Vertical Datum Relationship Grids

Heights can be transformed between the 13 major local vertical datums and New Zealand Vertical Datum 2016 (NZVD2016) using relationship grids.

The 13 local vertical datums (LVD) datums are defined in terms of mean sea level at their respective standard ports. They offset from each other and from NZVD2016. The value of this offset varies depending on horizontal position; this means that a relationship grid is required when transforming heights between datums. 

The vertical datum relationship grids can be used in conjunction with NZGeoid2016 to transform NZGD2000 ellipsoidal heights to normal-orthometric heights in terms of the local datums. The relationships between the different height surfaces are shown in the figure below.

Diagram showing the relationship between different height surfaces

Diagram showing the relationship between different height surfaces

The vertical datum relationship grids are calculated using the values from the local datum to NZGeoid2016. These values are interpolated on a 2’ x 2’ arc grid of which covers the datum extent. The vertical datum relationship grid values are positive when NZGeoid2016 is above the local datum.

Local vertical datum

Relationship grid extents

One Tree Point 1964

34.3°S – 36.8°S, 172.6°E – 175.0°E

Auckland 1946

36.1°S – 38.0°S, 174.0°E – 176.2°E

Moturiki 1953

36.5°S – 40.7°S, 174.5°E – 178.3°E

Gisborne 1926

37.4°S – 39.0°S, 177.0°E – 178.6°E

Napier 1962

38.6°S – 40.6°S, 175.6°E – 177.9°E

Taranaki 1970

38.3°S – 41.1°S, 173.6°E – 176.4°E

Wellington 1953

39.1°S - 41.6°S, 174.4°E – 176.4°E

Nelson 1955

40.4°S – 42.7°S, 171.3°E – 174.4°E

Lyttelton 1937

41.3°S – 45.1°S, 168.5°E – 174.2°E

Dunedin 1958

43.9°S – 46.5°S, 168.4°E – 171.3°E

Dunedin-Bluff 1960

45.0°S – 46.7°S, 167.4°E – 169.9°E

Bluff 1955

46.3°S – 46.8°S, 168.2°E – 169.9°E

Stewart Island 1977

46.5°S – 47.5°S, 167.2°E – 168.8°E

There is a unique vertical datum relationship grid for each of the LVD, the location and extents of which are shown in the image below. 

Map showing LVD extents over NZ

Map of New Zealand showing LVD location and extents

Region Local vertical datum number of control marks Mean (m) Standard Deviation Min (m) Max (m) Range (m) Reference Mark Datum Relationship at Reference Relationship Grid  Grid Version
One Tree Point  One Tree Point 1964 137 0.077 0.042 -0.03 0.155 0.185 RNZN BM (DJM9) 0.080 OTP64-NZVD16 2016.1
Auckland  Auckland 1946 260 0.292 0.029 0.226 0.367 0.142 98-21 SO 69501 (DD1N) 0.367 AUK46-NZVD16 2016.1
Moturiki  Moturiki 1953 519 0.309 0.071 0.140 0.540 0.401 BC 84 (B309) 0.199 MOT53-NZVD16 2016.1
Gisborne  Gisborne 1926 274 0.343 0.025 0.253 0.397 0.143 GB 01 (ACVP) 0.361 GSB26-NZVD16 2016.1
Napier Napier 1962 207 0.203 0.034 0.124 0.299 0.175 H 40 (B3XM) 0.193 NPR62-NZVD16 2016.1
Taranaki  Taranaki 1970 125 0.286 0.026 0.216 0.356 0.140 New Plymouth Fundamental (AGMH) 0.297 TNK70-NZVD16 2016.1
Wellington  Wellington 1953 137 0.408 0.054 0.296 0.517 0.221 K 80/1 (ABPB) 0.388 WGN53-NZVD16 2016.1
Nelson  Nelson 1955 256 0.329 0.039 0.215 0.440 0.225 N 1 (AC4T) 0.330 NSN55-NZVD16 2016.1
Lyttelton  Lyttelton 1937 923 0.340 0.041 0.200 0.489 0.289 UD 40 (B40V) 0.389 LTN37-NZVD16 2016.1
Dunedin  Dunedin 1958 197 0.326 0.043 0.174 0.458 0.284 WW 83 (AFEQ) 0.377 DUN58-NZVD16 2016.1
Dunedin-Bluff  Dunedin-Bluff 1960 205 0.254 0.039 0.154 0.364 0.210 Z 41 (B3R8) 0.329 DBL60-NZVD16 2016.1
Bluff  Bluff 1955 71 0.273 0.034 0.213 0.352 0.138 Bluff Fundamental (ABCC) 0.316 BLF55-NZVD16 2016.1
Stewart Island  Stewart Island 1977 4 0.299 0.025 0.276 0.338 0.062 N (Paterson SD) (A017) 0.299 STI77-NZVD16 2016.1