102 l3 howfundamentals of map.pptx

7/28/2019 102 L3 HowFundamentals of map.pptx

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Fundamentals of Maps

DR.Mukta Girdhar


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What is a Map

Map is usually a two dimensionalrepresentation (eg a flat piece of paper) ofa three dimensional object (eg the Earth)

occasionally it may be a three dimensionalobject (eg a globe)

Maps are drawn to a scale

Maps generally have a reference system


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Five steps fro producing Maps


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Reference System:- Latitude & Longitude, Grid


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Latitude

The first convention to be developed waslatitude. This is based on long termastronomical observations about how thesun is perceived to move across thesurface of the Earth.

These observations also developed theconventions that the sun:

rises in the east and sets in the west


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line around the centre of the Earth would becalled the Equator. This would be numbered aszero degrees (0) of latitude. From the Equatora series of parallel lines were recognised withthe most northern and southern points beingcalled the North Pole and South Pole. Thesewould be numbered as 90 degrees North and

South respectively (90N and 90S).


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Longitude Series of radiating lines which run vertically

around the Earth. They connected at both ends

ie at the North Pole and the South Pole. As aresult of this, a series of slices much like slicesof an orange are created. These are pointed attheir ends and broadest in the middle.

It was agreed that a primary line of longitudeshould be identified and that this should bezero degrees (0) of longitude.


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Add Two Together


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Datum

How to transfer co-ordinate system onto the surface of the earth.


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Measurement system

Measurement system which is usedcalculate the coordinates of pointson the surface of the Earth.


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Projection

which allows the coordinates which havebeen calculated using a measuringsystem, to be displayed on a flat piece ofpaper.


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Different Earth Image


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Distortions

The direction between a featureand surrounding features

The distance between a featureand surrounding features

The shape of any feature

The size of any feature


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Block of 1x1


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Distortion


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Datum

A datum is asystem whichallows the location

of latitudes andlongitudes (andheights) to be

identified onto thesurface of theEarth


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About the Geometry of Datums

In order to calculate wherelatitudes and longitudes occur

on the surface of the Earth anumber of fundamentalgeometric concepts and

practices need to be applied.


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The Earth as a Sphere

In this calculation theEarth is viewed as beingan evenly round ball.

This is called a Sphere.

From an imaginary centreof the Earth, calculationsare made from the centreof the Earth to the surface

of the Earth.


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The Earth as an Ellipsoid (orSpheroid)

However, the Earth is notevenly round - it is in factwider around the Equatorthan it is between the

North and South Poles. This is called an Ellipsoid

(or a Spheroid).


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The Earths True Shape - ItsTerrain

Earth isnt just ocean (Mean SeaLevel). Much of the land massesare well above the sea level (egMount Everest is over 8,000 metresabove Mean Sea Level), while in the

ocean it is well below sea level (egthe Mariana Trench is over 10,000metres below Mean Sea Level.


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The Earth as a Geoid

The Earth in realityis a very misshapenobject. This is

called a Geoid.

The Earths Geoid isregarded as being

equal to Mean SeaLevel.


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Relationship Between Four


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Geo Centric Datum


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Projection

A projection is aprocess which uses thelatitude and longitudewhich has already been

drawn on the surface ofthe Earth using a datum,to then be drawn onto aflat piece of paper -

called a map.


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Projection

Basic Type: depends on thecharacteristic that is preserved

Basic Technique: depends on the

method used to project features ontoa flat surface


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Basic Projection Type

Equal-Areacorrectly shows the size of a feature

Conformal

correctly shows the shape of features (A map can not be both equal-area or conformal it can only be one; or the other; or neither.)

Equidistantcorrectly shows the distance between two features

True Directioncorrectly shows the direction between two features


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Basic Projection Techniques

azimuthal the imaginary piece of paper is flatthis is usually used over Polar areas

conical the imaginary piece of paper is rolled into acone this is usually used in mid-latitude areas(approximately 20 60 North and South)

cylindrical the imaginary piece of paper is rolled intoa cylinder this is usually used over Equatorial areas or forWorld Maps


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Azimuthal

the imaginary piece of paper is flatthis is usually used over Polar areas

These projections:

have distortions increasing away from the central point

have very small distortions near the centre point (the touchpoint of the paper)

compass direction is only correct from the centre point toanother feature not between other features

are not usually used near the Equator, because other projections

better represent the features in this area.
http://www.icsm.gov.au/mapping/coordinates.htmlhttp://www.icsm.gov.au/mapping/coordinates.html


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Azimuthal


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Circles are longitude


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Conical Projections


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These projections:

are fan shaped when used to map large areas

have distortions increasing away from the central

circular line (the touch point of the paper) have very small distortions along the central

circular line (the touch point of the paper)

shapes are shown correctly, but size is distorted

usually have lines of longitude fanning out fromeach other and have lines of latitude as equallyspaced open concentric circles


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2-D Dimension


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Cylindrical / Mercator Projection


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These projections usually:

are rectangular or oval shaped but this projection

technique is very variable in its shape have lines of longitude and latitude at right-angles to

each other

have distortions increasing towards away from the

central circular line (the touch point of the paper) have very small distortions along the central circular

line (the touch point of the paper)

show shapes correctly, but size is distorted.


