| GIS is the abbreviation of Geographical Information System. It is a geographical research technology that was quickly boomed from 1960s. It is a comprehensive science of computer science, mapping and remote sensing, geography, environmental science, space science, information and management science.Along with the development of computer technology and the serious request of information visualization, GIS is becoming a promising branch in the field of computer application technology, which is more and more mature too. Statistics show that more than 85 percent of the information on the earth is of geographical information. It is said that the 21st century will become a geographical information century. Geographical information technology will penetrate into everywhere in people's life. Almost every department such as electric power, telecommunication, irrigation works and police cannot do without GIS. Therefore it is valuable and practicable to study GIS.Based on the practical request of power network, this paper first analyzes the defaults of general GIS software tool-poor extensibility, strict request of computer hardware and software and high development costs. Then according to the current technology of GIS and the latest development trend of the computer software technology, it proposed a primitive Components GIS spatial data organization model making use of the object-oriented technology. It also brings forward a method of how to take advantage of the object-oriented idea to store the spatial data and the property data consistently into the relational database and set up a spatial index. At last combined with the county power network system, a special Components GIS control is developed, and centered on it a HuaXian power network system is further developed using the integrated development tool-PowerBuilder 8.0.This paper is composed of eight chapters:The first chapter is an introduction. It roughly describes the research background and the main tasks achieved by it.Chapter 2 is about GIS. Firstly, it explains the concept of GIS, the function of GIS, GIS's application and development trend. Secondly, it points out that Components GIS will be the main stream of GIS in the future. At last it explains the characters of Components GIS.Chapter 3 is about the related technologies of developing Components GIS control. In this chapter, two main technologies in developing controls-object-oriented technology and component technology are introduced. Inthe section of object-oriented technology, the basic concept of object-oriented, developing method of object-oriented and the merits of object-oriented programming are explained. In the section of component technology, the source of component technology, COM/DCOM and ActiveX are explained.Chapter 4 is about analysis and design of Components GIS controls. It proposed the questions that should pay attention when design a general Components GIS control, they are the customization of controls, the selection of data model of controls, the organization of controls' spatial data and property data and the optimization of controls.Chapter 5 explains the general design and analysis of Components GIS in the power network. This is one of the centers of the paper. It has detailed descriptions of the general strategies in developing GIS controls, such as the selection of data store mode, efficient organization of spatial data and property data and the optimization rules of controls etc.Chapter 6 refers to the special development and realization of Components GIS of power network. It comprises the key questions in the course of developing GIS controls. The questions are: how to divide the classes in programs, the layer relationship of classes, the definition of classes, the partial realizations of graphical operations, the interfaces between control and exterior program, and the interfaces between control and database etc.Chapter 7 concisely explains a practical Components GIS control application-HuaXian Power Network GIS System. It describes the design... |
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