OUTLINE

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GEOREFERENCING SYSTEMS

• OUTLINE
• description of georeferencing systems
• cartesian/plane coordinates
• global systems
• local systems

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GEOREFERENCING SYSTEMS

• method for representing/identifying locations on
  earths surface
• purposes
• location of a specific map feature may be
  measured and recorded for future use
• known coordinates of a feature may be used to
  find and map its location
• number of different systems based on variety of
  datums, units, projections and reference systems

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TYPES IN USE

• Plane/Rectangular Coordinates
• used for locating points on a flat map
• cartesian coordinates and modern form
• Geographical Coordinates
• primary system
• used for locating positions on uniformly curved
  surface

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CARTESIAN SYSTEMS

• mathematical coordinate system defined by
  distance away from origin
• locate an origin
• set two axes through origin in fixed directions,
  at right angles to each other
• x is horizontal axis (east) and y is vertical
  axis (north)

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CARTESIAN SYSTEMS
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CARTESIAN SYSTEMS

• calculate distance between locations

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CARTESIAN SYSTEMS

• Advantages
• based on simple mathematics
• Disadvantages
• coordinates tied to that particular projection
  and spatial extent

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GLOBAL SYSTEMS

• Latitude and Longitude
• angular measurements
• expressed as decimal degrees or
  degrees/minutes/seconds
• global coverage

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LATITUDE AND LONGITUDE

• prime meridian and equator are reference planes
  used to define longitude or latitude (divide
  earth into two spheres

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LATITUDE AND LONGITUDE

• Latitude
• latitude angular measurement of a place
  expressed in degrees north or south of the equator

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LATITUDE AND LONGITUDE

• Latitude
• parallel line connecting all points along the
  same latitudinal angle (name of the line).
• run from 0o at equator to 90o N/S at poles in an
  east-west direction

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LATITUDE AND LONGITUDE

• distance between parallels does not change
  significantly

• one degree of latitude 111 km one minute
  1.6 km one second 30 m

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LATITUDE AND LONGITUDE

• Longitude
• longitude angular measurement of a place east or
  west of a reference meridian (Prime Meridian).

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LATITUDE AND LONGITUDE

• Longitude
• meridian line connecting all points along the
  same longitude.

• run in N-S direction from pole to pole from 0o
  to 180o E/W

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LATITUDE AND LONGITUDE

• meridians converge at poles
• longitude varies from 111 km (equator) to 0
  (poles)

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LATITUDE AND LONGITUDE
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LATITUDE AND LONGITUDE

• Degrees to Decimal Degrees
• example 45 33' 22" (45 degrees, 33 minutes, 22
  seconds).

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LATITUDE AND LONGITUDE

• Advantages
• global coverage (supports small scale maps)
• Disadvantages
• parallels are not really equally spaced (approx.
  1 km difference from pole to equator)
• many significant digits are required for high
  precision mapping

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GLOBAL SYSTEMS

• Universal Transverse Mercator (UTM)
• based on the transverse Mercator projection, with
  scale exaggeration increases away from the
  standard meridian
• meter is the basic unit of measurement (instead
  of degrees).
• uses northings and eastings instead of latitude
  and longitude

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GLOBAL SYSTEMS

• Universal Transverse Mercator (UTM)
• divided into N-S columns 6o of longitude wide
  columns are called zones

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GLOBAL SYSTEMS

• Universal Transverse Mercator (UTM)
• each column is divided into quadrilaterals of 8o
  of latitude

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GLOBAL SYSTEMS
columns numbered 1-60 eastward, rows are assigned
letters C to X each quadrilateral is assigned a
number-letter combination
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GLOBAL SYSTEMS
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UTM GRID

• expressed as eastings and northings
• Northings
• measure distance north in meters from zero to 10
  million
• northings are always positive

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UTM GRID

• southern hemisphere, equator is given false
  northing of 10,000,000 m to avoid (-) Northings.

• northern hemisphere equator is assigned
  northing values of 0 m North

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UTM GRID

• Eastings
• referenced to the center line of the zone known
  as the central meridian
• central meridian for each zone is assigned an
  easting value of 500,000 m

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UTM GRID

• Eastings
• measure distance east in metres from central
  meridian (false easting)
• an easting of zero will never occur, since a 6o
  wide zone is never more than 674,000 m wide

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UTM GRID
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UTM GRID

• ex. 14U     629,443E     5 521 654N
• from the left, the first number is the UTM zone
  (or column), the letter is the row designation
• so this location is 626,443 meters left (west) of
  zone 14's central meridian, and 5,521,654 meters
  up (north) from the equator.

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• Locating on a UTM Map
• Look for zone number and mark it down (important
  to have this indicated)
• Read right to the grid intersection before your
  place of interest. Then measuring right in
  meters from intersection will give the complete
  easting
• Do the same in the Y direction.

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Example Drill Hole Zone 13 704250E
3391520N Therefore the drill hole is located
3,391,250 m north of the equator
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Drill hole location with easting of
704250E Without Zone 13 indicated, this easting
would not indicate in which UTM zone the hole is
located (in the middle of Pacific or over
Africa??)
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• Examples
• Hilltop 3726?
• Zone 13 705775E 3391395N
• Hilltop 3774?
• Zone 13 705580E 3390680N

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UTM GRID

• Advantages
• real distances (in meters)
• excellent for large-scale maps
• Disadvantages
• distortion above 80o latitude
• non-global coverage

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GLOBAL SYSTEMS

• Universal Polar Stereographic
• special UTM zones used to cover the polar areas
  (northern hemisphere 84o-90o southern hemisphere
  80o-90o)
• each pole divided into half (N pole - Y and Z
  grids S pole A and B grids)
• false eastings and northings are given a value of
  2,000,000 meters

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GLOBAL SYSTEMS

• World Geographic Reference System (GEOREF)
• used for aircraft navigation
• based on latitude and longitude
• globe is divided into 12 bands of latitude and 24
  zones of longitude, each 15o in extent
• 15-degree areas further divided into one degree
  units identified by 15 characters

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GLOBAL SYSTEMS
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GLOBAL SYSTEMS

• 15-degree areas further divided into one degree
  units identified by 15 characters

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GLOBAL SYSTEMS

• two numeric characters designate the integer
  number of minutes of longitude east of the one
  degree quadrangle boundary longitude.
• two additional numeric characters designate the
  number of minutes of latitude north of the one
  degree quadrangle boundary latitude.

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GLOBAL SYSTEMS

• Postal codes
• Telephone codes

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