2. DESCRIPTION
Two dimensional representation of the three dimensional Earth
Systematic transformation of latitudes and longitudes to
parallels and meridians respectively
An intriguing component of the coordinate system referencing
because it portrays high level of flexibility
Transformation cause distortion in real world properties that
are:
1. Shape
2. Area
3. Distance
4. Direction
3. DEVELOPABLE PROJECTION SURFACES
Determine specific method of physical projection
Three kinds of developable projection surfaces:
1. Cone
2. Cylinder
3. Plane
The name of the projections made from these surface are:
1. Conic Projection
2. Cylindrical Projection
3. Planar Projection
4. 1. Conic Projection:
Conic projection is fan shaped,
characterized by an upside down cone
over the sphere
Conic projection are at an true scale
along a standard parallel/s between the
equator and a pole
Conic projections are used for
midlatitude zones that have an east–
west orientation
If equally space, distance preserve
If distance between parallels increase
near border, shape preserve
If distance towards north and south
pole decreases, area preserve
5. 2. Cylindrical Projection:
Cylindrical projection is a rectangular
grid representation, characterized by a
cylinder over a sphere
Cylindrical projections are at an true
scale along a central meridian/s and
standard parallel/s near a equator
Cylindrical projection mostly use for
tropical zones
All cylindrical projections are
equidistant along central meridian/s
and standard parallel/s
6. 3. Planar Projection:
Planar projection is a circular
representation with a focus,
characterized by plane over a sphere
Planar projection is also called
Azimuthal projection or Zenithal
projection
Planar projections are true only at
their focus
Planar projections mostly use for
polar zones
Planar projection more better
describe circular regions than
rectangular regions
7. Azimuthal Projection is further
divided into three different
projection on the basis of
projection focus:
1. Gnomonic/ Central projection
2. Stereographic Projection
3. Orthographic Projection
1) Gnomonic Projection:
Azimuthal projection in which
projection focus is at center of
the Earth
8. 2) Stereographic Projection:
Azimuthal projection in which
projection focus is from pole
to pole
3) Orthographic Projection:
Azimuthal projection in which
projection focus is at infinity
9. LOCATION OF DEVELOPABLE PROJECTION
SURFACE
There are two cases in which
developable projection
surface meet Earth:
1. Tangent:
DPS touches the Earth
One standard parallel/ One
Central meridian
2. Secant:
DPS cuts the Earth
Two standard parallels/ Two
central meridians
10. ASPECT OF DEVELOPABLE PROJECTION
SURFACE
Projection aspect is the relative orientation
of the developable projection surface and
Earth with respect to the observer
There are four kinds of projection aspects:
1. Normal
2. Transverse
3. Oblique
4. Polar
1) Normal Aspect:
Oriented with polar axis
Based on parallels
Normal aspect is Equatorial aspect if
standard parallel is equator
Normal aspect is Azimuthal aspect if
standard parallel touches poles
11. 2) Transverse Aspect:
Oriented perpendicular to polar axis
Based on meridians
3) Oblique Aspect:
Oriented at any angle with polar axis
Based on central meridian and
standard parallel
Use for geographical areas that are
centered along lines that are neither
parallel nor meridians
Directed as northwest, northeast,
southwest and southeast
12. 4) Polar Aspect:
Oriented on focus as north or
south pole
Based on straight meridians
with a concentric parallels
Polar aspect only related to
planar projection or
Azimuthal projection or
Zenithal projection
13. PROJECTION CLASSIFICATIONS
Classification defines a properties of the projected surfaces
The names of the properties that preserves by the projected surfaces are
given below:
1. Shape: Conformal or Orthomorphic
2. Area: Equal Area or Equivalent
3. Distance: Equidistant
4. Direction: Azimuthal
1) Conformal Projection:
Preserve shapes of small regions of the Earth that’s why use for medium
scale to large scale applications
Shape preserve either angle preserve or scale preserve
No projection preserve shape of larger regions
Can preserve Direction by maintaining an angle between graticule lines
Area of the region distorted for large scale applications
14. 2) Equal Area or Equivalent:
Preserve area of all regions of the Earth’s surface that’s why use for
small scale to large scale applications
Area preserve when scale vary equally on both sided of the standard
parallel
Area and shape cannot preserve simultaneously
For small scale applications, Direction also distorted
3) Equidistant:
Preserve distance between entire regions of the Earth that are at true
scale that’s why use for small scale to large scale applications
Distance only preserve when scale preserve
No projection is equidistant to and from all points on a map
15. 4) Azimuthal:
Preserve direction of all regions of the Earth that’s why use for medium
to large scale applications
Direction preserve when angle preserve
Azimuthal projection can be equal area, conformal or equidistant
Formation of Map Projections:
DPS can exhibit more than one classification
The conic projection, cylindrical projection and planar projection can be
combined with one or more of the projection classifications to control
the appearance and distortion for any particular application
