COMPONENTS OF GIS
Hardware: It consists of the computer system on which the GIS software will run. The choice of hardware system ranges from Personal Computers to multi user Super Computers. These a computers should have essentially an efficient processor to run the software and sufficient memory to store enough information (data).
Software: GIS software provides the functions and tools needed to store, analyze, and display geographic information. The software available can be said to be application specific. All GIS software generally fit all these requirements, but their on screen appearance (user interface) may be different.
Data: Geographic data and related tabular data are the backbone of GIS. It can be collected in-house or purchased from a commercial data provider. The digital map forms the basic data input for GIS. Tabular data related to the map objects can also be attached to the digital data. A GIS will integrate spatial data with other data resources and can even use a DBMS.
Method: A successful GIS operates according to a well-designed plan, which are the models and operating practices unique to each task. There are various techniques used for map creation and further usage for any project. The map creation can either be automated raster to vector creator or it can be manually vectorized using the scanned images. The source of these digital maps can be either map prepared by any survey agency or satellite imagery.
People: GIS users range from technical specialists who design and maintain the system to those who use it to help them perform their everyday work. GIS operators solve real time spatial problems. They plan, implement and operate to draw conclusions for decision making.
Network: With rapid development of IT, today the most fundamental of these is probably the network, without which no rapid communication or sharing of digital information could occur. GIS today relies heavily on the Internet, acquiring and sharing large geographic data sets.
Although it is very easy to purchase the constituent parts of a GIS (the computer hardwareand basic software), the system functions only when the requisite expertise is available, thedata are compiled, the necessary routines are organized, and the programs are modified tosuit the application. A computer system can function at what may appear to be lightning speed, yet the entire time span of a GIS project can stretch to months and even years. These facets of an overall GIS are interlinked. In general, procurement of the computer hardware and software is vital but straightforward. The expertise required is often underestimated, the compilation of data is expensive and time consuming, and the organizational problems can be most vexing. These facets of an overall GIS are discussed in detail later.
Traditionally, geographical data are presented on maps using symbols, lines, and colours. Most maps have a legend in which these elements are listed and explained – a thick black line for main roads, a thin black line for other roads, and so on. Dissimilar data can be superimposed on a common coordinate system. Consequently, a map is both an effective medium for presentation and a bank for storing geographical data. But herein lies a limitation. The stored information is processed and presented in a particular way, usually for a particular purpose. Altering the presentation is seldom easy. A map provides a static picture of geography that is almost always a compromise between many differing user needs. Nevertheless, maps are a substantial public asset. Surveys conducted in Norway indicate that the benefit accrued from the use of maps is three times the total cost of their production. Compared to maps, GIS has the inherent advantage that data storage and data presentations are separate. As a result, data may be presented and viewed in various ways. Once they are stored in a computer, we can zoom into or out of a map, display selected areas, make calculations of the distance between places, present tables showing details of features shown on the map, superimpose the map on other information, and even search for the best locations for retail stores. In effect, we can produce many useful products from a single data source.
The term geographical information system (GIS) is now used generically for any computer-based capability for the manipulation of geographical data. GIS is computer-based capability for the manipulation of geographical data. A GIS includes not only hardware and software, but also the special devices used to input maps and to create map products, together with the communication systems needed to link various elements. The hardware and software functions of a GIS include:
Compilation
• Storage
• Updating and changing
• Management and exchange
• Manipulation
• Retrieval and presentation
• Acquisition and verification
• Analysis and combination
All of these actions and operations are applied by a GIS to the geographical data that form its database. All of the data in a GIS are georeferenced, that is, linked to a specific location on the surface of the Earth through a system of coordinates. One of the commonest coordinate systems is that of latitude and longitude; in this system location is specified relative to the equator and the line of zero longitude through Greenwich, England. But many other systems exist, and any GIS must be capable of transforming its georeferences from one system to another.
