Transcript RESOLUTION - Centre For Integrated Mountain Research

Topics: Map Projection
UTM
Scales
Resolution
Presented By
Atif Rasheed
Zul Kanawal
Hira Akram
Hina Pervaiz
Topic
Map projection
Index
What is Map Projection
Why we need Map Projection
Developable and Undevelopable surfaces
Latitudes and Parallel of latitudes
Longitudes and Meridian of longitudes
Classification of Map Projection
Map projection
What is Projection?
“A map projection is representation of 3D
body on a 2D plane.”
“A map projection is a systematic representation
of parallels of latitude and meridians of
longitude of the spherical globe on a plane
surface.”
Map projection
Representation
Globe
Map
Map projection
Why we Need Projection
Because a Globe

Difficult to carry

Not easy to construct

Expensive

Difficult to measure distances on globe

Cannot show small area on a large scale
Map projection
DEVELOPABLE SURFACE
UNDEVELOPABLE SURFACE
Map projection
Latitude and Parallel of Latitude
In order to describe positions on a sphere we use the Latitude, Longitude
coordinate system.
Latitude is the vertical
angular distance from the
equator to the point on
surface. Its measured from
the center of the globe 90
degrees North (0 to +90)
or South (0 to -90) .
Map projection
Parallels of Latitude
ZONE
Area between two successive
parallels of latitude. It runs in
East-West direction. Its
length is maximum at
equator and decrease away
from it.It is zero at the pole.
Map projection
Longitude and Meridian of Longitude
Longitude is the horizontal
angular distance from the
Prime Meridian to the point
on surface. Its measured
from the center of the globe
180 degrees East (0 to +180)
or West (0 to -180). The
Prime meridian is also
referred to as the Greenwich
Meridian.
Map projection
Parallels of Longitude
GORE
Area between two successive
meridians on map. Its run in
North-South direction. On the
globe its width is maximum at
the equator and goes on
decreasing as we move away
from equator. Its become zero
at the poles.
Map projection
GRATICULE
network of parallels and
meridians drawn on plane
surface.
Help in locating different
places with reference to given
latitude and longitude.
Map projection
Classification of map projections
1
2
3
• Method of construction/development
• Characteristics of map projections
• Use of light
Map projection
Classification of projections based on their
characteristics

Homolographic/Equal Area projection - the areas
represented on the map are equal to the area on the globe.
Shapes are disturbed. It used for statistical purpose.

True shape /Conformal / Orthomorphic projection the shapes of places are accurate. Area become faulty. Use for
navigation purpose.

True Direction / Azimuthal projection - angles of
direction are accurate. Used to show transport routes.

True Scale - scale of parallels and meridians are correct.