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Psudo Cylindrical or RobinsonProjection


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Universal Transverse MercatorSystem (UTM)

In 1947 the North Atlantic Treaty Organisation (NATO)developed the Universal Transverse Mercator coordinatesystem (generally simply called UTM)

Regular grid system which covered the entire Surface of theEarth. For low to mid-latitudes (0 to 80 North and South)the IMW established a grid system that was 6 of longitudewide and 4 of latitude high.

locations, shapes and sizes and directions between allfeatures are very accurate. Directions are not perfect.

A i l b f h M i h


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A particular subset of the transverse Mercator is theUniversal Transverse Mercator (UTM) which was adoptedoriginally by the US Army for large-scale military maps. Inthe UTM system, the globe is divided into 60 zones

between 84 S and 84 N, most of which are 6 wide. EachUTM zone has its own central meridian and spans 3 westand 3 east from the center of the zone. Note that theposition of the cylinder developable surface is positioned ata different place around the globe for each zone. X- and Y-

coordinates are in meters by convention.


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For zones in the northern hemisphere, the X-origin is a place 500,000 m west of the centralmeridian, and the Y-origin is the Equator. Thefalse easting is used to eliminate negativecoordinates.

For zones in the southern hemisphere, the X

origin is also 500,000 m west of the centralmeridian, but the Y-origin is the South Pole.


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How Do we Locate

Other Way of Locating

A cartographer is a person who creates Maps

A map on a spherical surface is called a globe


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Role of Direction play in finding alocation


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Magnetic Compass


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Directions and Landmarks alone besufficient ?


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Map Scale

2cm to 1K.M

1:10,000

Graphical or linear scale

Distance on the map =2cm =2cm

Distance on the ground 1km 100 000

=1/50,000


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Large scale & Small Scale

Large scale Map shows a small landarea in great details

Small scale map shows less detailsbut larger area


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Measuring Distances on Maps

Measuring straight linesMark the distance on the paper by a pencil

Measure the distance between pencil marks with a scale

Multiply this

Measuring curved linesIn the case of curved lines like rivers, winding roads, or railway lines, a piece ofstring may be used by carefully aligning it along the curved line connecting twopoints. The length of the string may be measured in centimeter using a scale andthen converted in to distances in kilometer.


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Symbology


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Map Features

Point

Line

Polygon shape of area Text


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What are countours

A contour is an imaginary linesdrawn on maps joining the place thathave same heights. Contours are

numbered to indicate their heightabove sea level. On topographicmaps, every fifth line is drawn by a

thick line and is numbered.


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Contours


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Contours


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Where Are we


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There are many different types of maps

General Reference (sometimescalled planimetric maps)

Topographic Maps

Thematic

Navigation Charts

Cadastral Maps and Plans

Meteorological Map

G l R f ( ti


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These are simple maps showingimportant physical (natural and man-made) features in an area. They are

usually easy to read and understand.

G l R f ( ti


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It is colourful

cities are named

major transport routes(highways and railways) are

identified natural features such as rivers,

lakes and mountains arenamed

elevation is shown using asimple colour shading

has themes included eg citypopulation size


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Tourist Map

It is a general referencemap which has beenenhanced for a specific

reason that ofhighlighting places ofinterest that people

might like to visit.


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Street Map

The Street Map is well knownto all maps. Street mapscontain all the elements of ageneral reference map in

that they are a summary ofthe landscape and that theirprimary purpose is to aid inthe discovery of a location.


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Thematic Maps

These are maps which depictinformation on a particulartopic. Weather, population density and

geology maps are examples ofthematic maps.


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Thematic Map

This map oflimestone caves inTasmania


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Topographic Maps

Like the General Reference Map, Topographic Maps are a summary of thelandscape and show important physical (natural and man-made) features in anarea. The primary difference is that they show elevation in detail.

Characteristics of topographic maps include:

they show elevation using countour line

It shows (roads, cities, buildings etc), but may include some thematicinformation such as vegetation or the boundaries of national parks

they are typically produced by government agencies these are often specialistmapping agencies and may have either a civilian or defence purpose

they have very good location reference systems including lattitude andlogitude, but may also have grid lines often have additional information such as

an arrow pointing to North


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Topographic map

Cadastral Plans


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Cadastral Plans


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Navigation Map

This includes information about theseabed depth below the surface ofthe water. The numbers indicateknown depth for an individual spotand the dotted line is an indication oflines of equal depth - generally called

bathymetric contours (or isobars) todistinguish them from land contours


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Air Navigation Chart

air navigation charts areused by fast flyingaircraft which can bevery high above the

land and havesignificant safetyconcerns when landing.