Geographical information attaches a variety of qualities and characteristics to geographical locations (Figure 1.10). These qualities may be physical parameters such as ground elevation, soil moisture level, or classifications according to the type of vegetation, ownership of land, zoning, and so on. Such occurrences as accidents, floods, or landslides may also be included. We use the general term attributes to refer to the qualities or characteristics of places, and think of them as one of the two basic elements of geographical information, along with locations. In some cases, qualities are attached to points, but in other cases they refer to more complex features, either lines or areas, located on the Earth’s surface; in such cases the GIS must store the entire mapped shape of the feature rather than a simple coordinate location. Examples of commonly mapped features are lakes, cities, counties, rivers, and streets, each with its set of useful attributes. When a feature is used as a reporting zone for statistical purposes, a vast amount of information may be available to be used as attributes for the zone in GIS. In market research, for example, it is common for postal codes to be used as the basisfor reports on demographics, purchasing habits, and housing markets.
A GIS can process georeferenced data and provide answers to questions involving, e.g., the particulars of a given location, the distribution of selected phenomena, the changes that have occurred since a previous analysis, the impact of a specific event, or the relationships and systematic patterns of a region. It can perform analyses of georeferenced data to determine
the quickest driving route between two points and help resolve conflicts in planning by calculating the suitability of land for particular uses.
A GIS can process georeferenced data and provide answers to questions involving, e.g., the particulars of a given location, the distribution of selected phenomena, the changes that have occurred since a previous analysis, the impact of a specific event, or the relationships and systematic patterns of a region. It can perform analyses of georeferenced data to determine the quickest driving route between two points and help resolve conflicts in planning by calculating the suitability of land for particular uses.
Hardware: It consists of the computer system on which the GIS software will run. The choice of hardware system ranges from Personal Computers to multi user Super Computers. These a computers should have essentially an efficient processor to run the software and sufficient memory to store enough information (data).
Software: GIS software provides the functions and tools needed to store, analyze, and display geographic information. The software available can be said to be application specific. All GIS software generally fit all these requirements, but their on screen appearance (user interface) may be different.
Data: Geographic data and related tabular data are the backbone of GIS. It can be collected in-house or purchased from a commercial data provider. The digital map forms the basic data input for GIS. Tabular data related to the map objects can also be attached to the digital data. A GIS will integrate spatial data with other data resources and can even use a DBMS.
Method: A successful GIS operates according to a well-designed plan, which are the models and operating practices unique to each task. There are various techniques used for map creation and further usage for any project. The map creation can either be automated raster to vector creator or it can be manually vectorized using the scanned images. The source of these digital maps can be either map prepared by any survey agency or satellite imagery.
People: GIS users range from technical specialists who design and maintain the system to those who use it to help them perform their everyday work. GIS operators solve real time spatial problems. They plan, implement and operate to draw conclusions for decision making.
Network: With rapid development of IT, today the most fundamental of these is probably the network, without which no rapid communication or sharing of digital information could occur. GIS today relies heavily on the Internet, acquiring and sharing large geographic data sets.
Although it is very easy to purchase the constituent parts of a GIS (the computer hardwareand basic software), the system functions only when the requisite expertise is available, thedata are compiled, the necessary routines are organized, and the programs are modified tosuit the application. A computer system can function at what may appear to be lightning speed, yet the entire time span of a GIS project can stretch to months and even years. These facets of an overall GIS are interlinked. In general, procurement of the computer hardware and software is vital but straightforward. The expertise required is often underestimated, the compilation of data is expensive and time consuming, and the organizational problems can be most vexing. These facets of an overall GIS are discussed in detail later.
Traditionally, geographical data are presented on maps using symbols, lines, and colours. Most maps have a legend in which these elements are listed and explained – a thick black line for main roads, a thin black line for other roads, and so on. Dissimilar data can be superimposed on a common coordinate system. Consequently, a map is both an effective medium for presentation and a bank for storing geographical data. But herein lies a limitation. The stored information is processed and presented in a particular way, usually for a particular purpose. Altering the presentation is seldom easy. A map provides a static picture of geography that is almost always a compromise between many differing user needs. Nevertheless, maps are a substantial public asset. Surveys conducted in Norway indicate that the benefit accrued from the use of maps is three times the total cost of their production. Compared to maps, GIS has the inherent advantage that data storage and data presentations are separate. As a result, data may be presented and viewed in various ways. Once they are stored in a computer, we can zoom into or out of a map, display selected areas, make calculations of the distance between places, present tables showing details of features shown on the map, superimpose the map on other information, and even search for the best locations for retail stores. In effect, we can produce many useful products from a single data source.
