Is it True north? Grid North, AMG North, Magnetic North, Google North, Nautical North, Arbitrary North or some other North….???
It comes down to what you need North for and the purpose and in the design and construction industry – architects and engineers, surveyors, data managers, GIS personnel, etc, we use the different north points for their end needs.
The 3 main North options are True, Grid & Magnetic, but as you can see, there are other North Point options and I am sure there are more than what are shown here, but we think we have the key ones.
Each day the Earth rotates about its axis. The two ends of the axes are the True North and True South poles. True North on a map is the direction along the Earth’s surface which converges on the North Pole.
Grid North is the direction of a plane grid system, usually the grids associated with the projection of a map.
Australian Map Grid (AMG) North
The projected coordinate system based on the superseded Australian Geodetic Datum, was based initially on the Australian National Spheroid (ANS) which was an ellipsoid designed to be the best estimate of the earth’s shape around the Australian continent rather than the world.
A compass needle points to the magnetic north pole. The magnetic north pole changes slightly with time and with location of the Earth’s Surface?
Google Maps North
Google Maps use a variant of the Mercator projection for its map images. The Mercator map was designed as an aid to navigators since straight lines on the Mercator projection are loxodromes or rhumb lines – representing lines of constant compass bearing – perfect for ‘true’ direction.
True North on Google Maps is not shown, but for a normal Mercator projection, grid north and true north will coincide and it will follow any vertical line (or meridian) to the top of the map. (google)
Pretty well aligns with True North
Arbitrary North can be in any direction at all and is not tied or linked by mathematical means to any of the north options.