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Introduction

NTv2 stands for National Transformation version 2, and describes a binairy grid format, used to perform high accuracy datum conversions between coordinates. The National Transformation format has been developed by Canada's Geodetic Survey Division (GCS). The format has been adapted to several other countries, including Australia.

A single NTv2 file can contain various grids with different accuracies. Software has to be designed in a way that a coordinate is converted using the most accurate grid available. To get the actual datum shift for a coordinate, the 4 closest known coordinates are retrieved from a grid file, and then interpolated using bi-linear interpolation. The default extension for NTv2 grid files is .GSB (Grid Shift Binary). There is also an ASCII variant of this file, which is using the extension .GSA (Grid Shift ASCII).

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Australia

Usage

NTv2 is used in Australia to convert coordinates between the AGD66 (Australian Geodetic Datum 1966) and GDA94 (Geocentric Datum of Australia 1994) datuns, and to convert between AGD84 (Australian Geodetic Datum 1984) and GDA94 (Geocentric Datum of Australia 1994).

Example(s)

AGD66	GDA94

Longitude	Latitude	Longitude	Latitude
143.000000 E	20.000000 S	143.001128 E	19.998487 S

AGD84	GDA94

Longitude	Latitude	Longitude	Latitude
143.000000 E	20.000000 S	143.001152 E	19.998472 S

Grid File(s)

A66 National (13.09.01).gsb
National 84 (02.07.01).gsb

Download

click to download the AGD66 <> GDA94 NTv2 grid file (A66 National (13.09.01).gsb)
click to download the AGD84 <> GDA94 NTv2 grid file (National 84 (02.07.01).gsb)

Source

ICSM GDA Technical Manual

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Brazil

Usage

NTv2 is used in Brazil to convert coordinates between the Corrego Alegre 1961, Corrego Alegre 1970-72, SIRGAS 2000 and WGS84 datums.

Grid File(s)

CA61_003.gsb
CA7072_003.gsb

Download

click to download the Corrego Alegre 1961 <> SIRGAS 2000 / WGS84 NTv2 grid file (CA61_003.gsb)
click to download the Corrego Alegre 1970-72 <> SIRGAS 2000 / WGS84 NTv2 grid file (CA7072_003.gsb)

Source

Instituto Brasileiro de Geografia e Estatística

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Canada

Usage

NTv2 is used in Canada to convert coordinates between the NAD27 (North American Datum 1927) and NAD83 (North American Datum 1983) datums.

Example(s)

NAD27	NAD83

Longitude	Latitude	Longitude	Latitude
2669005.73 m	565767.91 m	7102502.98 m	619119.47 m

Grid File(s)

ntv2_0.gsb

Download

click to download the NAD27 <> NAD83 NTv2 grid file (ntv2_0.gsb)

Source

Natural Resources Canada / Canadian Spatial Reference System

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France

NTv2 is used in France to convert coordinates between the NTF (Nouvelle triangulation de la France) and RGF93 (Réseau géodésique français 1993) datums.

Example(s)

NTF (Lambert Zone II)	RGF93 (Lambert-93)

Northing	Easting	Northing	Easting
2669005.73 m	565767.91 m	7102502.98 m	619119.47 m
2558633.80 m	731608.00 m	6990790.26 m	783942.75 m

Grid File(s)

ntf_r93.gsb

Download

click to download the NTF <> RFG93 NTv2 grid file (ntf_r93.gsb)

Source

IGN Projet Lambert 93

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Germany

Usage

NTv2 is used in Germany to convert coordinates between the DHDN (Deutsches Hauptdreiecksnetz) and ETRS89 (European Terrestrial Reference System 1989) datums.
The grid file used is beta2007.gsb.

Example(s)

DHDN (3-degree Gauss zone 2)	ETRS89 (UTM Zone 32)

Northing	Easting	Northing	Easting
5930677.98 m	2598417.33 m	5928794.18 m	399340.60 m

Grid File(s)

beta2007.gsb

Download

click to download the DHDN90 <> ETRS89 NTv2 grid file (beta2007.gsb)

Source

Beschreibung der Transformation - DE_DHDN (BeTA, 2007) nach ETRS89

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Great Brittain

Usage

NTv2 is used in Great Brittain to convert coordinates between the OSGB1936(Ordnance Survey Great Brittain 1936) and ETRS89 (European Terrestrial Reference System 1989) datums. This conversion grid is also called OSTN02.

Example(s)

ETRS89	OSGB36 (British National Grid)

Latitude	Longitude	Northing	Easting
54.305 N	2.23 W	489955.87 m	385131.61 m

Grid File(s)

ostn02.gsb

Download

click to download the OSGB36 <> ETRS89 NTv2 grid file (ostn02.gsb)

Source

Ordnance Survey

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New Zealand

Usage

NTv2 is used in New Zealand to convert coordinates between the NZGD1949 (New Zealand Geodetic Datum 1949) and NZGD2000 (New Zealand Geodetic Datum 2000) datums.

Example(s)

NZGD1949	NZGD2000

Latitude	Longitude	Latitude	Longitude
39.645 S	175.629 E	39.643242 S	175.629209 E

Grid File(s)

nzgd2kgrid0005.gsb

Download

click to download the NZGD1949 <> NZGD2000 NTv2 grid file (nzgd2kgrid0005.gsb)

Source

NZGD1949 - NZGD2000 Distortion Grid

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Eye4Software Coordinate Calculator

Using the Eye4Software Coordinate Calculator, you can convert coordinates from one map datum to another easily, using the user friendly user interface. This software is shipped with a database containing allmost any map datum, reference ellipsoid and map grid around. The software includes a number of datum and grid definitions that use NTv2 conversion.

For more information, please have a look at the Eye4Software Coordinate Calculator product page.

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