TUTORIAL 1 - MAP PROJECTION (COLOR).pdf

17/11/2014

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By :

Dr. Izham Mohamad Yusoff

School of Distance Education,

Universiti Sains Malaysia, Minden,

11800 Penang.

VIDEO CONFERENCE 1 :

MAP PROJECTIONS

JMG 213E/4 :

TECHNIQUES IN GEOGRAPHY

JMG 213E/4 - THE OBJECTIVES

To provide Geographical skills.

Read, analyze, interpret and producing maps.

To locate and differentiate elements of the Earths surface.

Interpret topographic maps where appropriate to the optional themes.

JMG 213E/4 ASSIGNMENT

(DUE DATE : 13th MARCH 2015)

To what extend does GIS benefits the contribution of

Cartography, Remote Sensing and Aerial Photogrammetry

towards producing high quality maps and its interpretations in

Malaysia? State your reason and examples based on (1) one of

the sub-topics below :

1. Climate changes 3. Town Planning

2. Transportation 4. Agricultural

Your assignment must be organized based on the following

sub-sections :

1. Introduction 5. Analysis

2. Study Area 6. Conclusions

3. Literature Review 7. References

4. Methodology (15-20 PAGES)

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JMG 213E/4 - ASSESSMENT

1. The Final Examination (60%)

2. The graded assignments (20%)

3. Continuous Assessment/Test (10%)

4. Practical during intensive course (10%)

(3) and (4) during Intensive Course in USM.

Total : 100%

JMG 213E/4 TOPIC COORDINATOR

Video

Conference

Discussion Topic Topic Coordinator

1

2

3

4

5

6

Map projections

Terrain representation and

contour interpretation

Maps and graphs

Airphoto interpretation

Geographic Information

Systems Revision (VC1 to VC5)

Dr Izham

PM Dr Main

PM Dr Main

PM Dr Main

Dr Izham

Dr Izham

CONTENTS

WHAT AND WHY MAPS

PROJECTION SURFACES

GNOMONIC, STEREOGRAPHIC AND ORTHOGRAPHIC POSITIONS

ORIENTATION OF A PROJECTION SURFACE

GLOBE CHARACTERISTICS

PROJECTION SELECTION AND EFFECTS

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WHAT AND WHY MAPS?

Cartography : The art, science and technology of producing maps.

Map : Abstract representation of the features that occur on or near the surface of the Earth.

(i.e. topographic maps, weather map, geological maps,

thematic maps, chain maps, cadastral maps).

Medium of providing spatial information via GIS (captured from remote sensing imagery, aerial photogrammetry, (Light

Detection and Ranging LiDAR), Unmanned Aerial Vehicle -

UAV).

Why maps? : Effective devices for communicating and recording information about the environment.

Clay tablet map 2200 B.C Northern Mesopotamia

WHAT AND WHY MAPS?...cont


Babylonian clay tablet world map, 600 B.C.

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The map we practices today :

Map reading? Analysis? Interpretation?


Google Earth / Google Map:


Global Positioning System within mobile phone :

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Car Navigation System :

What is the main

component of a map?

Reference system

Legends

Scale

Texture / colouring

Symbolization

Generalization

Metadata

WHAT AND WHY MAPS

PROJECTION SURFACES





PROJECTION SURFACES

A mathematical model for conversion of locations from 3D earth surface to a 2D map representation.

This conversion necessarily distorts some aspect of the earth's surface, such as area, shape, distance or direction.

Every projection has its own set of advantages and disadvantages.

There is no "best" projection.

Some distortions of conformality (shape), scale, distance, direction, and area always result from this processes.

MAP PROJECTIONS

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PROJECTION SURFACES>cont

Some projections minimize distortions in some of these properties at the expense of maximizing errors in others.

Some projection are attempts to only moderately distort all of these properties.

The mapmaker must select the one best suited to the needs, reducing distortion of the most important features.

Mapmakers and mathematicians have devised almost limitless ways to project the image of the globe onto a flat surface

(paper).

MAP PROJECTION...cont


WHY MAP PROJECTION?


Some projections minimize distortions in some of these properties at the expense of maximizing errors in others.

