outline: description of georeferencing systems cartesian/plane coordinates global systems local...

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

GGEOREFERENCING EOREFERENCING

SSYSTEMSYSTEMS

GEOREFERENCING SYSTEMS

method for representing/identifying locations on earth’s 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

TYPES IN USE 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

CARTESIAN SYSTEMSCARTESIAN SYSTEMS

mathematical coordinate system defined by distance away from origin

1. locate an origin

2. 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)

calculate distance between locations


Advantages

based on simple mathematics

Disadvantages

coordinates tied to that particular projection and spatial extent


GLOBAL SYSTEMSGLOBAL SYSTEMS

1.1. Latitude and LongitudeLatitude and Longitude

angular measurementsangular measurements

expressed as decimal degrees or expressed as decimal degrees or degrees/minutes/secondsdegrees/minutes/seconds

global coverageglobal coverage

LATITUDE AND LONGITUDELATITUDE AND LONGITUDE

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

i.i. LatitudeLatitude

latitude:latitude: angular measurement of a place expressed angular measurement of a place expressed in degrees north or south of the equatorin degrees north or south of the equator


i.i. LatitudeLatitude

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


distance between parallels does not change distance between parallels does not change significantlysignificantly

one degree of latitude = ~111 km; one minute = 1.6 km; one second = 30 m


ii.ii. Longitude Longitude

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


ii.ii. 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


meridians converge at poles

longitude varies from 111 km (equator) to 0 (poles)


Prime MeridianInternational Date Line

Degrees to Decimal Degrees

example: 45° 33' 22" (45 degrees, 33 minutes, 22 seconds).


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


2. 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


2.2. Universal Transverse Mercator (UTM)Universal Transverse Mercator (UTM)

divided into N-S columns 6o of longitude wide – columns are called zoneszones


2.2. Universal Transverse Mercator (UTM)Universal Transverse Mercator (UTM)

each column is divided into quadrilaterals of 8o of latitude


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


56o56o

Ce

ntr

al

Me

rid

ian C

entral M

eridia

n


UTM GRIDUTM GRID

expressed as eastings and northings

NorthingsNorthings measure distance north in meters from zero

to 10 million northings are always positive

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

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

UTM GRIDUTM GRID

EastingsEastings 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

UTM GRIDUTM GRID

EastingsEastings 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

UTM GRIDUTM GRID

y

x

N. Hemisphereorigin is

(500,000m, 0)

x

y

S. Hemisphereorigin is

(500,000m, 10,000,000m)

UTM GRIDUTM 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.

UTM GRIDUTM GRID

Locating on a UTM Map

1. Look for zone number and mark it down (important to have this indicated)

2. Read right to the grid intersection before your place of interest. Then measuring right in meters from intersection will give the complete easting

3. Do the same in the Y direction.

Example:

Drill Hole

Zone 13 704250E 3391520N

Therefore the drill hole is located 3,391,250 m north of the equator

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??)

Examples

1. Hilltop 3726?Zone 13

705775E

3391395N

2. Hilltop 3774?Zone 13 705580E

3390680N

Advantages

“real” distances (in meters)

excellent for large-scale maps

Disadvantages distortion above 80o latitude non-global coverage

UTM GRIDUTM GRID

3.3. Universal Polar StereographicUniversal Polar Stereographic

special UTM zones used to cover the polar areas special UTM zones used to cover the polar areas (northern hemisphere 84(northern hemisphere 84oo-90-90oo; southern hemisphere ; southern hemisphere 8080oo-90-90oo))

each pole divided into half (N pole - Y and Z grids; S each pole divided into half (N pole - Y and Z grids; S pole – A and B grids)pole – A and B grids)

false eastings and northings are given a value of false eastings and northings are given a value of 2,000,000 meters2,000,000 meters


Note grid designation- starts east at 0 longitude 84N/80S towards 180E

World Geographic Reference System (GEOREF)World Geographic Reference System (GEOREF)

used for aircraft navigationused for aircraft navigation

based on latitude and longitudebased on latitude and longitude

globe is divided into 12 bands of latitude and 24 globe is divided into 12 bands of latitude and 24 zones of longitude, each 15zones of longitude, each 15oo in extent in extent

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


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


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.


Postal codes

Telephone codes


outline: description of georeferencing systems cartesian/plane coordinates global systems local...

Documents

ongitude slide

curved surface slide

longitude longitude

longitude meridian

latitude latitude

vertical axis north

ongitude prime meridian

poles longitude