Geographic Information System (GIS)
Geographic Information System (GIS)
It was in the U.S in the middle of 1960s that work on this system was begun for the first time. Aerial photography, agricultural information, forestry, soil, geology, and related maps were used in this system. Geographic Information System or (GIS) formed to provide a power for analyzing huge masses of geographic data when the science progress and access to computer and other technologies to work on local dot occurred in 1970s. In recent decades, because of spreading in computer technology, Geographic information technology gives us this possibility to maintain data related to geo data base in up to data state in addition to combine different data effectively. Nowadays, this system is used to do scientific research, manage resources, and make developmental programming.
Geographic Information System of GIS is a computer system to manage and analyze local information. This system is able to gather, save, analyze and display geographic (local) information.
Data in GIS is shown according their locations.
GIS technology give us some information to provide maps by collecting and combining ordinary databases. Imaging and using geographic analyzes. This information is used to reveal the events more apparently, to predicate the results and prepare maps.
Geographic term in a geographic information system, means the locations of data subjects according to geographic coordinates (longitude and latitude, Information term shows that data in GIS is organized to represent useful knowledge, not only in colorful maps of images but also in statistic graphics, diagram, and varied figure answers to do scientific researches system term means that GIS is made of many attached and dependent part for varied functions.
A GIS system includes a computer package (Software & Hardware) of programs with a user mediator which enables us to obtain special operation of aim.
Components of such a system are: users, soft wares, hard wars, information and methods
Component of a geographic information System
Components of such a system are:
1) User: One of the most significant items to succeed in using GIS technology is skill in selecting and using tools in a geographic information system in addition to recognizing the information well. This is responsibility or user.
2) Hard wares: Nowadays, GIS networks contain many X-station, work station, personal computers, printers and plater which represent software component of a geographic information system.
3) Software: To use a geographic information system more effectively, we should apply powerful and up-to-date soft wares.
4) Data: database is the heart of every GIS. In this database some questions are answered. For example: in which form? Where is it? And how is it related to other shapes?
5) Methods: Of the most important components in a GIS is right methods in using data to achieve out special purposes.
spatial data models:
We can not use geographic and computer information in real life directly because digital computers work based on digits or characters which kept in themselves as binary digits.
So, desired phenomena in real life should be represented symbolically. Thus, we should collect data firstly and them geological domain, structure, geophysical fetuses of every characteristics about the earth, the information of which is collected can be compressed in an access able way using symbolic models in computers.
Every geological map is a symbolic model because it's a simplified domain of a post of real life observed from a tiled geologist's point of view. Components of model we spoke about are local factors which have about the same entities in real life represented in map toy graphic symbols.
All models of spatial data are composed of separated local factors such as points, lines, Zones, volumes & surfaces. These spatial factors are determined by characteristics which are both spatial and non-spatial(Digital description of factors and their features form local data system).
Data input and Output
To be useful, a geographic information system should be able to receive and produce information effectively. Input and output functions of data are concepts by which a GIS communicate to the outside world.
Data inputs include the encoding process of data in a legible way so that they can be read by computer and putting data in database of GIS.
Data which can be recorded in GIS are of two types:
1) Spatial data showing geographic location of features (like points or lines that show geographic features such as street, lake and …).
2) non-spatial descriptive data which pay for factors like salinity of the waters of a lake and information such as name of a street.
Input of data to a geographic information system (GIS) can be in many forms, some of them are in figures, recording by keyboard, geometry of coordinates, hard digitizing (digitalizing), Scanning and recording existing digital files.
Data output is a process by which the information obtained by GIS can be represented in a suitable from.
Data can be existed in one of following three formats.
1. Hard Copy
(Permanent display such as information on a paper, photography titer and so on)
2. Soft Copy
(Display on computer screen)
(Out in electronic format containing computer files)
A sample of information output in hard copy format
Stages of establelishment and setting up GIS in project format.
Establishment and setting up GIS in project format include stages such as inputting managing, analyzing, manipulating and finally outputting data.