There are lot of projections that can made by this procedure. Some of
the projections will discussed
16. MERCATOR PROJECTION
Cylindrical projection
Normal aspect
Equator/ Two latitudes symmetrical
around the equator
Meridians are parallel to each other
and equally spaced
Parallels are parallel but become
farther apart toward the poles
Distance preserve along Equator or
Two latitudes
Shape preserve accurately
Direction preserve accurately along
graticule lines
Area not preserved and increase
towards the top and bottom of the map
Use in Standard sea navigation charts,
Wind direction, Air travel and Ocean
currents
Application in Conformal world maps
17. CYLINDRICAL EQUAL AREA PROJECTION
Cylindrical projection
Equatorial aspect
Tangent to the equator
All meridians are equally spaced and
0.32 times the length of the equator
Parallels are equally spaced and
farthest apart near the equator
Poles are lines of length equal to the
equator
Distance preserve along equator
Shape not preserve because of scale
variation
Direction not preserved but local angle
preserve along standard parallels
Area preserve accurately
Use for narrow areas extending along
the equatorial regions
18. UNIVERSAL TRANSVERSE MERCATOR
PROJECTION
Cylindrical projection
Transverse aspect
Two parallel lines spaced from each
central meridian by 180 km
Earth is divided into 60 zones that
are spanning 6⁰ of longitude form
84⁰N & 80⁰S with central meridian of
each zone and equator
Distance preserve along each central
meridian
Shape not preserve accurately
Direction preserve for each zone
Area preserved and minimal
distortion along the boundary of
zone
Extent should be limited to 15⁰-20 ⁰
on both sides of the central meridian
Many countries use local UTM
zones based on the official
geographic coordinate systems in use
19. EQUIDISTANT CONIC PROJECTION
Conical Projection
Normal aspect
Tangential/ Secant
Concentric circles of parallels and all
meridians are evenly spaced
Distance preserve accurately along
meridians and standard parallels
Shape preserve along standard parallels
Direction not preserve but local angle
preserve
Area not preserved and increases as
moving away from standard parallels
Range in parallels should be limited to
30°
Use for Regional mapping of midlatitude
areas with a predominantly east–west
extent
Application in Atlas maps of small
countries
20. ALBERS EQUAL AREA PROJECTION
Conic projection
Normal aspect
Secant
All meridians equally spaced
Distance between concentric
parallels decreases toward poles
Distance preserve for mid latitude
Shape not preserve and distortion
increases between standard parallels
Direction not preserve but local
angle preserve
Area preserve accurately
Used for small countries but not for
continents.
Used for the conterminous United
States
21. LAMBERT CONFORMAL CONICAL
PROJECTION
Conic projection
Normal aspect
Secant
All meridians are equally spaced
Distance between arc of parallels
increases near a border
Distance preserve for mid latitude
Shape preserve accurately
Direction preserve accurately
Area not preserved except small
regions near standard parallels
All latitudinal range should not
exceed 35°
Use for regions that have east-
west extension
22. LAMBERT AZIMUTHAL EQUAL AREA
PROJECTION
Planar projection
Equatorial, polar and oblique aspect
Tangent of single pint anywhere
Equatorial aspect: The equator
Polar aspect: All meridians
Oblique aspect: Central meridian
Distance preserve only along focus
Shape not preserved because of about 2%
error within 15° from focus
Direction preserve accurately from focus
Area preserve accurately
Use for Population density, Political
boundaries
Use in Oceanic mapping for energy,
Minerals, Geology, and Tectonics
23. Use for displaying entire continents
Equatorial aspect: Africa, Southeast Asia, Australia,
the Caribbean, and Central America
Polar aspect: Polar regions
Oblique aspect: North America, Europe, and Asia
24. UNIVERSAL POLAR STEREOGRAPHIC
PROJECTION
Stereographic projection
Polar aspect
Tangent at pole
The focus is either a north pole or south pole
to 84° N and 80° S
The latitude 81°06'52.3" N or 81°06'52.3" S
at true scale and all meridians
Distance preserve only at focus and latitude
of 81°06'52.3" N or 81°06'52.3" S
Shape preserve accurately
Direction preserve accurately from focus
Area not preserve and increases moving
away from focus
Use for Conformal mapping of polar regions
Use for mapping polar regions of the UTM
coordinate system
25. OTHERS PROJECTIONS
The other projections which are not conceptually made and not
easily related to developable projection surface
There are three kinds of these projections:
1. Modified projection
2. Pseudo projection
3. Compromise projection
1) Modified Projection:
Modified form of conceptual projections to reduce distortion
For example, the Space Oblique Mercator projection is a
modified form of Mercator projection, Aitoff is a modified
form of planar projection etc
26. 2) Pseudo Projection:
Have some Characteristics of another class of projection
For example, the Sinusoidal is called a pseudo cylindrical
projection, Bonne is called pseudo conic projection and Werner
is called pseudo planar projection etc
3) Compromise Projection:
Average or interrupted form of different projection
For example, Goode's Homolosine projection is a combination
of the Mollweide and sinusoidal projections etc
