GGeographical Information System

GGeographical Information System

o A set of tools for Collecting Storing Retrieving Transforming and Display Of Spatial Data from the Real World

WWhat is a GIS? 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.

IIntroduction

o Use of Information Technology has enabled a new dimension in the day-to-day functioning of human life in the new Millennium.

o Planning is the basis for Development, which has a multiple effect on the utilization of all the resources and infrastructure facilities.

o Making the Governmental bodies effective, needs a tool or technology to enable and sensitize the managers or administrators at different levels.

o GIS ( Geographical Information Systems) is one such famous IT application tool which can provide best decision support to bridge the gap between the requirements and the reality.

o With the exponential growth in IT application and the digital literacy all over the world, and GIS being the most advantageous visual dimension of data base, the potential for GIS application is unlimited .

RRemote Sensing

o Real information of geography at real times through Satellites. oStarted in 1970’s with the prime objective of obtaining Information about Natural Resources.

oLANDSAT – 1….6 was the first Satellite series launched in the World by Europian Countries.

oIndian Space Programme (Dept. of Space) was set up in 1972.

oIRS - IC , IRS - ID and IRS - P4 are the latest and currently used Indian Remote Sensing Satellites .

oThe maximum resolution available from IRS data is 5.8 meters.

oIKONOS data- 1 metre resolution

oDigital Globe- 0.5 metres resolution

AA picture is worth a thousand Words.

o Vision is the most advanced of human senses so it is natural that images play most important role in human perception.

o Improvement of pictorial information for human interpretation.

o Ease of storage transmission and representation for machine/human perception.

DDigital Image

o A digital image is obtained after digitization o Sampling + Quantization Digitization

o Sampling = Spatial sampling o Quantization = finite precision representation of

intensity values o Each sample is called a pixel (picture element)

IImage – A rectangular array of pixel

VVisual Image Interpretation

Advantages :- o Human Knowledge and Experience o Parallel Processing o Minimum resources required

Disadvantages :- o Subjective o Inefficient in storage and transmission o No enhancements or image manipulations o No direct use in GIS o Only fixed band combination

DDigital Image Processing

Advantages :- o Objective o Easy in storage and transmission o Direct use in GIS o Enhancements and image manipulations o Various band combinations for MS sensors o Efficient to detect tonal variations o Good for large area mapping

Disadvantages:- o Difficult to implement Human Expertise o Lot of resources required

o Pixel to Ground Resolution o Multi-Spectral Image o Multi-Temporal Image o Pseudo Colour Image o True & False Colour Composite

IImportant Terms

SSpatial Resolutions

Sensor: WiFS Resolution:180m

Sensor: LISS-III Resolution: 24m

Sensor: LISS-IV Resolution:5m

RED

BLUE

GREEN

FCC

MMulti Spectral Data

MMulti Spectral Data

Wheat

Mustard

MMulti Temporal Images (1998-1999)

PPseudo Colour Image

FFalse and True Color Composites

False Colour Composite True Colour Composite

NIR Red Green Red Green Blue

+

=

PAN PAN LISS

MERGED

DData Fusion

High Spatial resolution High Spectral resolution

GGIS 1. Stands for Geographical Information System

2. Is a decision making tool

3. Readily gives a spatial reference of data (Links data with the related area and thus gives area specific details)

4. A software tool which has all utilities like search, analysis, reproduction etc.

GGIS Areas Geo Sciences Engineering Transportation Natural resources Environment Planning Administration Management Business

Remote Sensing Image processing Urbun & Rural Development Floods , Disasters Oil exploration Mines Surveys Watershed management Tourism Communications

SSoftware GIS Image Processing

� ARC INFO � ArcView � MapInfo � MGE � Geomedia � Geoconcept � WINGIS � Microstation � AutoCAD

� ERDAS � ER Mapper � ILWIS � ENVI � PCI � ArcView image analysis � TNTMIPS � Ecognition

MMajor Services in RS & GIS

o GIS Application Software development o Remote Sensing Application Projects o Thematic Mapping o Digital Image Processing Services o Engineering Application Software solutions o Data Conversions o Complete GIS Implementation o Consultation

DData Structure…. GIS

GRAPHIC ALPHA NUMERIC

VECTOR RASTER

CO-ORDINATE SYSTEM

IMAGE

AREAL PHOTOGRAPH

REMOTE SENSED SCANNED IMMAGES

WWhat Data is in Your GIS?

o What features do you map?

o What attributes do you need to collect data on?

o What attribute values can you give the attribute?

