Components of gis

Components of geographical information system(GIS)

1. Seminar on COMPONENTS OF GIS (Geographic Information System)

2. CONTENTS INTRODUCTION DEFINITION OF GIS COMPONENTS OF GIS AREA OF GIS APPLICATIONS CONCLUSION REFERENCE

3. INTRODUCTION We use a word processor to write documents and deal with words on a computer, similarly we can use a GIS application to deal with spatial information on a computer. GIS stands for ‘Geographic Information System’. A Geographic Information System (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.

4. GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts. A GIS helps you answer questions and solve problems by looking at your data in a way that is quickly understood and easily shared.

5. Components of GIS The major components of GIS is Hardware, Software, Data, People, Procedure Network

6. Hardware The computer or Central Processing Unit is the general hardware component of the GIS. It is attached to a disk drive storage unit, used for storing data and program. Devices like digitizer, scanner are used for converting the data, which is available in the form of maps and documents, into digital form and send them to computer. Display device or a plotter is used which presents the result of the data processing .

7. A tape device is used to store data or program on magnetic tape.

8. Software The GIS software includes the programs and the user interface for driving the hardware. GIS software is essential to generate, store, analyze, manipulate and display geographic information or data. A good GIS software requires user friendliness, functionalities, compatibilities, updatability, documentation, cost effectiveness. The basic functions GIS software should offer can be grouped into data capture, data management, data analysis and representation:

9. Data capture - no data, no GIS. Data capture functionality could either be the importing of digital data from a disk, network or database, or digitizing it through the use of peripheral devices. Data management - quality is essential. One step beyond data capture is data editing and maintenance. Editing involves functions such as adding, duplicating and deleting spatial and attribute data as well as creation and management of metadata. Using tools to detect errors and to perform transformations is another aspect of data management.

10. Data analysis - ask questions. A GIS is typically used to answer questions related to space. For the purpose of finding an answer, a GIS should not only offer tools to query and retrieve data, but also functions for data integration and modeling. Visualization - make it visible. Any analysis of data is only useful if the final output is also understood by the intended recipient. A GIS offers tools to present data in various ways, ranging from displaying tabular information, over graph/chart production, to printing maps. Some GIS offer advanced visualization beyond two dimensions, such as digital elevation model (DEM) or digital movie files. Output can also be shared by storing it on a disk or a web server, which allows for dynamic views of the data.

11. Aside from these basic functions, a GIS should also offer ways for customizing and creating new tools and applications according to your needs. Depending on the software, this can either be done through well known programming or scripting languages such as Visual Basic or Python, or through a programming language specifically provided by the application. The following is a list of GIS software producers and their main products. Environmental Systems Research Institute ( ESRI ): Arc Info, Arc View. Arc GIS . Autodesk: AutoCAD Map

12. International Institute for Aerospace Survey and Earth Sciences: ILWIS MapInfo Corporation: MapInfo. PCI Geomatics : PA MAP Telogis : Geobase

13. DATA The most important component of a GIS is the data. Geographic data and related tabular data can be collected in-house, compiled to custom specifications and requirements, or occasionally purchased from a commercial data provider. A GIS can integrate spatial data with other existing data resources, often stored in a corporate DBMS. The integration of spatial data, and tabular data stored in a DBMS is a key functionality afforded by GIS.

14. The ability of GIS to handle and process geographically referenced data, distinguish GIS from other Information systems. Geographically referenced data describe both the location and characteristics of spatial feature on earth surface. GIS therefore involves two geographic data components. 1. Spatial Data : Spatial data describes the absolute and relative location of geographic feature. It relate to the geometry of a spatial feature. 2.Attribute Data: Attribute data describes characteristics of spatial features. Attribute data are often referred to as tabular data. It gives information about the spatial features.

15. Spatial Data RASTER data type consists of rows and columns of cells, with each cell storing a single value.

16. The vector data model uses points and their x-, y- coordinates to construct spatial features of points, lines and areas. Vector based features are treated as discrete objects over the space. Points Entities : - Points defines discrete location of geographic feature too small to be depicted as lines or areas, such as well location, telephone pole etc. Point can also represent location that have no area such mountain peak. Line Entities : - Line entities can be defined as all features built up of straight-line segments made up of two or more coordinates. The simplest line required the storage of a begin point and an end point (two XY coordinate points) plus a possible records indicating the display symbol to be used. Area Entities : - Areas of polygons can be represented in various ways in a vector database. The simplest way to represents a polygon is an extensions of the simple chain, i.e. to represents each polygon as a set of XY coordinates on the boundary. Areas are closed figures that represent shape and location of homogeneous feature such as states, soil types, land use zones.

17. ATTRIBUTE DATA Georelational data model links spatial data and attribute data by id. Attribute data stored in feature attribute table which contains the id. Row is called a record, column is called a field or an item.

18. Procedure & Method Procedure, more related to the management aspect of GIS, is referred to lines of reporting, control points, and other mechanism for ensuring the high quality of GIS. The procedures used to input, analyze, and query data determine the quality and validity of the final product. The right method is a key for successful operation of GIS technology. The well-designed implementation plan and business rules are unique to each organization.

