[MetaCRS] Re: [OpenLayers-Dev] New Zealand Map Grid in OpenLayer and Proj4js

[Mike Adair]

Hi Stephen,

I've added the NZMG code to Proj4js 
(http://trac.osgeo.org/proj4js/ticket/1) but there is a couple of problems:

-  I'm not a licensing expert but we can't use the GPL license for this 
because it is too restrictive.  Can you change that to LGPL like the 
rest of the library?  If so please put a comment to that effect on the 
ticket.

- The test points aren't quite matching up, errors are consistent with 
the datum shift you describe in the code.  Can you provide some test 
points for the 2 coordinate systems to WGS84 please?  That will help 
isolate any problems.

Thanks for the contribution.

Mike

Stephen Irons wrote:
> Thank you. I saw the proj4js Trac website, but there were no tickets 
> entered, so I assumed it was not in use.
>
> There is now one ticket open...hope someone else finds the NZMG 
> transformation useful.
>
> Stephen
>
>
> On Thu, 2008-07-10 at 09:07 -0400, Mike Adair wrote:
>> Cool! We're still in the process of moving the project infrastructure 
>> for proj4js but in the meantime you can enter a ticket and patch in the 
>> Trac system at: http://trac.osgeo.org/proj4js/
>> And eventually it should make it's way into the code base.
>>
>> Mike
>>
>>
>>
>> Stephen Irons wrote:
>> > I have implemented a Proj4js transformation for New Zealand Map Grid 
>> > (NZMG) co-ordinates (EPSG:27200). spatial-reference.org 
>> > <http://spatial-reference.org> gives a description of the 
>> > transformation, but the '+proj=nzmg' was not available in the current 
>> > version in the repository. This projection is not related to any of 
>> > the existing types, so I implemented it.
>> >
>> > I would like to contribute this code to Proj4js. However, it is not 
>> > obvious how to submit this code to the project. Can anyone here point 
>> > me to the right place?
>> >
>> > Stephen Irons
>> >
>> >
>> > Background
>> >
>> > New Zealand Map Grid (NZMG) is a projection used to convert latitude 
>> > and longitude to easting and northing coordinates in metres. It was 
>> > designed to minimize the scale error over the land area of New Zealand 
>> > and cannot be used elsewhere.
>> >
>> > The New Zealand govnernment survey agency, LINZ (Land Information New 
>> > Zealand) has published two series of maps covering the mainland areas 
>> > of New Zealand.
>> >
>> >     * 262-series is 1:250000
>> >     * 260-series is 1:50000
>> >
>> > These maps are available in printed form and are currently the only 
>> > large-scale maps of New Zealand widely available to the general 
>> > public. Vector data is also available.
>> >
>> > Various commercial concerns have scanned these maps, or generated 
>> > tiles from the vector data, and released products using these tiles. I 
>> > have one of these products and want to use the tiles with OpenLayers.
>> >
>> > New Zealand Map Grid
>> >
>> > New Zealand Map Grid was designed by Dr W. I. Reilly in 1973. Its 
>> > official specification is published as /New Zealand Map Grid/, 
>> > Department of Lands and Survey Technical Circular 1973/32. A scanned 
>> > image of the publication is available at 
>> > http://www.linz.govt.nz/docs/miscellaneous/nz-map-definition.pdf
>> >
>> > It is also described in /Conversion between Latitude and Longitude and 
>> > New Zealand Map Grid/, OSG Technical Report 4.1, 1998. This document 
>> > is available at http://www.linz.govt.nz/docs/miscellaneous/nzmg.pdf
>> >
>> > NZMG is given EPSG code EPSG:27200. It is defined at 
>> > http://spatialreference.org/ref/epsg/27200/proj4/ as
>> >
>> >     * "+proj=nzmg +lat_0=-41 +lon_0=173 +x_0=2510000 +y_0=6023150
>> >       +ellps=intl +datum=nzgd49 +units=m +no_defs"
>> >
>> > Now, most of this is known to Proj4js code. However, the projections 
>> > 'nzmg' is not know, and needs to be implemented.
>> >
>> >
>> > ------------------------------------------------------------------------
>> >
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>> >   
>>
>>