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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)
17/11/2014
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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
WHAT AND WHY MAPS?...cont
Babylonian clay tablet world map, 600 B.C.
17/11/2014
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WHAT AND WHY MAPS?...cont
The map we practices today :
Map reading? Analysis? Interpretation?
WHAT AND WHY MAPS?...cont
Google Earth / Google Map:
WHAT AND WHY MAPS?...cont
Global Positioning System within mobile phone :
17/11/2014
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WHAT AND WHY MAPS?...cont
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
GNOMONIC, STEREOGRAPHIC AND ORTHOGRAPHIC POSITIONS
ORIENTATION OF A PROJECTION SURFACE
GLOBE CHARACTERISTICS
PROJECTION SELECTION AND EFFECTS
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
17/11/2014
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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
PROJECTION SURFACES>cont
WHY MAP PROJECTION?
PROJECTION SURFACES>cont
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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PROJECTION SURFACES>cont
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
PROJECTION SURFACES>cont
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).
PROJECTION SURFACES>cont
EQUATOR TRANSVERSE
OBLIQUE
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PROJECTION SURFACES>cont
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
PROJECTION SURFACES>cont
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.
PROJECTION SURFACES>cont
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PROJECTION SURFACES>cont
PROJECTION SURFACES>cont
PROJECTION SURFACES>cont
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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PROJECTION SURFACES>cont
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.
PROJECTION SURFACES>cont
Example : Polar projections (i.e. Lambert Azimuthal, Stereographic, Gnomonic).
PROJECTION SURFACES>cont
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
ORIENTATION OF A PROJECTION SURFACE
GLOBE CHARACTERISTICS
PROJECTION SELECTION AND EFFECTS
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.
GNOMONIC, STEREOGRAPHIC AND
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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GNOMONIC, STEREOGRAPHIC AND
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
GNOMONIC, STEREOGRAPHIC AND ORTHOGRAPHIC POSITIONS
ORIENTATION OF A PROJECTION SURFACE
GLOBE CHARACTERISTICS
PROJECTION SELECTION AND EFFECTS
ORIENTATION OF A PROJECTION
SURFACE
Cylindrical
Transverse Cylindrical
Oblique Cylindrical
Secant Cylindrical
17/11/2014
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ORIENTATION OF A PROJECTION
SURFACE>cont
Conical Secant Conical Planar Secant Planar
WHAT AND WHY MAPS
PROJECTION SURFACES
GNOMONIC, STEREOGRAPHIC AND ORTHOGRAPHIC POSITIONS
ORIENTATION OF A PROJECTION SURFACE
GLOBE CHARACTERISTICS
PROJECTION SELECTION AND EFFECTS
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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GLOBE CHARACTERISTICS>cont
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
GLOBE CHARACTERISTICS>cont
TOPOGRAPHIC MAPS
GLOBE CHARACTERISTICS>cont
Scale factor along a meridian is equal to 1.
Shape and area of square are distorted.
EQUIDISTANT MAP PROJECTION
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GLOBE CHARACTERISTICS>cont
Applications : Designing cadastral maps.
Projection Examples :
- 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
GLOBE CHARACTERISTICS>cont
CADASTRAL MAPS
GLOBE CHARACTERISTICS>cont
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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GLOBE CHARACTERISTICS>cont
Applications : Designing thematic maps (demographic maps, land use, rainfall).
Projection Examples :
- 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
GLOBE CHARACTERISTICS>cont
THEMATIC MAPS
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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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 & EFFECTS
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.
PROJECTION SELECTION & EFFECTS
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 :