive growth. At the same time, the GIS industry itself has e of age. This maturation has led to a new phase of growth for the industry that focuses on dissemination of geographic knowledge and capabilities. Finally, there is an increasing recognition in business, both public and private, that geographic content and GIS capabilities add value to many business processes. Geographic portals represent an applied response to this need to disseminate geographic data and leverage the GIS munity
s substantial investment in GIS capabilities and content. Over the last six years the GIS munity has bee increasingly focused on the dissemination of GIS capabilities within, as well as outside of, organizations. There is recognition within the munity that the web provides a new medium for participation, and its response has e in the form of software technologies that provide the capability to implement GIS in a distributed environment. To build effective, relevant technology, GIS vendors have traditionally worked with key users and partners to implement solutions that both satisfy the requirements of specific projects and foster the development of core software that supports these and other customer deployments. During the last six years the author has participated in GIS vendor–user partnerships on four major projects that have pushed the limits of GIS technology beyond the desktop architecture to distributed GIS. The experiences gained in implementing these projects point the way to using Internet technologies to disseminate GIS capabilities. This paper reviews the four key projects, the stages of distributed GIS they represent, and the lessons that have been learned from them to date. These projects help us to see how to evolve geoportal applications into truly distributed GIS. Additionally, a definition of geoportals is presented from an industry perspective, and the GIS system ponents and standards needed to support portal implementations are discussed. Finally, this paper outlines a way forward for geoportals and distributed GIS, the challenges to be faced, and the rewards to be gained. 2. What is a geoportal? A technical definition of the word ‘‘portal’’ is ‘‘a(chǎn) web site considered to be an entry point to other web locations’’ (). Append the term ‘‘geo,’’ and the result might be as follows. Geoportal: a web site that presents an entry point to geographic content on the web or, more simply, a web site where geographic content can be discovered. Many web sites, however, have some association with geographic content or functions. For example, most web sites representing businesses have, at a minimum, addresses for the business locations on their sites, and many have links to map images depicting these locations. What then is the defining characteristic that differentiates a geoportal from other web sites with some geographic content? In most sites, geographic content supports the site but is not the site
s primary focus. So to refine the definition further, a geographic portal is a web site where the discovery of geographic content is a primary focus. 3. The technology of geoportals: distributed GIS Prior to the advent of the Internet, GIS technology, like other software technologies, was limited to the domain of desktop, workstation and in limited cases, serverbased puting platforms. The physical restrictions of these puting platforms confined GIS to only supporting the evolution of project and departmental GIS. Distributed puting has provided the foundational standards and technology on which the Internet and distributed GIS are built. The Internet consists of information technology standards, such as, Transmission Control Protocol/Internet Protocol (TCP/IP), Hyper Text Transport Protocol (HTTP), Hyper Text Markup Language (HTML), and eXtensible Markup Language (XML) as well as software, physical puting, and network infrastructure. The GIS industry has, in turn, exploited these technologies to build the capabilities known as distributed GIS. Distributed GIS is simply GIS technology that has been built and deployed using the standards and software of the Internet. The great benefit of distributed GIS is that many GI systems can be linked and accessed as a single virtual system. A key challenge for distributed GIS is the publishing of geographic content. The publishing process takes place in two steps. The first is the preparation of