Distance - measured distances are accurate
Map projection
Classification of projections according to Use of light
Perspective projections
NON-PERSPECTIVE PROJECTIONS
Cylindrical
Conical
Zenithal
References:
http://earth.rice.edu/mtpe/geo/geosphere/topics/projections.j
pg
http://en.wikipedia.org/wiki/Map_projection
http://geography.about.com/library/weekly/aa031599.htm
Practical Geography for B.A. B.Sc. by Mian Mohammad Anwar
Mercator’s projection
On this Mercator projection, (mathematically derived, cylindrical type),
Greenland and South America appear similar in size. The inset map
shows that South America is actually about 15 times larger than
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Greenland.
Mercator’s projection
Cylindrical Projection (Mercator): is based on a cylinder tangent to the
equator. Good for equatorial regions but greatly distorted at high
latitudes. This one of the oldest and most common projections.
Gerardus Mercator invented his famous projection in 1569 as an aid to
navigators. On his map, lines of latitude and longitude intersect at right
angles and thus the direction of travel - the rhumb line - is consistent.
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Mercator’s projection
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Mercator’s Projection / Cylindrical Orthomorphic Projection
Properties:
1. All parallels & meridians are straight lines.
2. The meridians intersect the parallels at right angles.
3. The distances between the parallels go on increasing towards the poles
but distances between the meridians remain the same.
4. Length of all the parallels is same & is equal to the length of the equator.
The length of the equator on this projection is equal to the length of the
equator on the globe. Therefore, the scale along the equator is correct.
5. The meridians are longer than the corresponding meridians on the
globe.
6. The parallels are longer than the corresponding meridians on the globe.
So, the exaggeration of parallel scale at the pole is infinite.
7. At a point, the scale along the meridian is equal to the scale along the
parallel. Therefore the projection is also called “Orthomorphic
Projection”
Merits:
Demerits:Polar areas cannot be shown due to the exaggeration of parallels
& meridians.
Uses: For navigational purposes in sea & air.Ocean currents, wind directions
& pressure systems are shown on this projection due to its true
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directions. For showing tropical countries for general purposes.
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Loxodromes/ rhumb line
Since the shape and direction are true for every point, straight lines
represent lines of constant bearing on the real sphere. These straight
lines are called loxodromes/ rhumb line.
Maps, Their Uses and Construction, G J
Morrison (Edward Stanford, 1902) p29
Map Projections, H S Hoblin
(Edward Arnold,
1969) p23
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Universal Transverse Mercator (UTM)
The ellipsoidal form of the Transverse Mercator projection was developed
by Carl Friedrich Gauss in 1825 but it did not come into common usage
until after World War II. It has become the most used because it allows
precise measurements in meters to within 1 meter.
It was further analysed by Johann Heinrich Louis Krüger in 1912. The
projection is known by several names:
Gauss Conformal or Gauss-Krüger in Europe;
Transverse Mercator in the US; or
Gauss-Krüger Transverse Mercator generally
The projection is conformal with a constant scale on the central meridian.
The Universal Transverse Mercator coordinate system was developed
by the United States Army Corps of Engineers in the 1940s.The system
was based on an ellipsoidal model of Earth. For areas within the
conterminous United States, the Clarke 1866 ellipsoid was used. For the
remaining areas of Earth, including Hawaii, the International Ellipsoid was
used. Currently, the WGS84 ellipsoid is used as the underlying model of
Earth in the UTM coordinate system.
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Universal Transverse Mercator (UTM)
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Universal Transverse Mercator (UTM)
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Universal Transverse Mercator (UTM)
Universal North Polar(UNP)
Universal South Polar(USP)
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UTM grid
Maximum northing value = 9,328,000 meters at the 84˚parallel
False Origin of Northern Hemisphere = 0 at equator
False Origin of Southern Hemisphere = 10,000,000
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meters
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Standard (or Normal) Mercator and the Transverse Mercator
Properties
The standard (or Normal) Mercator and the Transverse Mercator are two
different aspects of the same mathematical construction. Because of the
common foundation, the Transverse Mercator inherits many traits from the
Normal Mercator.
1.
2.
3.
4.
Both projections are cylindrical: for the Normal Mercator, the axis
of the cylinder coincides with the polar axis and the line of tangency
with the equator. For the Transverse Mercator, the axis of the
cylinder lies in the equatorial plane, and the line of tangency is any
chosen meridian, thereby designated the central meridian.
Both projections may be modified to secant forms, which means the
scale has been reduced so that the cylinder slices through the model
globe.
Both exist in spherical and ellipsoidal versions.
Both projections are conformal, so that the point scale (The scale
of a map is defined as the ratio of a distance on the map to the
corresponding distance on the ground.) is independent of
direction and local shapes are well preserved;
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REFERENCES:
http://geology.isu.edu/geostac/Field_Exercise/topomaps/utm.htm
http://geology.isu.edu/geostac/Field_Exercise/topomaps/utm.htm
http://egsc.usgs.gov/isb/pubs/factsheets/fs07701.html
http://www.progonos.com/furuti/MapProj/Dither/ProjTbl/Img/tnSinusoidal.png
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What is Scale? (in context to
maps)
O
Scales
Scales depends on
O The size of area to be mapped
O The amount of detail to be shown
O The size of paper
Scale is shown in three ways
O Statement of scales(S.S)
O Representative Fraction/Numerical Scales (R.F)
O Plain/Linear/Graphic Scale
Statement of Scales(S.S)
In this scale we state direct that one inch represents
so many miles or 1 mile is represented by so many
inches
It is written as
1 inch to 1 mile
3 inch to 1 mile
Small Scales
are scales of miles to inches e.g.
4 miles to 1 inch
64 miles to 1 inch
Large Scales
are scales of inches to mile
2 inches to 1 mile
6 inches to 1 mile
Representative Fraction/
Numerical Scale(R.F)
O
Plain/Linear/Graphic Scale
O It consists of a line drawn at the bottom of
the map conveniently divide and subdivided
so that distances on the map can easily be
read from it.
Scales
Exercise
Exercise
Conclusion:
O It is EXTREMELY IMPORTANT to science as it is a
standardized and regulated set of measurements
without which it is difficult to deal with very large and
very small quantities.
Resolution
Resolution is the capability of the sensor to
observe or measure the smallest object clearly
with distinct boundaries. And it refers to the
sharpness and clarity of an image
Pixel resolution
Pixel: A pixel is actually a unit of the digital
image. ‘OR’ Pixel is a picture element.
‘OR’ Pixel resolution is defined as the
ground cell area that is detected by the area
e.g 1m,2m,10m.
Image resolution
1
Spatial resolution
2
Spectral resolution
3
Temporal resolution
4
Radiometric resolution
Spatial Resolution
The measure of how closely lines can be
resolved in an image is called spatial
resolution.
‘OR’
Pixel resolution is the spatial resolution also.
Spectral Resolution
Spectral resolution describes the ability of a sensor
to define fine wavelength intervals. The finer the
spectral resolution, the narrower the wavelength
range for a particular channel or band.
Temporal Resolution
Time between two succesive images at the same
location is known as temporal resolution.
This amount of time depends on the orbital
characteristics of the sensor platform as well as
sensor characteristics. The temporal resolution is
high when the revisiting delay is low and vice-versa.
Radiometric Resolution
Minimum observable difference of DN value is
known as radiometric resolution.
REFRENCES
http://www.nrcan.gc.ca/earthsciences/geomatics/satellite-imagery-airphotos/satellite-imagery-products/educationalresources/9393
http://www.tutorialspoint.com/dip/Spatial
_Resolution.htm
http://www.crisp.nus.edu.sg/~research/tutorial/
image.htm