GeoGrid

Convert between longitude and latitude and Australian Map Grid coordinates using the Australian Geodetic Datum (1966), and also to calculate the distance between two points. Results are unpredictable if applied outside of Australia. Requires a Java enabled browser.

Instructions

• Change a co-ordinate. New co-ordinates and distance values will be recalculated immediately.
• If the Zone is Fixed,
  Changing the Longitude or Latitude will keep the Zone but change the Easting and Northing.
  Changing the Zone will change the Easting and Northing.
• If the Zone is not Fixed,
  Changing the Longitude or Latitude will change the Zone, Easting and Northing.
  Changing the Zone will change the Latitude and Longitude.
  
  Changing the Easting or Northing will never make the Zone Change.

Conventions

• Latitude: + is North, - is South.
• Longitude: + is East, - is West.
• Grid co-ordinates are in kilometres.

Assumptions

• Spheriod distance calculations are based on the Australian National Spheroid.
  Major semi-axis, a = 6 378 160 metres
  Flattening, f = 1 / 298 .250
• The Spherical distance is based on a simple globe of radius 6 378 160 m.

Accuracy

• Spheroid distance accuracy decreases with distance.
  It is accurate to better than 20mm over a distance of 1 500km.
  The error can reach 16m at 4 500km, and more than 2 000m at 9000km.
  The Spheroid distance will not be displayed for distances over 9500km.

Reference

• National Mapping Council of Australia, 1972
  The Australian Map Grid, Technical Manual,
  Special Publication 7