This page contains information on how to download and install the SNAP and CONCORD programs.
If you are using SNAP you are encouraged to register for email notifications of updates.
SNAP (Survey Network Adjustment Package) is a suite of programs for adjusting the coordinates of stations in a survey network to best fit the observed data. It can use GPS data (baselines or multistation vector and point data), horizontal angles, zenith distances, slope and horizontal distances, azimuths, projection bearings, levelled height differences, latitude, longitude, and height observations.
SNAP runs on most recent versions of Microsoft Windows and is supplied as 32 and 64 bit versions (note that SNAP binary files are not compatible between 32 and 64 bit versions).
From here you can download the SNAP installation file snap_install.msi in a zip file. To install SNAP extract and run the installation file.
Some of the utility programs supplied with SNAP require the perl interpreter to be installed on the computer. This is can be obtained from the Activestate website.
A guideline for surveyors using SNAP for Order 5 control Surveys can be found on the geodetic specification page.
CONCORD is a component of SNAP that converts coordinates between various different coordinates systems such as New Zealand Map Grid coordinates, Meridional Circuit Coordinates and NZGD49 or NZGD2000 latitude and longitude coordinates. CONCORD is an DOS command line program (run from a windows DOS box).
CONCORD can be downloaded separately from the SNAP suite. To install it extract the contents of the downloaded zip file into a folder, and set the PATH environment variable to include that folder.
The source code for concord with build instructions for a linux environment is available at http://github.com/linz/concord.
Last updated 5 December 2017
The CONCORD component of SNAP (zip 19MB)
Last updated 5 December 2017
Download and use of these software applications is taken to be acceptance of the following conditions:
- LINZ does not offer any support for this software.
- The software is provided "as is" and without warranty of any kind. In no event shall LINZ be liable for loss of any kind whatsoever with respect to the download, installation and use of the software.
- The software is designed to work with MS Windows. However, LINZ makes no warranty regarding the performance or non-performance of the software on any particular system or system configuration.
SNAP add on packages
The following add-on packages are available for SNAP. To use a package download and save the ZIP file, then use the snap_manager install function (in the Tools menu) to add them to SNAP.
LINZ geodetic contractor tools
LINZ geodetic contractor package (zip 4KB)
Adds support for managing test adjustments required for LINZ geodetic control contracts
Dynanet import package
The Dynanet import package (zip 8KB)
Adds a function to import Dynanet XML files into SNAP. Last updated 17 August 2010
SINEX import package
The SINEX import package (zip 8KB)
Adds a function to convert coordinate/covariance information from SINEX files to SNAP data files. Last updated 15 August 2014.
Note that SNAP can now read SINEX files directly so that this package is redundant.
The AUSGeoid09 package (zip 3.8MB)
Installs AUSGeoid09 V1.01 into SNAP for calculating geoid heights in Australia. Last updated 17 August 2014
NewGan import package
The NewGan import package (zip 19KB)
Adds a function to import NewGan input files into SNAP. (Note: this is "beta" software - it has only received limited testing). Last updated 17 August 2010
5 December 2017
This version (2.7.8) updates the NZGD2000 deformation model to version 20171201. It also includes a number of enhancements to the coordinate system definition file (coordsys.def) and to SNAP.
7 October 2017
This version (2.7.6) contains additional bug fixes and adds the option of including vertical height datums in the coordinate definition, for example NZGD2000/NZVD2016.
18 May 2017
This version (2.7.4) provides a number of small fixes relating to coordinate precision, date conversions, and ITRF2014 parameters.
19 November 2016
This version (2.7.1) provides two main enhancements. Firstly it allows defining vertical datums in the coordinate system file. This means that concord can convert heights between different vertical datums. Also the geoid used in adjustments can be based on a vertical datum. Secondly it adds more sophisticated and readable commands for reweighting, rejecting, and ignoring observations.
25 June 2016
This version includes the version 20160701 of the New Zealand deformation model and the New Zealand geoid 20160701. Also provides numerous small enhancements to options in the SNAP command file.
16 June 2015
There is a software fix for the SNAP version dated 4 May 2015. This contained a sign error in the definition of reference frame transformations in the SNAP command file and output listing file. This version should be updated.
4 May 2015
Enhancements to SNAP for:
- Reading and writing SINEX files
- Defining and calculating 14 parameter transformations between reference frames
- Translating station codes when reading from data files (eg if data files have different names to SNAP coordinate files)
- JSON format outputs for easier integration with scripting languages
12 January 2015
Extended NZGD2000 deformation model to cover the New Zealand Exclusive Economic Zone
15 August 2014
Added Australian and Antarctic coordinate systems. Minor bug fixes and improved error messages.
10 February 2014
Fix a bug in the 29 January 2014 that can cause the SNAP command file to be deleted when data files are updated using snap_manager.
29 January 2014
Updated the NZGD2000 deformation model to version 20140201, incorporating the 2013 Cook Strait and Lake Grassmere earthquakes as forward patches.
8 January 2014
Adds a configuration menu in snap_manager for handling various sorts of configuration files.
17 December 2013
Updates SNAP and concord to include the NZGD2000 deformation model version 20130801. Also more rigorous conversion between NZGD2000 and other International reference frames (for example ITRF2008), which properly account for the date of the coordinates. Improvement in the management of SNAP user configuration files. Numerous other minor updates.
4 October 2010
Adds a new feature to SNAP for reading station information and observation data from CSV (delimited text files) as an alternative to the SNAP format files, as well as several other small enhancements. The listgps program is renamed to snaplist. For more information review the change log in the help file.
23 August 2010
Minor update to SNAP configuration files relating to orders. Inclusion of the site2gps program into the SNAP package.
24 May 2010
The accuracy specifications for NZGD2000 orders in snap and snapspec configuration files have been updated to implement the LINZS25006 standard for tiers, classes, and orders. Also enhanced SNAP to support additional data types (XYZ point positions, orthometric heights) and angles formatted as decimal degrees.
14 October 2009
Fixes a bug in SNAP causing it to require dates to be supplied for observations even if the adjustment does not include a deformation model.
6 October 2009
The NZGeoid09 geoid model has replaced the previously used unofficial NZGeoid05 model in concord and SNAP. Also a number of functional enhancements to SNAP.
18 March 2009
Fix to snapspec when assigning orders using a posteriori statistics. Update to concord to include Darwin Glacier Lambert Conic coordinate system.
31 July 2008
Update to the import GDB stations function to work with the restructured LINZ website.
29 April 2008
Added listgps program to SNAP distribution, which was previously omitted.
8 February 2008
Removed system limits on the number of stations and parameters in a SNAP adjustment, previously limited to 32,000. Note that SNAP binary files generated used by this version are incompatible with previous versions of SNAP.