Components of gis

Seminar on
COMPONENTS OF GIS
(Geographic Information System)

CONTENTS
• INTRODUCTION
• DEFINITION OF GIS
• COMPONENTS OF GIS
• AREA OF GIS APPLICATIONS
• CONCLUSION
• REFERENCE

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.

 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.

Components of GIS
 The major components of GIS is
◦ Hardware,
◦ Software,
◦ Data,
◦ People,
◦ Procedure
◦ Network

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.

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

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

◦ 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.

 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.

 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

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

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

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.

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

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,

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.

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.

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

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.

 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.

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.

Spatial objects grouped in layers

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.

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.

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.

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

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.

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.

 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.

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_s
ystem
◦ http://giswin.geo.tsukuba.ac.jp/sis/tutorial/Fundament
als_of_GIS_Estoque.pdf
◦ http://wtlab.iis.u-
tokyo.ac.jp/~wataru/lecture/rsgis/giswb/vol1/contents.
htm

Components of gis

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