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1. Introduction Chapter-Introduction GIS 1. INTRODUCTION. Geography is the study of Earth’s features and patterns of their variations in spatial location and time. Many questions of agricultural production are geographic in nature as the production depends on the environment and prevailing socio economic conditions, both of which vary spatially and in time. Examples are questions related to natural resources management, precision agriculture, agro- ecological classification for land use planning, regional trends and patterns in technology adaptation, agricultural productivity and income, non-Pont source pollution from agricultural lands, etc. Answering these questions requires access to large volumes of multidimensional geographical (spatial) information of weather, soils, topography, water resources, socio economic status, etc. Further, answers to even apparently simple questions require that the data from several sources be integrated in a consistent form. Geographical Information Systems or GIS enable representation and integration of such spatial information. Geographic information systems (GIS) (also known as Geospatial information systems) are Computer Software and hardware systems that enable users to capture, store, analyze and manage spatially referenced data. GISs have transformed the way spatial (geographic) data, relationships and patterns in the world are able to be interactively queried, processed, analyzed, mapped, modelled, visualized, and displayed for an increasingly large range of users, for a multitude of purposes. In a general sense, the term describes any information system that integrates, stores, edits, analyzes, shares, and displays geographic information. GIS applications are tools that allow users to create interactive queries (user-created searches), analyze spatial information, edit data in maps, and present the results of all these operations. Geographic information science is the science underlying geographic concepts, applications, and systems It is a special case of information system where the database consists of observations on spatially distributed features, activities or events, which are definable in space as points, lines or area. A geographic information systems manipulates data about these points, lines and areas to retrieve data for ad hoc queries and analyses. Whether siting a new business, finding the best soil for growing bananas, or figuring out the best route for an emergency vehicle, local problems also have a geographical component GIS will give you the power to create maps, integrate information, visualize scenarios, solve complicated problems, present powerful ideas, and develop effective solutions like never before. GIS is a tool used by individuals and organizations, schools, governments, and businesses seeking innovative ways to solve their problems. Today, GIS is a multibillion-dollar industry employing hundreds of thousands of people worldwide. GIS is taught in schools, colleges, and universities throughout the world. Professionals in every field are increasingly aware of the advantages of thinking and working geographically. Geographic: 80% of government data collected is associated with some location in space. Information: attributes, or the characteristics (data), can be used to symbolize and provide further insight into a given location. Chapter-Introduction GIS System: a seamless operation linking the information to the geography – which requires hardware, networks, software, data, and operational procedures. GIS is: • Not just software!!! • Not just for making maps!!! GIS can be used as synonymous to: . GI Systems: A computerized tool that helps solve geographic problems. GI Science: The development of data models, algorithms, and methods for representing geography and spatial relationships in order to support spatial analysis and location-based computing . GI Studies: The systematic study of society’s use of geographic information, including institutional, organizational and procedural issues. GI Services: The business of providing GIS data and analysis tools to GIS users (often by chaining interoperable components in logo-block fashion). 1.1. OVERVIEW, HISTORY AND CONCEPT OF GIS 1.1.1. Overview A geographic information system consists of the tools and services necessary to allow one to collect, organize, manipulate, interpret, and display geographic information. A GIS is more than just the hardware and software familiar to most people; it extends to the staff who operate the system, the databases, the physical facilities, and the organizational commitment necessary to make it all work. A GIS can be defined by how it is used (e.g., a land information system, a natural resource management information system), by what it contains (spatially distinct features, activities, or events defined as points, lines, polygons, or raster grid cells), by its capabilities (a powerful set of tools for collecting, storing, retrieving, transforming, and displaying spatial data), or by its role in an organization (a map production system, a spatial analysis system, a system for assisting in making decisions regarding basic geographic questions: where is it? what is it? why is it there?). GIS can also be defined as geographic information science (GIScience). GIScience involves the identification and study of issues that are related to GIS use, that affect its implementation, and that arise from its application (Goodchild 1992). In short, GIScience not only encourages users to understand the benefits of GIS technology in providing a powerful set of analysis tools but also encourages users to view the technology as part of a broader discipline that promotes geographic thinking and problem-solving strategies as being useful to society. The development of GIScience is an outgrowth of the fact that GIS technology is available to more users today than ever before and that spatial categorization and analysis is applicable to many issues and problems of society. Regardless of how a GIS is perceived or used, it is the integration of the various tools and services that leads to a successful GIS. Although other software programs perform GIS-like tasks (e.g., database management, graphics, or computer-assisted drafting [CAD] Software), a GIs is unique in its ability to allow users to create, maintain, and analyze geographic or spatial data. The term spatial data implies that data exist - which not only describe landscape features (e.g., condition, Chapter-Introduction GIS composition, structure of forests) but also reference the location where the features can be found. A GIs allows one to manipulate spatial data and to analyse quickly a large volume of spatial data. A GIS stores spatial data in a digital database files, often referred to as themes, maps, covers, and tables, layers, or GIS databases. The terminology for referring to a GIS database varies, depending on the GIs software program being used. In most GIs software programs, similar landscape features are maintained in a single GIS database. For instance, one may have a soils GIS database, which contains the soil characteristics of a landscape, or a wildlife GIS database, which contains the nest locations of a single species of animal or a group of species of animals. GIs allows the integration and simultaneous examination of multiple GIS databases through a process described as overlay analysis. Overlay analysis represents the essence of what many consider to be a primary role of GIS in natural resource management: the ability to combine two or more GIS databases to assist in making decisions. GIS is related to a number of other fields and disciplines, including computer-assisted drafting (CAD), computer cartography, database management, and remote sensing. In fact, GIs contains certain aspects of each of these fields and, thus, is closely related to each of them. However, the differences between GIS and these other allied fields is notable. For example, most CAD software programs have rudimentary links to a database management system, whereas GIs software programs generally have strong links to a database management system. The field of computer cartography emphasizes map production, but although the databases used may be similar to those used in GIS, computer cartography generally puts less emphasis on the nongraphic attributes of spatial landscape features than does GIS. Database management software programs have the ability to store and manage the location and attribute data of landscape features but generally lack the display capabilities of GIS, CAD, and computer cartography. Types of GIS • There are a number of Geographical Information Systems (GIS) (or GIS software) available today. • They range from high-powered analytical software to visual web applications, and each of those are used for a different purpose. • These can be categorized into 3 main groups of GIS: 1. Web-based GIS 2. Geobrowser 3. Desktop GIS Web-based GIS • Web-based GIS, or WebGIS, are online GIS applications which in most cases are excellent data visualisation tools. • Their functionality is limited compared to software stored on your computer, but they are user-friendly and particularly useful as they not required data download. Chapter-Introduction GIS Browsers Applications Web Web Server Broker Services ( built on .Net, SOAP/XML, Java API) Dallas Delhi Durban Databases Fig: General Web-based GIS Application Architecture There are different map servers and mapping client application that can be used while developing WebGIS applications. Web map servers • GeoServer:
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