There are three main methods used to transform New Zealand Geodetic Datum 1949 (NZGD1949) coordinates (latitude and longitude) to New Zealand Geodetic Datum 2000 (NZGD2000).
New Zealand Geodetic Datum 1949 (NZGD1949)
Coordinate systems used in New Zealand
New Zealand Geodetic Datum 2000 (NZGD2000)
NZGD1949 is a horizontal datum, so any transformations which include NZGD1949 are horizontal only. Heights cannot be transformed in terms of NZGD1949.
The common transformation methods are described on the Geodetic datum conversions page. These are 3-parameter similarity, 7-parameter similarity and distortion grid transformations.
Each transformation method has different accuracy limits. Choosing the most appropriate method will depend on the accuracy of the coordinates being converted and what they will be used for.
- 3-parameter similarity transformations have an expected accuracy of 5 metres.
- 7-parameter similarity transformations have an expected accuracy of 4 metres.
- Distortion grid transformations have an expected accuracy of 0.1 to 1.0 metres at the time the distortion grid is calculated. The transformation will become less accurate over time as the datums continue to deform.
These transformations are formally defined in the standard LINZS25000 (Standard for New Zealand Geodetic Datum 2000), and are summarised in the NZGD2000 fact sheet (LINZG25700).
Standard for New Zealand Geodetic Datum 2000 - LINZS25000
New Zealand Geodetic Datum 2000 - LINZG25700