You can use this adjustment to apply changes to your own data sets to realign them with LINZ data after the update has been applied.
Download Kaikoura 2017 update NTv2 (.gsb) file
For more information about the update to the NZGD2000 datum refer to Kaikoura earthquake coordinate update. Technically this update is transforming the horizontal coordinates from the pre-earthquake version of the NZGD2000 datum, version 20160701, to the post-earthquake version 20171201. This is not the same as the actual movement caused by the earthquake.
It is important to note that this adjustment should only be applied to data that is not already updated for the Kaikoura earthquake deformation. The coordinates of survey control marks and data in the LINZ Landonline database (for example cadastral parcel data) is planned be updated on the weekend of 9 December 2017. Other LINZ data will be updated shortly after this as the change is replicated through the various data sets. If you are using these layers we recommend that you reload them after they have been updated by LINZ.
If you have not updated your database for the South Island update refer to South Island coordinate update. The 2013 update should only be applied once please check with your system administrator to see whether your database is up to date.
OGR is part of the GDAL toolkit. It can be used to apply the adjustment using a NTv2 grid shift defined in the .gsb files.
GDAL/OGR can be freely downloaded for Windows, MAC and LINUX from this GDAL binary download page.
Alternatively, you can download the (OSGeo4W) Open Source Geospatial toolkit. This also provides an extensive set of tools such as the QGIS desktop GIS.
Before running the adjustment, copy the appropriate .gsb grid file (see link at top of page), to the <GDAL/OGR install directory>/share/proj directory.
Note:
If the directory naming is different on your install, find it by searching for “nzgd2kgrid0005.gsb”. This file will be in the correct directory.
Note:
Make sure the source data has NZGD2000 as its coordinate reference system. We do not provide a file to adjust data that is in NZTM2000 for OGR2OGR.
Run the command below:
ogr2ogr --debug on -f "ESRI Shapefile" -s_srs "+proj=longlat +ellps=GRS80 +nadgrids= nzgd2000_20171201_reverse_patch.gsb" -t_srs "+proj=longlat +ellps=GRS80 +towgs84=0,0,0,0,0,0,0" shifted_data.shp data_to_shift.shp
Tip:
This example shows how to apply the shift to a shapefile. Ogr2ogr supports most spatial data formats. To see all valid formats and for a usage guide to ogr2ogr type “ogr2ogr” in your command line.