Problem of mapping 3-D coordinates related to a particular datum on a flat surface.

Impossible to convert spheroid into flat plane withoutdistortions map projections.

Assuming : Earth is spherical (where by Earth is ellipsoidal). Why??

WHY MAP PROJECTION...cont

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TYPES OF MAP PROJECTION

There are 3 types :

a) Cylindrical

b) Conical

c) Azimuthal @ Zenithal

Divided into 3 aspects :

a) Equator

b) Transverse

c) Oblique


CYLINDRICAL

Cylinder that has its entire circumference tangent to the Earths surface along a great circle (e.g. equator).

Tangent to the globe at the equator.

No distortions at the equator but it increases moving North or South.

Nice rectangular grid.

Example : Mercator Projection (1569), Transverse Mercator Projection (Lambert 1772).


EQUATOR TRANSVERSE

OBLIQUE

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Mercator Projection (1569)

-Directions are true along straight line of any twopoints, Distances are true only along equator, andreasonable correct within 15 of equator, in secantmodel, distance along two parallels are correct inscale instead of the Equator. Areas and shapes oflarge area are distorted. Distortion increases awayfrom Equator and is extreme in polar regions.However, map is conformal in that angles andshapes within any small area is essentially true.

-Used for navigation or maps of equatorial regions.

Transverse Mercator Projection (Lambert 1772)

- Distances are true only along the central meridianselected by the mapmaker or else along two linesparallel to it, but all distances, directions, shapes,and areas are reasonably accurate within 15 ofthe central meridian. Distortion of distances,directions, and size of areas increases rapidlyoutside the 15 band. Because the map isconformal, however, shapes and angles within anysmall area (such as that shown by a USGStopographic map) are essentially true.

- Used for many USGS 1:24,000 to 1:250,000 map


CONICAL

One or more cones tangent to one or more parallels.

Best for mid-latitudes in an E-W direction (U.S.).

A straight line is almost a perfect great circle route (airplanes use this).

Can be conformal or equivalent.

Example : Lambert Conformal Conic Projection.


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Albers Equal-Area Conic Projection (1805)

- All areas on the map are proportional to thesame areas on the Earth. Directions arereasonably accurate in limited regions. Distancesare true on both standard parallels. Maximumscale error is 1 1/4% on map of conterminousStates with standard parallels of 29 1/2N and 451/2N. Scale true only along standard parallels

- Used for maps showing the conterminous UnitedStated.

Lambert Conformal Conic Projection (1772)

- Distances true only along standard parallels;reasonably accurate elsewhere in limited regions.Directions reasonably accurate. Distortion ofshapes and areas minimal at, but increases awayfrom standard parallels. Shapes on large-scalemaps of small areas essentially true Used formaps of North America. USGS Base Maps for 48conterminous States with standard parallels 33 N,and 45 N (maximum scale error 2 %). for TOPOmaps, standard parallels vary.

- Used for many topographic maps and for StateBase Map series.

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AZIMUTHAL @ ZENITHAL

Plane is tangent to the globe at some point N or S of the equator or one point on the equator.

No distortion at the point of tangency but it increases moving away.

All directions from the center are accurate. It is like a view from space. Can only see half the world at once.

All great circles passing through the point of tangency appear as straight lines.


Example : Polar projections (i.e. Lambert Azimuthal, Stereographic, Gnomonic).


Stereographic Projection

- Directions true only from center point of projection. Scaleincreases away from center point. Any straight line through centerpoint is a great circle. Distortion of areas and large shapesincreases away from center point.

- Used for maps of Antarctica and Arctic, for TOPO maps andnavigating in latitudes above 80, and for some geophysical mapsand NEXRAD precipitation products.

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WHAT AND WHY MAPS

PROJECTION SURFACES





GNOMONIC, STEREOGRAPHIC AND

ORTHOGRAPHIC POSITIONS

THE PERSPECTIVES :

A gnomonic map projection displays all great circles as straight lines.

Gnomonic projections : place the light source at the centre of the globe.


ORTHOGRAPHIC POSITIONS>cont

Stereographic projection is a particular mapping (function) that projects a sphere onto a plane.

