[GRASS5] Fw: Use of LINZ grid file

H Bowman hamish_nospam at yahoo.com
Mon Jun 23 02:52:12 EDT 2003

[email addresses and phone numbers removed to protect the innocent; 
   entire email cc Paul Kelly, others upon request;
   cc PROJ.4 list if it is of use to anyone there]

Here is some correspondence between me & Land Information New Zealand.

micro-executive summary:
.. we can distribute the New Zealand NTv2 grid file with GRASS if we like ..

I did try using the .gsb file with the 5.0 CVS snapshot of GRASS as per Paul's instructions, but couldn't get it to work properly. But I can't get cs2cs to work with it now either, so I'll have to sort that out first. (file not found)
I did have it working with cs2cs a couple of weeks back though..?

- ASCII version of the grid available for individual download
- Binary NTv2 .gsb file is in the GD2000it distribution
- NZGD2000 is WGS84 +/- < 0.10m


Begin forwarded message:

Date: Mon, 16 Jun 2003 13:28:41 +1200
Subject: Use of LINZ grid file

Hi Hamish,
As you have stated the LINZ web site does not explicitly state the
limitations on usage of the NTv2 distortion model between NZGD49 and
NZGD2000.  However the implied limitations that apply to the C code are
also applicable to the grid file. 

Therefore you can use the grid file for whatever purpose you like,
however the following (as you have quoted) applies: 
*  This software may be freely used and modified.  It is provided as is,
*  where is, with no guarantees as to its correct functioning.  Land
*  Information New Zealand accepts no liability for any consequences 
*  of the use of this software.
In summary, you are free to use the grid file in your software, however
LINZ accepts no responsibility or liablility for any consequences of its
I hope this helps.
Matt Amos

Matt Amos
Geodetic Specialist
Office of the Surveyor-General
Toitu te whenua
Land Information New Zealand
Website: http://www.linz.govt.nz


> Hello -
> I am collaborating with the developers of the Open-Source (free) GRASS
> GIS software project[1]. Recent updates to the GIS include support for
> datum transformations via the PROJ.4 library[2], which among other
> things can be used to convert from WGS84 to NZGD49 and NZ Map Grid
> within the GIS.
> Browsing LINZ site, I found some transform data available for free
> download[3], included both with the GD2000it software package (in
> binary form) and on its own in ASCII format within file
> "nzgd2kgrid9911.zip".
> Specifically, those downloads provide a "distortion grid in NTv2
> format".
> As the latest versions of PROJ.4 (and thus GRASS GIS) now support NTv2
> transformations, making NZMG now quite simple and accurate to use
> along side lat-lon projects, we would like to redistribute a binary
> version of the distortion grid standard with the GIS suite.
> It is unclear to me from those software downloads what the licensing
> disposition of the grid files are though.
> The "source code in the C programming language that implements the
> conversion between NZGD2000 and NZGD1949 using the NTv2 ASCII
> distortion grid file" provided at the LINZ website states the
> following:
> *  This software may be freely used and modified.  It is provided as is,
> *  where is, with no guarantees as to its correct functioning. Land
> *  Information New Zealand accepts no liability for any consequences
> *  of the use of this software.
> *
> *  Copyright: Land Information New Zealand 2001
> *  Author: Chris Crook
> However, the required ASCII grid (a separate download) carries no such
> notice. All "for more information" web links to LINZ within the
> attached Readme file fail.
> The GD2000it software license agreement[4] states in section 3.2
> "Subject to clause 3.3 the Licensee shall not copy, alter, modify or
> reproduce the Data without the Suppliers prior written consent."
> Section 1 defines Data as "the transformation grid file and source
> code".
> Note that while the .gsb binary grid file is distributed with the
> software, it must be loaded (with the equivalent of File->Load) the
> first time the program is run, and thus the grid file may be free (to
> LINZ) from the license obligations to Univeristy of Melbourne that the
> the rest of the GD2000it software may be subject to.
> Note also that if it is ok to use the the ASCII version of the grid
> file but not the binary copy distributed with the GD2000it software,
> the ASCII version may be easily converted by us into a binary form we
> could use.
> Clarification and/or written consent to redistribute would be greatly
> appreciated, as having full, built-in, highly accurate support for NZ
> datums and projections in a GIS suite that is freely available for
> unlimited student and home use, as well as to those without the
> US$20,000 in their budget for a comparable proprietary system, would
> be a real boon to many Kiwis.
> thanks for your help,
> Hamish
> [1] http://grass.itc.it
> [2] http://www.remotesensing.org/proj
> [3]http://www.linz.govt.nz/rcs/linz/pub/web/root/core/SurveySystem/Ge
> odeticInfo/software/index.jsp
> [4] Help->Contents->Technical Information->GD2000it Licence Agreement

More information about the grass-dev mailing list