2. Contents
What is GIS?
Components of GIS
GIS Process
Functions of GIS
Applications of GIS
Data Structure
Data File Formats
Map & Map Elements
Data Modelling
GIS Data Sources
Geospatial Analysis
Conclusion
3. What is GIS?
“A system for capturing, storing, checking, integrating, manipulating, analyzing
and displaying data which are spatially referenced to the Earth. This is normally
considered to involve a spatially referenced computer database and appropriate
applications software”
A set of tools for
Collecting
Storing
Manipulating
Retrieving
Transforming and Display of Spatial Data from the Real World
4. GEOGRAPHIC implies that locations of the data items are
known, or can be calculated, in terms of Geographic
coordinates (Latitude, Longitude)
INFORMATION implies that the data in a GIS are organized to
yield useful knowledge, often as colored maps and images, but
also as statistical graphics, tables, and various on-screen
responses to interactive queries
SYSTEM implies that a GIS is made up from several inter-
related and linked components with different functions. Thus,
GIS have functional capabilities for data capture, input,
manipulation, transformation, visualization, combinations,
query, analysis, modelling and output
5. Components of GIS
GIS links locational (spatial) and database (tabular) information and enables a
person to visualize patterns, relationships and trends. The five components of GIS
are as under:
1. Hardware
2. Software
3. Data
4. People
5. Methods
6. Hardware
Systems to support rapid graphic analysis and processing
(CPU, processor, keyboard etc.)
Software
A technology for storing and analyzing location and
attribute data (ArcGIS, Map Info, AutoDesk Map etc.)
Data
Geographical data in form of hardcopy map, digital map,
aerial photos, satellite images, other documents for GIS
operations
Methods
Various procedures including analysis, manipulation, presentation,
visualization, modelling
People
Different user and GIS application experts
7. GIS Process
Links databases and maps
Manages information about places
Helps answer questions such as:
Where is it?
What else is nearby?
Where is the highest concentration
of ‘X’?
Where can I find things with
characteristic ‘Y’?
Where is the closest ‘Z’ to my
location?
8. Functions of GIS
Data Capture
Data Storage & Management
Data Display
Data Editing, Manipulation and Analysis
Presentations & Visualization
9. Applications of GIS
Agriculture Archaeology
Architecture/Landscape Arch.
Business Computer Science
Environmental Science
Engineering
Journalism
Military Science
Natural Resource Management
Geography
Geology
Meteorology
Oceanography
Law Enforcement
Public Health
History
Sociology
Urban/Regional Planning
11. GIS Data Formats (file formats)
Shapefiles
Coverages
TIN (e.g. elevation can be stored as TIN)
◦ Triangulated Irregular Network
Grid (e.g. elevation can be stored as Grid)
Image (e.g. elevation can be stored as image, all remote
sensing images)
Vector data
Raster data
12. Shape Files
Nontopological
Advantages no overhead to process topology
Disadvantages polygons are double digitized, no topologic data
checking
At least 3 files .shp .shx .dbf
13. Coverages
Original ArcInfo Format
Directory With Several Files
Database Files are stored in the Info Directory
Uses Arc Node Topology
Containment (coincident)
Connectivity
Adjacency
14. TIN
A triangulated irregular network (TIN) is a data model
that is used to represent three dimensional objects.
In this case, x,y, and z values represent points.
Using methods of computational geometry, the points
are connected into what is called a triangulation, forming
a network of triangles. The lines of the triangles are called
edges, and the interior area is called a face, or facet.
The illustration shows how we can create a TIN of the terrain
First, a series of elevation points are created
Second, a TIN face is created with the elevation data
Third, the faces are shaded in to give the impression of a 3D surface
16. Map & Map Elements
Maps provide two types of information: Locational Information and Spatial
Relationships
Maps contain POINT features, LINE features and AREA features
Point Features Line Features Area Features
Spatially distributed entities,
activities or events
Points have a single geographic
coordinate such as: Tree, traffic
accident, lamp post
Spatially distributed entities,
activities or events
Lines (Arcs) are a series of
geographic coordinates joined to
form a line such as: Road, stream,
railway
Spatially distributed entities,
activities or o events
Areas (Polygons) are a series of
geographic coordinates joined
together to form a boundary such
as: Lake, soil types
18. GIS Data Sources
Existing data
Digital
Map and Plan
Paper Files
Low Cost
Acquisition
Remote Sensing
Photogrammetry
Field Survey
High Cost
19. Geospatial Analysis
Geography + GIS = Geospatial
An approach to applying statistical methods and other
informational techniques to data which has a geographical or
geospatial aspect
Such analysis would typically employ software capable of geospatial
representation and processing, and apply analytical methods to
terrestrial or geographic datasets, including the use of GIS
20. Operations
Surface analysis
In particular analyzing the properties of physical surfaces, such as gradient,
aspect and visibility, and analyzing surface-like data “fields”
Network analysis
Examining the properties of natural and man-made networks in order to
understand the behavior of flows within and around such networks; and
locational analysis
Geovisualization
The creation and manipulation of images, maps, diagrams, charts, 3D views and
their associated tabular datasets
21. Conclusion
GIS is a broad term that can refer to a number of different
technologies, processes, and methods
It is attached to many operations and has many applications related
to engineering, planning, management, transport/logistics,
insurance, telecommunications, and business
Modern GIS technologies use digital information, for which various
digitized data creation methods are used
Many disciplines benefit from GIS
