Coordinates System

• Coordinate Systems


  • Geodetic Latitude
  • Longitude
  • Equator
  • Prime Meridian
  • Central Meridian
  • False Eastings
  • False Northings

  
• Coordinate measurements


  Taken from a source that is accepted as the origin and some form of measurement is used to describe the movement from the point of origin to the desired destination

  
• Normal PNG expression of distance is measured by time taken to travel that route
• The modern day measurements takes in the form of both, time and length, and that is expressed in Coordinate systems
• Coordinate systems specify locations on the surface of the earth have been used for centuries

  
• The equator, the tropics of Cancer and Capricorn, and then lines of latitude and longitude expressed in Degrees, Minutes and Seconds were used to locate positions measured from a known origin on the earth's surface

  
• To standardize positioning now for global mapping and especially for safety in navigation only one origin for points of origin is accepted

  
• Various units of length and angular distance were been used over history
• Meter


  Related to both linear and angular distance, having been defined in the late 18th century as one ten-millionth of the distance from the pole to the equator

  
• Other measurements based on the Degrees, Minutes and Seconds, the Nautical Miles also measure from the origins of a defined system that today we come to learn as the Universal Accepted Measures of our universe earth
• Geographic Coordinate System


  Latitude, Longitude, and Height (Ф, λ, Ht)

  
• The most commonly used coordinate system today is the Geographic Latitude, Longitude, and the height system

  
• Prime Meridian and the Equator


  Define the reference planes or the origins of latitude and longitude and the Ellipsoid Surface for the Height determination

  
• Global Positioning Systems/ Global Navigation Satellite System (GPS/GNSS)


  The Universal Global Geodetic Datum of WGS84 is configured to read Geographical locations based on the Reference points or a line of Zero Meridian as the Prime Meridian as the origin of the Longitude, and the Equator as origin of Latitude

  
• Equator


  Origin of Latitude measurement

  
• All Latitude measurements are in the direction of North-South. Points north of the Equator are positive in latitudes and below the Equator are Negative

  
• Latitude


  Northings represented on the UTM
• PNG is located below the Equator or South of the origin of Zero Degree Latitude, and so all Latitudes measured anywhere in PNG is Negative
• Geodetic latitude of a point


  The angle from the equatorial plane to the vertical direction of a line normal to the reference ellipsoid

  
• Prime Meridian


  Zero meridian that runs along Greenwich, in Great Britain. This Zero Meridian is the starting line for all the Meridians measured to the West and East directions, towards PNG

  
• PNG is located between the Longitude of 141º East to 160º East, overlapping into Solomon Islands
• Longitude


  Eastings represented in UTM Format

  
• Geodetic longitude of a point

  Measured from the reference plane and a plane passing through the point, both planes (latitude & Longitude) being perpendicular to the equatorial plane

  
• Geodetic height at a point


  The distance from the reference ellipsoid to the point in a direction normal to the ellipsoid
• Earth Centered, Earth Fixed X, Y, and Z

  Cartesian coordinates used to define three dimensional positions

  
• From History of Geodesy ONLY GRS80 and WGS84 are Earth Centered Ellipsoids

  
• Earth centered, earth-fixed, X, Y, and Z, Cartesian coordinates (XYZ)


  Define three dimensional positions with respect to the center of mass of the reference ellipsoid

  
• 1. axis


  Points toward the North Pole. This is also the direction of the Polar Axis, the Minor (b)
• 1. axis


  Defined by the intersection of the plane defined by the prime meridian and the equatorial plane

  
• 1. axis


  Completes a right handed orthogonal system by a plane 90° east of the X-axis and its intersection with the equator. This is along the plane of the Equator

  
• ECEF coordinate systems are very usefull for Datum and System transformation

  
• Origin of ECEF Cartesian Coordinate System


  The Centre of Physically Earth Defined by the GPS

  
• Universal Transverse Macator (UTM)


  The most used system by surveyors. The system is in meters where points are defined by the UTM Eastings and UTM Northings from an origin
• All lines of Geodetic Longitudes (Meridian Lines) are divided into Zones of equal 6º. The Central Meridian or the mid meridian line divides the zone into two with 3º to the West and 3º to the East

  
• UTM Eastings


  In order to keep coordinates a positive entity all the time, a False Eastings of 500,000m and False Northings of 10,000,000m is created. Origin of the UTM Eastings fall on the Central Meridian of any specified Zone

  
• Points falling on the West of the Central Meridian will bear negative values so when added to 500,000 fales Eastings will yield coordinates of lees than 500,000m. Likewise points that fall East of the Central Meridian will bear positive coordinates along the Eastings plane so will bear more than 500,000 Eastings

  
• UTM Northings


  The One Tenth Millionth m defined from the Equator falls as the Origin of the Northing direction measurements

  
• All points in PNG bears Northing of LESS than 10,000,000m. Traversing towards the Equator will bring us closer to the 10,000,000m
• Points falling south of the Equator will bear negative values so when added to the False Northings will yield values of less than 10,000,000m. PNG and the rest of the countries south of the Equator will all have Northings values of less than 10,000,000m
• All coordinate systems are referenced to a Given Geodetic Datum. Measurements taken on an Ellipsoid that has the geodetic parameters defining its Ellipsoid by: a = Major Axis, and f= the Flattening factor