New Zealand offshore island projections

Projections are selected so that they best represent an area on a flat surface. There are separate transverse Mercator projections for each of the following offshore islands: Antipodes, Auckland, Bounty, Campbell Island / Motu Ihupuku, Chatham, Kermadec, Raoul and Snares Islands / Tini Heke Islands.

Toitū Te Whenua has responsibilities for mapping and supporting the use of spatial data for New Zealand and its surrounding offshore islands. Different mapping projections will best represent the data of different areas, so individual projections have been created for each of the offshore island groups.

There will always be some distortion when coordinates are converted from a curved surface, such as Earth, to a flat map. Projections help to manage this distortion so the resulting map best supports the needs of its users. The projection used on the New Zealand mainland, New Zealand Transverse Mercator 2000 (NZTM2000), has distortion in its east-west extents. As a result it is not recommended for mapping offshore islands, and separate projections are used for New Zealand's continental shelf:

New Zealand Continental Shelf Lambert Conformal 2000 (NZCS2000)

The projections for our offshore island have been developed using a transverse Mercator projection. This is cylinder-shaped and is well suited for depicting elongated areas, like New Zealand. The false Northing and Easting coordinates of the different projections ensure that different points on land will not have the same coordinates, reducing the chance of confusion.

The offshore island projections are defined in the LINZ standard LINZS25002:

Standard for New Zealand Geodetic Datum 2000 Projections

The key parameters from this standard are summarised below
Projection typeTransverse Mercator
Reference ellipsoidGRS80
Origin latitude / central meridan0° 00' 00" South
False Northing10,000,000 metres North
False Easting3,500,000 metres East
Central meridian scale factor1.0000
AreaProjection NameAbbreviationEPSG numberOrigin Longitude
Chatham IslandsChatham Islands
Transverse Mercator 2000
CITM200017965176° 30' West
Snares Islands / Tini Heke and
Auckland Islands
Auckland Islands
Transverse Mercator 2000
AKTM20003788166° 00' East
Campbell Island / Motu IhupukuCampbell Island
Transverse Mercator 2000
CATM20003789169° 00' East
Antipodes and
Bounty Islands
Antipodes Islands
Transverse Mercator 2000
AITM20003790179° 00' East
Raoul Island and Kermadec IslandsRaoul Island
Transverse Mercator 2000
RITM20003791178° 00' West
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