introduction to gis...introduction to gis dr. m.s. ganesh prasad department of civil engineering the...

Introduction to GIS

Dr. M.S. Ganesh Prasad

Department of Civil Engineering

The National Institute of Engineering, MYSORE

ganeshprasad.nie@gmail.com

9449153758

Geographic Information System (GIS)

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Information System

Geographic Position

So, what is GIS?

A method to Analyze, Manipulate, Visualize and Display Data.

Geographical Data

Where is it? (Spatial)

Geographical coordinates

What is it? (Non-spatial)

Attributes

What is their relation with each other?

Topology

What makes data spatial?

Placename Grid co-ordinate

Postcode

Distance & bearing Description

Latitude / Longitude

Representing Spatial Data

Points - simplest element

Lines (arcs) - set of connected points

Polygons - set of connected lines

We typically represent objects in space as three

distinct spatial elements:

We use these three spatial elements to represent real world features and

attach locational information to them.

Point Features

Spatially distributed entities, activities or events

• Points have a single geographic coordinate such as:

– Tree

– Traffic accident

– Lamp post

Line Features

Spatially distributed entities, activities or events

• Lines (Arcs) are a series of geographic coordinates joined to form a line such as:

– Road

– Stream

– Railway

Area Features Spatially distributed entities, activities or events

• Areas (Polygons) are a series of geographic coordinates joined together to form a boundary such as:

– Lake

– Soil types

Attributes

Description or characteristic of a feature

• Possible attributes for the feature Tree

– Height

– Diameter

– Species

– Condition

– Age

Attribute Values The value given to an attribute

• Possible values for the attributes of a Tree feature

– Height = 15m

– Diameter = 0.75m

– Species = Oak

– Condition = Good

– Age = 8 years

Data Acquisition

• Primary data – Field Surveying: Total Stations, GPS – Photogrammetry: Analogue, Digital – Remote Sensing: Active, Passive

• Secondary data – Raster data capture using scanners – Vector data capture using digitizer

• Data from external sources (CAD files, different data formats etc.)

• Capturing Attribute data (Tables, statistical records, census etc.)

Field Surveying

GPS Satellites

Photogrammetry

Measurement from a distance

Remote Sensing

Data from Maps: Scanners

Data from Maps: Digitizer

Data Storage and Management

• Data Base Management

– Systems – Entry, Editing, Report, Masking

– Retrieval – Query, SQL

• Data Compaction

– Relational Database models

– Object-Oriented Database models

Data Analysis Functions

• Transformation Functions (Map Projection, Vector to Raster & vice versa)

• Classification & measurement functions

• Overlay functions

• Neighborhood functions

• Topographic and interpolation functions

• Proximity functions(Buffering)

• Network functions

• Inter-visibility functions

• And many more ……

Data - Spatial & Tabular

Spatial Data: Any entity that has location and can be shown on a map. E.g., Boundaries of States of India.

Tabular Data: Attributes of the spatial entity. E.g., State wise Per Capita Income.

Some GIS Software

• IDRISI

• ILWIS

• ARC-INFO (ARC-GIS)

• ARC VIEW

• MGE

• GRASS

• GISPAD

To summarise GIS comprises of:

• Data input

• Storage

• Management

• Analysis

• Output

GIS has many applications

• Geosciences (especially geography, ecology, geology, geophysics, geodesy)

• Surveying and cadastral mapping

• Digital topographic and thematic mapping

• City and landscape planning

• Military applications

• Pipeline and route planning, public utilities, facilities management

• Forestry

• Health and Insurance

• Marketing, retailing and many more………

Some current applications of GIS

Agriculture

Monitoring and management from farm to National levels

Archaeology

Site description and scenario evaluation.

Environment

Monitoring, modeling, and management for land degradation;Land evaluation and rural planning; landslides; desertification; Water quality and quantity; plagues; air quantity; weather and climate modeling and prediction.

Epidemiological and Health

Location of disease in relation to environmental factors.

Forestry

Management, planning and optimizing extraction and replanting.

Emergency services Optimizing fire, police and ambulance routing; improved understanding of crime and its location.

Navigation

Air, sea and land.

Marketing

Site location and target groups; optimizing goods delivery.

Real Estate

Legal aspects of the cadastre, property values in relation to location, insurance.

Regional / local Planning

Development of plans, costing, maintenance, management.

Some current applications of GIS

Road and rail

Planning and management.

Site evaluation and Costing

Cut and fill, computing volumes of materials.

Social studies

Analysis of demographic movements and developments.

Tourism

Location and management of facilities and attractions.

Utilities

Location, management, and planning of water, drains, gas, Electricity, telephone, cable services.

Some current applications of GIS

Attribute data of houses:

house number

area of the house

area of the site

site number

type of construction

address

house tax (paid or not)

tax last paid

water tax

number of persons ( male and female )

family income etc…

What difference can GIS make?

Muncipal Uses of GIS

Town planning (and development of civic amenities

like schools, hospitals, fire stations, shopping)

Utility management.

Socio-economic planning (projecting future

population)

Property taxation.

Transportation system and traffic management.

Planning, development and managing the utilities

like water supplies, sewerage system, water supply,

telephone system and power.

Solid waste management etc..