19. Topological Relationships between Spatial Objects In practical applications of GIS, all possible relationships in spatial data should be used logically with more complicated data structures. The following topology relationships are commonly defined. a. Point-Pont Relationship "is within" : within a certain distance "is nearest to" : nearest to a certain point b. Point-Line Relationships "on line" : a point on a line "is nearest to" : a point nearest to a line c. Point-area Relationships "is contained in’’ : a point in an area "on border of area" : a point on border of an area d. Line-Line Relationships "intersects" : two lines intersect "crosses" : two lines cross without an intersect "flow into" : a stream flows into the river e. Line-Area Relationship "intersects" : a line intersects an area "borders" : a line is a part of border of an area f. Area-Area Relationships "overlaps" : two areas overlap "is within" : an island within an area "is adjacent to" : two area share a common boundary

20. Database Models A database model is a type of data model that determines the logical structure of a database and fundamentally determines in which manner data can be stored, organized, and manipulated. The most popular example of a database model is the relational model, which uses a table-based format.

21. In a Hierarchical model, data is organized into a tree-like structure, implying a single parent for each record. This structure allows one-to-many relationship between two types of data. The network model expands upon the hierarchical structure, allowing many-to-many relationships in a tree-like structure that allows multiple parents. A flat file database describes any of various means to encode a database model(most commonly a table) as a single file. A flat file can be a plain text file or a binary file. There are usually no structural relationships between the records. In the relational model of a database, all data is represented in terms of tuples , grouped into relations. A database organized in terms of the relational model is a relational database.

22. Thematic Data Modeling The real world entities are so complex that they should be classified into object classes with some similarity through thematic data modeling in a spatial database. The objects in a spatial database are defined as representations of real world entities with associated attributes. Generally, geospatial data have three major components; position, attributes and time. Attributes are often termed "thematic data" or "non-spatial data", that are linked with spatial data or geometric data. An attribute has a defined characteristic of entity in the real world. Attribute can be categorized as normal, ordinal, numerical, conditional and other characteristics. Attribute values are often listed in attribute tables which will establish relationships between the attributes and spatial data such as point, line and area objects, and also among the attributes.

23. Spatial objects grouped in layers

24. Data Structure for Continuous Surface Model In GIS, continuous surface such as terrain surface, meteorological observation (rain fall, temperature, pressure etc.) population density and so on should be modeled. As sampling points are observed at discrete interval, a surface model to present the three dimensional shape ; z = f (x, y) should be built to allow the interpolation of value at arbitrary points of interest. Usually the following four types of sampling point structure are modeled into DEM. Grid at regular intervals : Bi-linear surface with four points or bi-cubic surface with sixteen points is commonly used Random points : Triangulated irregular network (TIN) is commonly used. Interpolation by weighted polynomials is also used.

25. Data Structure for Continuous Surface Model Contour lines : Interpolation based on proportional distance between adjacent contours is used. TIN is also used. Profile : Profiles are observed perpendicular to an alignment or a curve such as high ways. In case the alignment is a straight line, grid points will be interpolated. In case the alignment is a curve, TIN will be generated.

26. People GIS technology is of limited value without the people who manage the system and develop plans for applying it to real world problems. GIS users range from technical specialists who design and maintain the system to those who use it to help them perform their everyday work. The identification of GIS specialists versus end users is often critical to the proper implementation of GIS technology.

27. NETWORK Network allows rapid communication and sharing digital information. The internet has proven very popular as a vehicle for delivering GIS applications. 

28. Area of GIS Applications Major areas of GIS application can be grouped into five categories as follows. Facilities Management Large scale and precise maps and network analysis are used mainly for utility management. Environment and Natural Resources Management Medium or small scale maps and overlay techniques in combination with aerial photographs and satellite images are used for management of natural resources and environmental impact analysis. Street Network Large or medium scale maps and spatial analysis are used for vehicle routing, locating house and streets etc. Planning and Engineering Large or medium scale maps and engineering models are used mainly in civil engineering. Land Information System Large scale cadastre maps or land parcel maps and spatial analysis are used for cadastre administration, taxation etc.

29. CONCLUSION Now a days GIS got very much scope in all most all the fields such as Mapping to identify the borders of cities , districts , countries etc. It is also helpful in finding the populations of the areas It is also essential to study geological settings of the area by digitizing maps.

30. GIS components is useful to display spatial patterns hidden in table and database. It allows to create detailed maps. Describes the functional basis of GIS and appreciate the potential users in GIS For many years, though GIS has been considered to be too difficult, expensive, and proprietary. The advent of graphical user interface (GUI), powerful and affordable hardware and software, and public digital data has broadened the range of GIS application and brought GIS to mainstream use.

31. REFERENCE M.Anji Reddy; Remote sensing and G.I.S & Fundamentals of G.I.S(2000); pp:122-141 Debashis Chakra borty-Rabi N.Sahoo; Fundamentals of GIS(2007)by: -pp 1-22. David J Buckley; An Introduction to Geographic Information Systems- pp1-72 Shahab fazal; G.I.S Basics(2008) pp:13-21 Websites http://en.wikipedia.org/wiki/Geographic_information_system http://giswin.geo.tsukuba.ac.jp/sis/tutorial/Fundamentals_of_GIS_Estoque.pdf http://wtlab.iis.u-tokyo.ac.jp/~wataru/lecture/rsgis/giswb/vol1/contents.htm

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