GPS and remote sensing

1. CEB 809: Lecture 6
Universal Transverse Mercator
Projection and Grid Systems
UTM Projection
Projection Surface
UTM Zones and Grid
WGS 1972

3. The Variables in Map Projection
Projection Orientation or Aspect
Gnomonic
Stereographic
Orthographic
Transverse Oblique Normal
Plane
Cylinder
Cone

4. Projection Families

5. oGnomonic:
The projection center is at the center of the ellipsoid.
oStereographic:
The projection center is at the opposite side
oopposite the tangent point.
oOrthographic:
The projection center is at infinity.

6. Map Projection Distorts Reality
 Transfer from 3D globe to 2D map must
result in loss of one or more global
characteristics:
o Shape
o Area
o Distance
o Direction
o Position

7. Classification of Projections
 Projections are classed by
o The global characteristic preserved.
o Geometric approach to construction.
projection surface
“light” source
o Orientation.

8.  Conformal (Shape)
 Equivalent (Area)
 Equidistant (Distance)
 Azimuthal (Direction)

9. UTM Projection :
UTM provides georeferencing at high levels of
precision for the entire globe
established in 1936 by the International Union
of Geodesy and Geophysics
adopted by the US Army in 1947
adopted by many national and international
mapping agencies
is commonly used in topographic and thematic
mapping, for referencing satellite imagery and
as a basis for widely distributed spatial
databases

10. UTM Projection :
In the UTM Grid system, the area of the earth
between 84̊ N and 80̊ S latitude is divided into
north-south column 6̊ of longitude wide.
This columns are called zones, numbered from
1 to 60 eastwards
It begins at the 180th meridian.
Each column is divided into quadrilaterals of 8̊
of latitude

11. THE FORMATION/DEVELOPMENT OF UTM GRID
SYSTEM OR PROJECTION

12. THE FORMATION/DEVELOPMENT OF UTM GRID
SYSTEM OR PROJECTION

13. THE FORMATION/DEVELOPMENT OF UTM GRID
SYSTEM OR PROJECTION

14. Transverse Mercator Projection
based on the Mercator Projection
but in transverse rather than
equatorial aspect
meaning that the projection is
analogous to wrapping a cylinder
around the poles rather that around the
equator.

15. Transverse Mercator Projection

16. UTM System
UTM system is secant, with lines of scale 1 located
on both sides of the central meridian.
The projection is conformal, so small features
appear with the correct shape and scale is the
same in all directions.
Scale is 0.9996 at the central meridian and at most
1.0004 at the edges of the zone.
Both parallels and meridians are curved on the
projection, with the exception of the zone’s central
meridian and the equator

18. The Zones
in order to reduce distortion the globe is
divided into 60 zones, 6 degrees of longitude
wide
zones are numbered eastward, 1 to 60, beginning at
180 degrees (W long)
the system is only used from 84 degrees N to 80
degrees south as distortion at the poles is too
great with this projection
at the poles, a Universal Polar Stereographic
projection (UPS) is used

20. The Zones & Quadrants
each zone is divided further into strips of 8
degrees latitude forming quadrants;
beginning at 80 degrees S, are assigned letters C
through 84 degrees N are assign X, O and I are
omitted
O and I are omitted because they look more or
like zero and one

26. HOW UTM GRID SQUARES ARE DIVIDED

27. HOW UTM GRID SQUARES ARE DIVIDED

28. HOW UTM GRID SQUARES ARE DIVIDED

29. HOW UTM GRID SQUARES ARE DIVIDED

30. Coordinates
coordinates are expressed in metres
eastings (x) are displacements eastward
northings (y) express displacement northward
the central meridian is given an easting of
500,000 m

31. Coordinates
the northing for the equator varies
depending on hemisphere
when calculating coordinates for locations in
the northern hemisphere, the equator has a
northing of 0 m
in the southern hemisphere, the equator has
a northing of 10,000,000 m

33. NORTHING

35. EASTHING

37. Location on topographic map using UTM
coordinate system

38. Location on topographical map using UTM
coordinate system
1000 sq.m
100 sq.m

40. Australian Geodetic Datum and
Australian Map Grid
The Australian Geodetic Datum (AGD) produces a
single datum for Australia and its Territories using
Australian National Spheroid (ANS)
The Australian Map Grid (AMG) is derived from
UTM map projection of latitudes and longitudes on
the AGD
The UTM projection of AGD66 co-ordinates, using
the ANS, gives the AMG66

41. WGS 1972
Fiji uses WGS 1972 as it’s datum.

42. Regional and Global Spheroids and
Datums
There is a distinction between the spheroid and
the datum
The spheroid is a geometrical reference surface
The datum is the adopted coordinate set based on a
particular spheroid
Not all geographical latitudes and longitudes of
the same surface location are equal, but depend
on the spheroid and coordinate datum
referenced

43. Regional Spheroids and Datums
A regional reference spheroid is chosen so as to fit
the Geoid as closely as possible over the mapped
area
Enables subsequent geodetic data collected on the
physical surface of the earth to be reduced to the
surface of the spheroid without introducing
significant horizontal scale error
Best fitting spheroid in one region not necessarily
the best fit in another
Different reference spheroids in different regions
e.g. Australian National Spheroid

44. Global Spheroids and Datums
Global spheroid corresponds to the best fit geoid
over the entire earth
Satellite-derived geodetic data enabled improved
determinations of the global spheroid
Internationally recognised global geocentric
spheroid derived with inclusion of satellite
observations was Geodetic Reference system 1967
(GRS67)
Refined and superceded by Geodetic Reference
System 1980 (GRS80)

45. Global Spheroids and Datums
Most recent global geocentric spheroid used widely
is the World Geodetic System 1984 (WGS84)
WGS84 spheroid is based on the GRS80 spheroid
with slight difference in flattening due to rounding
errors
GPS provides positions referenced WGS84
spheroid
GPS is envisaged to be used in majority of
positioning and navigation applications

46. WGS 1972 & 1984
For mapping purposes, Fiji used WGS
1972 while WGS 1984 is primarily used for
GPS location.

47. Basic map elements
Information commonly needed by the map
reader
 Almost all maps must include certain basic elements that
provide the reader with critical information.
These are;
title,
scale,
legend,
body of t he map,
north arrow ,
cart ographer,
neat line,
dat e of product ion,
project ion used,
and information about sources.

48. Thank you!