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

[Mike Adair]

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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