Friday, September 25, 2009

New topographic map series for New Zealand

Yesterday LINZ has released a new map series of topographic maps for 1:50,000. It is also known as Topo50. Significance of this release is in fact that it is based on New Zealand Transverse Mercator projection and NZGD2000 – new datum for New Zealand.

Details, samples and other information is available on new web site Topo50 Map.

Main reason for change of map series is summarized in FAQ section:
The change was required as a result of Land Information New Zealand releasing a new national datum New Zealand Geodetic Datum 2000 (NZGD2000) to replace the New Zealand Geodetic Datum 1949 (NZGD1949).

The NZGD1949 datum was a ‘local’ datum that was no longer accurate enough and was limited by the survey technology available at the time. The accuracy has also degraded significantly due to the natural process of earth deformation.

The NZGD2000 datum is an ‘international’ datum and for all practical purposes is the same as that use by GPS.
As a result of this datum change coordinates on map series have moved by 190m in north/sourh and 10m east/west direction.

On Downloads page there is a PDF with fact sheet (only 114 KB) with details of NZTM2000 (New Zealand Transverse Mercator 2000) and how to use new maps with GPS.

Transverse Mercator
Origin Latitude
0.0 degrees South
Origin Longitude
173.0 degrees East
False Northing
10,000,00 m North
False Easting
1,600,000 m East
Central Meridian scale factor

If you are outside of New Zealand and you are using NZ maps make sure you get new ones.

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