Stereographic projections : place the light source at the antipode of the point of tangency.

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ORTHOGRAPHIC POSITIONS>cont

Orthographic projection is a perspective (or azimuthal) projection, in which the sphere is projected onto a tangent

plane or secant plane.

Orthographic projections - place the light source an infinite distance from the point of tangency, resulting in parallel light

rays.

WHAT AND WHY MAPS

PROJECTION SURFACES





ORIENTATION OF A PROJECTION

SURFACE

Cylindrical

Transverse Cylindrical

Oblique Cylindrical

Secant Cylindrical

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ORIENTATION OF A PROJECTION

SURFACE>cont

Conical Secant Conical Planar Secant Planar

WHAT AND WHY MAPS

PROJECTION SURFACES





GLOBE CHARACTERISTICS>cont

Angles on a conformal map are the same as measured on the Earths surface. Area and distance of square are distorted.

Meridians intersect parallels at right angles.

CONFORMAL MAP PROJECTION

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Application : Designing topographical maps

Projection Examples :

- Mercator - rhumb lines are represented by straight segments

Stereographic - shape of circles is conserved

- Roussilhe

- Lambert conformal conic

- Quincuncial map

- Adams hemisphere-in-a-square projection

- Guyou hemisphere-in-a-square projection

Malaysia : Rectified Skewed Orthomorphic projection

is used for developing national topographical maps.

CONFORMAL MAP PROJECTION


TOPOGRAPHIC MAPS


Scale factor along a meridian is equal to 1.

Shape and area of square are distorted.

EQUIDISTANT MAP PROJECTION

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Applications : Designing cadastral maps.


- Equirectangular - distances along meridians are conserved.

- Azimuthal equidistant - distances along great circles radiating

from centre are conserved.

- Equidistant conic.

- Sinusoidal - distances along parallels are conserved

Malaysia : Cassini-Soldner projection is used for developing

cadastral maps.

EQUIDISTANT MAP PROJECTION


CADASTRAL MAPS


Equal areas are represented by the same map area regardless of where they occur.

Shape and distance of sphere are distorted.

EQUAL-AREA MAP PROJECTION

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Applications : Designing thematic maps (demographic maps, land use, rainfall).


- Gall orthographic (also known as GallPeters, or Peters,

projection)

- Albers conic

- Lambert azimuthal equal-area

- Lambert cylindrical equal-area

- Mollweide

- Hammer

- Sinusoidal

EQUAL-AREA MAP PROJECTION


THEMATIC MAPS

WHAT AND WHY MAPS

PROJECTION SURFACES





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PROJECTION SELECTION & EFFECTS

PROJECTION SELECTION

Map purpose :

- For distribution maps: equal area.

- For navigation : projections that show azimuths or

angles properly.

Size of area :

- Some projections are better suited for East-West

extent, others for North-South.

- For small areas the projection is relatively

unimportant (< 10 km2).

- For large areas the projection is very important

(> 10 km2).


PROJECTION SELECTION

No flat map can be both equivalent and conformal.

The various methods of preparing a 2D plane from

the Earths surface are

critical to the accessibility

and presentation of GIS.

Map projection is not an accurate portrayal of the

globe because 2D plane

cannot represent the large portions of the curve-linear surface

accurately.


THE RIGHT CHOICE

Conic projections for mid-latitudes :- True along some parallel between the poles and

equator.

Cylindrical for equatorial regions :- True at the equator and distortion increases towards

the poles.

Azimuthal for poles :- True only at their center point but distortion is

generally worst at the edges.

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PROJECTION SELECTION &

EFFECTS>cont

PROJECTION EFFECTS

Mercator projection:

Maintains shape and direction.

Sinusoidal and Equal-Area

Cylindrical projections:

Both maintain area, but look

quite different from each other.

Robinson projection :

Does not enforce any specific

properties but is widely used

because it makes the earths

surface and its features look

right.

ANY QUERIES?

Room No :

01,

Cabin B, Behind Student Main Hall,

USM Main Campus, Penang.

E-mail :

[email protected]

TUTORIAL 1 - MAP PROJECTION (COLOR).pdf

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