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

[Stephen Irons]

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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> > Dev at openlayers.org
> > http://openlayers.org/mailman/listinfo/dev
> >   
> 
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