New Zealand has jurisdictional responsibility for a number of offshore islands. To facilitate the consistent topographic mapping and integration of spatial datasets a series of map projections has been defined.
These are all Transverse Mercator projections and are based on the NZGD2000 datum using the GRS80 reference ellipsoid. The distortion in transverse Mercator projections increases with distance from the longitudinal central meridian; consequently different projections have been defined for the different offshore island groups. The projections have been defined so that no two points on land will have the same numerical coordinates in terms of different projections.
The offshore island projections are formally defined in the LINZS25002 (Standard for New Zealand Geodetic Datum 2000 Projections). The key parameters from this standard are summarised below:
| Projection type: | Transverse Mercator |
|---|---|
| Reference ellipsoid: | GRS80 |
| Datum: | NZGD2000 |
| Origin latitude / central meridan: | 0° 00' 00" South |
| False Northing: | 10,000,000 metres North |
| False Easting: | 3,500,000 metres East |
| Central meridian scale factor: | 1.0000 |
| Area | Projection Name | Abbreviation | Origin Longitude |
|---|---|---|---|
| Chatham Islands | Chatham Islands Transverse Mercator 2000 |
CITM2000 | 176° 30' West |
| Snares Islands / Tini Heke and Auckland Islands |
Auckland Islands Transverse Mercator 2000 |
AKTM2000 | 166° 00' East |
| Campbell Island / Motu Ihupuku | Campbell Island Transverse Mercator 2000 |
CATM2000 | 169° 00' East |
| Antipodes and Bounty Islands |
Antipodes Islands Transverse Mercator 2000 |
AITM2000 | 179° 00' East |
| Raoul Island and Kermadec Islands | Raoul Island Transverse Mercator 2000 |
RITM2000 | 178° 00' West |