The term geographical information system (GIS) is now used generically for any computer-based capability for the manipulation of geographical data. GIS is computer-based capability for the manipulation of geographical data. A GIS includes not only hardware and software, but also the special devices used to input maps and to create map products, together with the communication systems needed to link various elements. The hardware and software functions of a GIS include:
Compilation
• Storage
• Updating and changing
• Management and exchange
• Manipulation
• Retrieval and presentation
• Acquisition and verification
• Analysis and combination
All of these actions and operations are applied by a GIS to the geographical data that form its database. All of the data in a GIS are georeferenced, that is, linked to a specific location on the surface of the Earth through a system of coordinates. One of the commonest coordinate systems is that of latitude and longitude; in this system location is specified relative to the equator and the line of zero longitude through Greenwich, England. But many other systems exist, and any GIS must be capable of transforming its georeferences from one system to another.
Geographical information attaches a variety of qualities and characteristics to geographical locations (Figure 1.10). These qualities may be physical parameters such as ground elevation, soil moisture level, or classifications according to the type of vegetation, ownership of land, zoning, and so on. Such occurrences as accidents, floods, or landslides may also be included. We use the general term attributes to refer to the qualities or characteristics of places, and think of them as one of the two basic elements of geographical information, along with locations. In some cases, qualities are attached to points, but in other cases they refer to more complex features, either lines or areas, located on the Earth’s surface; in such cases the GIS must store the entire mapped shape of the feature rather than a simple coordinate location. Examples of commonly mapped features are lakes, cities, counties, rivers, and streets, each with its set of useful attributes. When a feature is used as a reporting zone for statistical purposes, a vast amount of information may be available to be used as attributes for the zone in GIS. In market research, for example, it is common for postal codes to be used as the basisfor reports on demographics, purchasing habits, and housing markets.
The relationships between geographical features often provide vital information. For example, the connections of a water supply pipe network may be critical for technicians, who need to know which valves to close in order to increase water pressure in certain sectors. The details of properties bordering a road are necessary if all property owners affected by roadwork are to be properly notified. Connections between streets are important in using a GIS to assist drivers in navigating around an unfamiliar city. The ability of a GIS to store relationships between features in addition to feature locations and attributes is one of the most important sources of the power and flexibility of this technology. Some GISs can even store flows and other measures of interaction between features, to support applications in transportation, demography, communication, and hydrology, among other areas. Stored data may be processed in a GIS for presentation in the form of maps, tables, or special formats. One major GIS strength is that geographical location can be used to link information from widely scattered sources. Because the geographical location of every item of information in a GIS database is known, GIS technology makes it possible to relate the quality of groundwater at a site with the health of its inhabitants, to predict how the vegetation in an area will change as the irrigation facilities increases, or to compare development proposals with restrictions on land use. This ability to overlay gives GIS unique power in helping us to make decisions about places and to predict the outcomes of those decisions. The only requirement is that the geographical information from each source be expressed in compatible georeferencing systems.
A GIS can process georeferenced data and provide answers to questions involving, e.g., the particulars of a given location, the distribution of selected phenomena, the changes that have occurred since a previous analysis, the impact of a specific event, or the relationships and systematic patterns of a region. It can perform analyses of georeferenced data to determine
the quickest driving route between two points and help resolve conflicts in planning by calculating the suitability of land for particular uses.
A GIS can process georeferenced data and provide answers to questions involving, e.g., the particulars of a given location, the distribution of selected phenomena, the changes that have occurred since a previous analysis, the impact of a specific event, or the relationships and systematic patterns of a region. It can perform analyses of georeferenced data to determine the quickest driving route between two points and help resolve conflicts in planning by calculating the suitability of land for particular uses.
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