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Series Maps

These maps typicallyhave a constantscale (eg 1:100,000)

and join together ina regular fashionsuch that a largearea is continuously

mapped


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CONTENTS

Introduction to GIS

Components of GIS

GIS datasets, Spatial and Non Spatial

Raster and Vector

GIS functions


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WHAT IS GIS?

GIS is a system of hardware, software,data and personnel to efficiently capture,

store, update, manipulate, analyze anddisplay all forms of geographically

referenced information.


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Cartographic Display System

Map digitizing system

Database management system

Image processing system

Statistical analysis system

Global positioning system

A geographic information system is atechnology assisted by several systems for theacquisition, storage, analysis and

COMPONENTS OF GIS


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COMPONENTS OF GIS

Hardware Software Data People Application/

procedures


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THE QUESTIONS THAT A GIS CAN ANSWER

What is at......? (Location related question ; whatexists at a particular location)

Where is it.....? (Conditional question ; which locationssatisfy certain conditions)

How has it changed........? (Trendy question ; identifiesgeographic occurrence or trends that have changedor in the process of changing)

Which data are related ........? (Relational question :analyzes the spatial relationship between objects of

geographic features) What if.......? (Model based question ; computers and

displays an optimum path, a suitable land, risky areaagainst disasters etc. based on model)


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In order to meet the above requirements,the following functions are necessary for GIS

data acquisition and pre-processing

data base management and retrieval spatial measurement and analysis

graphic output and visualization


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FUCTIONS OF GIS

DATA CAPTURE: inputting geographic and tabular(attribute) data

STORAGE: two basic data models for geographic datastorage. Vector and raster.

QUERYING :finding specific features based on thelocation or attribute value

ANALYSIS: interaction of spatial relationship betweenmultiple datasets

DISPLAY: visualizing the geographic features using avariety of symbology

OUTPUT: display results in a variety of formats, such

as maps, reports and graphs.

HARDWARE & SOFTWARE


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HARDWARE & SOFTWARE

Hardware is the computer on which a GIS operates.GIS software provides the functions and tools needed to

store, analyze, and display geographic information.

Key software components are:-

Tools for the input and manipulation ofgeographic informationA database management system (DBMS)

Tools that support geographic query, analysis,and visualizationA graphical user interface (GUI) for easy access

to tools


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SOFTWARES

There are many GIS software companies inthe market

Two types mainly

Raster (Image Processing) and Vector butalmost all modern GIS software are capable tohandle both.

Most commonly used GIS /RS Softwares

ArcGIS (ESRI), MapInfo, Geomedia, Gram++,IRIDISI, ERDAS IMAGINE, ER Mapper, ENVI,ILWIS, GRASS , Q-GISetc.

DATA SETS


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DATA SETS

SPATIAL

Spatial data is represented in the form of xand y coordinates.

NON SPATIAL

Non Spatial data can be any other relevantdata related to the spatial feature. Exampleis Demographic, socioeconomic data etc.

RASTER AND VECTOR


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RASTER AND VECTOR

DATA CAPTURE


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Click to edit Master title style

manual digitizingand scanning ofanalogue maps

image data input(Satellite imageries/aerial photo)

Global PositioningSystems (GPS)

Transfer of datafrom existing digitalsources.

DATA CAPTURE

DATA STORAGE RASTER AND


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VECTOR DATA is captured in GISthrough digitization.

Mainly three types

Point: (e.g. rain gauge

stations, Police Stations, FireStations etc)

Line: ( Roads, railway lines,Canals, tectonic features likefaults etc)

Polygons: Administrativeboundaries, land use- landcover maps, water bodies,geology etc)

DATA STORAGE RASTER AND

VECTOR MODELS


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RASTER DATA:

Scanned images

Satellite data

NON SPATIAL DATA: Attribute data (manual data entry) Linking it to existing databases in Access,

Oracle or SQL Server


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PEOPLE

GIS technology is of limited value withoutpeople who manage the system for applying itto real world problems.

Designers or programmers - To develop thesystem as per requirements

Operators To enter and update the GISdatabase and maps

Specialized professionals Meteorologist,urban planners, geologists, emergencymanagers, agronomists etc.

PROCEDURES


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PROCEDURES

Successful GIS operates as perrequirements of the users.

Standard procedures common to all.

Can be customized as per theirindividual needs and requirements.

e.g. HAZUS, RADIUS,HEC RAS, SHAKEetc


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THANKS


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102 l3 howfundamentals of map.pptx

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