Vertical datum relationship grids

Vertical datum relationship grids are reference surfaces that can be used to transform heights between the 13 official local vertical datums and New Zealand Vertical Datum 2016 (NZVD2016).

New Zealand has 13 official local vertical datums (LVDs), which were established by determining mean sea level (MSL) and then transferring this throughout a benchmark network. In contrast, New Zealand’s national height datum is now New Zealand Vertical Datum 2016 (NZVD2016), which is referenced to the reference surface New Zealand Quasigeoid 2016 (NZGeoid2016).

Local mean sea level datums

New Zealand Vertical Datum 2016

New Zealand Quasigeoid 2016

Heights can be converted between an LVD and NZVD2016 by applying an offset correction (https://www.linz.govt.nz/guidance/geodetic-system/understanding-coordinate-conversions/converting-between-nzvd2016-nzgd2000-and-local-vertical-datums). The value of the offset depends on horizontal position, so a relationship grid is needed.

Converting between NZVD2016, NZGD2000 and local vertical datums

The vertical datum relationship grids are on a 2’ x 2’ arc (approximately 3.6km x 3.6km) grid across the area covered by the datum. 

Find out how the grids were computed

The vertical datum relationship grids are described in the table below.

Local vertical datumRelationship grid extents
One Tree Point 196434.3°S – 36.8°S, 172.6°E – 175.0°E
Auckland 194636.1°S – 38.0°S, 174.0°E – 176.2°E
Moturiki 195336.5°S – 40.7°S, 174.5°E – 178.3°E
Gisborne 192637.4°S – 39.0°S, 177.0°E – 178.6°E
Napier 196238.6°S – 40.6°S, 175.6°E – 177.9°E
Taranaki 197038.3°S – 41.1°S, 173.6°E – 176.4°E
Wellington 195339.1°S - 41.6°S, 174.4°E – 176.4°E
Nelson 195540.4°S – 42.7°S, 171.3°E – 174.4°E
Lyttelton 193741.3°S – 45.1°S, 168.5°E – 174.2°E
Dunedin 195843.9°S – 46.5°S, 168.4°E – 171.3°E
Dunedin-Bluff 196045.0°S – 46.7°S, 167.4°E – 169.9°E
Bluff 195546.3°S – 46.8°S, 168.2°E – 169.9°E
Stewart Island 197746.5°S – 47.5°S, 167.2°E – 168.8°E

The location and extent of each LVD is shown in the image below.

Map showing LVD extents over NZ

Map of New Zealand showing LVD location and extents

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