| We have written this book to help practitioners design and implement multiuser, multiunit GISs to assist in their spatial decision-making.These are called corporate or enterprise GISs.We presume that you know what a GIS is, already have some experience with GIS, and have some ideas about what it can do.We also assume you are interested in improving the design of your existing GIS or building a well-designed system that will meet your needs. In our review of the existing material on GIS we felt that there was a missing piece in an accessible book.There is a lot of information on design and implementation in hundreds of needs assessments and database documentation files and probably thousands of public and private documents in the hands of organizations and consulting companies that have implemented GISs. But that information is very hard to come by and is usually specifically tailored for the particular application. At the other end of the generality scale, books on relational database design do not contain information on how to deal with spatial data, the “where” of things, and they usually are aimed at a business market with examples drawn from the world of commerce.Knowing how to design an inventory control or billing information system is a useful exercise, but it doesn’t help a GIS practitioner in local government design a database to support planning and zoning activities. Our goal in this book is to deal explicitly with the issues of spatial data in designing and implementing a GIS and to provide examples useful to the GIS community.
Having said that we assumed you knew what a GIS was before picking up this book,we feel an obligation to define it anyway. So, to repeat what has been circulating in the information technology (IT) and GIS literature, vendor brochures, countless figures, and PowerPoint slides, a GIS is composed of
- People—the users of the system
- Applications—the processes and programs they use to do their work
- Data—the information needed to support those applications
- Software—the core GIS software
- Hardware—the physical components on which the system runs
Versions of these components of a GIS have been circulating in the literature and vendor brochures for years.They certainly predate GIS specifically and are applicable to any information system. Although it is common to represent the five elements, or components, in some kind of mandala diagram where everything appears to be connected to everything else,we do not find that very useful, so we have added the key relationships. Figure 1.1 should be read as a sentence, and it proceeds from the most important elements to the least important elements. |
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