1. Data input
Data input factor turns data from existing form into a form usable in GIS. In this stage, data of geo data base are processed according to desired standards for the output exactness going to be provided. These data are in the form of paper maps, figures of descriptive information, electronic files and descriptive information related to these files.
2. Data Management
This stage contains function to store, maintain and recover existing information in database.
3. Data Manipulation and analysis
This stage includes a set of activities done on data by soft wares, hard wares and users to prepare and process them for the next stages
4. Data Output
The used output functions are determined based on users need. So output data are represented in different form like map, figures or hard copy and soft copy.
The purposes of a geographic information system:
The ultimate purpose of a geographic information system (GIS) is to support established decisions based on local data and it's main function is to obtain information gained by combining different layers of data in different ways and ideas.
The mentioned purpose is achieved by activities done on local data. These activities are:
1) Search: which is the action of searching series of organized data in databases of a geographic information system.
2) Organization: The main characteristics to organize data in this system is their local location.
3) Monitoring: GIS technology uses graphic abilities of computers to monitor information display is usually done by the video screen but other output instruments like colorful printers are also used to display printed copy.
4) Integration: another part of those activities are integrating series of local data from varied sources to display, understand and interpretation local phenomena. (These phenomena are invisible when local data are use separately.
5) Analysis: It is understanding and comprehension of data concepts and means analyzing local data.
6) Prediction: usually the purpose of studying local data in a geographic information system is prediction.
In fact, a geographic information system (GIS) prepares work abilities to collect, input, process, change the form, display, combine, search, analyze, model and output all local data according to desired purposes.
Different applications of GIS:
Nowadays, because of science and computes system progress, we can use GIS in many fields like geology, ecological studies, water resources and watershed management, agriculture, forestry, education, urban applications, trade industry, organizations, … Some of them so applications are:
Geology: analyzing geological information in a zone to explore a mine, petroleum of a other aims is basically a composite process of different data.
A geologist tries to find useful structures in a zone by relating different geological data, thus to be effective, all geological data should be analyzed by their locations.
By preparing display possibility & analysis of different data, GIS enables the geologist to work on varied data more exactly. Accurately and in a way that's fairly impossible by analogue and traditional methods.
Generally, we can explain the application of GIS in geology as follows:
To provide maps of mineral potential: The aim of combing information gained by informational, geological, geochemical, geophysical, remote sensing, and economic geology, dispersion of deposits and mineral indices of zone layers is to provide a map representing zones which most probably have mineralization based on metalogical model of the zone.
To provide maps of natural disasters: These maps describe slope stability. Land slides, zoning of earthquake damages, eruptions, damages resulted from stream flood and tsunami, local erosion, dangers poor mining industrial activity, global warming and etc.
Site selection maps which means to select suitable sites to perform engineering projects such as burial of redundant materials, pipelines, road, railroad, dams and expansion & development of building construction.
- Varied geological processing to evaluate resources like water, sand & gravel, construction stone, crude oil, natural gas, coal, geotropism energy in addition to metal minerals.
- Exploratory researches to identify mutual relationships among data series during the geological research like understanding geochemical and geophysical signals of granites with S and I types, or evaluate signals resulted from satellite images related to litho logy and vegetation.
- Environment: Studying water, Boil and air pollution and finally providing maps to protect the environment.
- Water resources and watershed management: discovering underground water resources and studying surface water.
Agriculture and programming for land use:
Nowadays, many organization related to agriculture and land use apply GIS technology For example, data related to land use and meteorology resulted from satellite, earth measurements and information connected to the not year crops can be analyzed altogether to predict the amount of a crop of several kinds of crops in zone.
Forestry and wildlife management
We can constantly and daily update the maps of forests by using of GIS. Additionally GIS can be applied to analyze and save information related to the forests such as the amount of wood we can cut in a zone, studying the fire distribution in the forest or evaluation programs related to the wood cut where as many of these analyses can't be done without GIS.