MMaps And Map Elements

o Maps are graphic representation of our perception of the world around us. They represent cartographic interpretation and simplification of reality.

o Maps provide two types of information o Locational information o Spatial Relationships

MMaps contains features such as……… Point, Line, Area and Surface

o Maps contain POINT features, LINE features and AREA features

o Point Features :- wells, control points, sample sites, fire stations

o Line Features :- roads, hydro lines, rivers, contour lines,

o Area Features:-urban areas, water bodies, soil/rock units, forest areas

Point Features o Spatially distributed entities, activities or events o Points have a single geographic coordinate such

as: o Tree o Traffic accident o Lamp post

Line Features

o Spatially distributed entities, activities or events o Lines (Arcs) are a series of geographic coordinates

joined to form a line such as: o Road o Stream o Railway

AArea Features

o Spatially distributed entities, activities or o events o Areas (Polygons) are a series of geographic

coordinates joined together to form a boundary such as: o Lake o Soil types

DATA

ATTRIBUTE DATA

SPATIAL DATA 1.

2.

SPATIAL DATA

Raster

Vector

Data Model And Structure

RASTER MODEL VECTOR MODEL

o Attributes can be numeric or alfanumeric data that is assigned to a point, line or area spatial features

o Example Attributes… Stand ID, Compartment no,Vegetation type,

Name of the Forest Block,Type of Road,VSS code etc.,

AAttribute Data

o Topology - mathematical representation of geographic features(arcs, nodes, polygons and points)

o When topology is built, it creates spatial relationship among the features

o Topology can be very important for certain types of analysis.

TTopology

VVector Data o A vector system usually stores data as coordinates. o For example Each uniform area is surrounded by a set

of straight line segments called vectors. o In a vector based system every point is recorded by a

pair of x and Y coordinates. o Straight line segments called vectors are displayed to

indicate line based data ( roads rivers wells) o The x-y coordinates at the end of each vector can be

digitised and stored. o Most spatial features can be displayed as: - Points-

Line- Polygons

RRaster Data oA grid (or raster) system stores data as a string of characters in which each character represents a location. oThe basic data unit is a cell or Pixel oEach cell/Pixel is assigned only one value oAn array of Pixels form the entity-Point, Line, Area and surface oThe shape and size of the array determines the basic Resolution oPolygons can be formed indicating areas of homogeneous characteristics

WWhy GIS ?

o To inventory and monitor resources o To test the sensitivity of our analysis assumptions o To simulate potential impacts of management

alternatives o To make the map the 2nd time, the 50th time, the

100th time...

UUses of a GIS

o Mapping geographical characteristics for analysis o Modeling alternative processes

for management plans o Managing a utility’s assets o Monitoring changes in environmental factors

Measuring and Integrating the Parts...

Social Factors

Biodiversity

Engineering

Land Use

Environmental Considerations

…Means Seeing the Whole

GIS Integrates All the Parts…to See the Whole!

Homes

School Districts

Streets

Zip Codes

Cities

Counties

TThematic Overlay

1. TOPOGRAPHY 2. BOUNDARIES 3. VILLAGES 4. ROADS

5. DRAINAGE 6. SOILS

ELEVATION

LAND USE

LAKES

VILLAGES

STREETS

SOILS

TThematic Overlay

QQuery and Analysis

Data Query Output

Mandals

3 villages of numbers 8,5and 3 are having population more than 1000 and with out a school.

llsls

Zahirabadd

Sadasivapet

Identify villages where population

is > 1000 but no school

Villages Population

Report

Sanga reddy

n5

3 2

8 7

1 4

Village Buffer 5km

6 2

3

4 5 7

3

8 5

6

TTypical GIS Applications

o Environmental Assessments o Land Information System o Land Use And Thematic Mapping o Health Care, Disease Profile o Forestry And Wild Life Tracking o Waste Land Development o Ground Water Resources Management o Urban And Town Planning o Defenceo Business And Retails

IIndispensability Of GIS

o Though collection of data is difficult once it is collected, it can be stored safely in digital form (in computer) forever without damage, which usually happens to our maps.

o Once if a map is prepared accurately it can be printed in any scale without any redrawing.

o Large scale maps at smaller units level can be joined for creating maps at divisions or district level, very accurately within few minutes.

o Changes can be incorporated very easily in computer and it doesn’t require any redrawing.

o Same map can be generated even after 100s of years later.

o New things can be known after overlay of different themes and a new types of maps can be generated.

o Work can be done faster than manually.

o The work of decision makers and end users will become easier.

WWhat is Photogrammetry?

o Photogrammetry is the art, science and technology of reliable information about physical objects and the environment through processes of recording, measuring and interpreting photographic images, patterns of electromagnetic radiant energy and other phenomenon

o Photos = light o Gramma = something drawn or written o Metron = to measure

SScale variations with flying height

Terrestrial Photograph Vertical Photograph

SSample Photographs

TTHANK YOU