Projections

[Paul Spencer]

You need what is commonly referred to as EPSG:41001, defined as:

<41001> +proj=tmerc +ellps=WGS84 +units=m +no_defs  <>

To use this, add the above line to your 'epsg' file and also add a  
projection object to your map object:

PROJECTION
"init=epsg:41001"
END

You will also need to make sure that every layer in your map file has  
a proper projection so mapserver can reproject it correctly.

Cheers

Paul

On 8-Jul-07, at 9:44 PM, Bradley Mclain wrote:

> This is kind of hard to explain but what I want to do is use  
> Mapserver to project my data which is in the GDA94 projection as  
> shown below:
>
> "# GDA94 / MGA zone 55
> <28355> +proj=utm +zone=55 +south +ellps=GRS80  
> +towgs84=0,0,0,0,0,0,0 +units=m +no_defs  <>"
>
> to a projection that will be able to be properly merged with Google  
> maps (using OpenLayers) which uses a projection something like the  
> following:
>
> "Update 4: Agreement frrom Melita Kennedy and David Burrows that  
> Google Maps and Virtual Earth use spherical equations for the  
> Mercator projection.  The correct proj4  settings are:
>
> +proj=merc +latts=0 +lon0=0 +k=1.0 +x0=0 +y0=0
> +a=6378137.0 +b=6378137.0 +units=m
>
> Note this is different than using the  ellipsoidal equations which  
> would be:
>
> +proj=merc +latts=0 +lon0=0 +k=1.0 +x0=0 +y0=0
> +ellps=WGS84 +datum=WGS84 +units=m no_defs"
>
> I believe that I need to use Mapserver to do this but I have no  
> idea how to go about it. Currently my Mapserver is running fine  
> displaying the data correctly using the GDA94 projection except i  
> had to use a .vrt file to correctly align the raster image which  
> was slightly out of alignment. I have also set up and can call my  
> Mapserver as a WMS (thought having issues with the WMS Layer  
> function in OpenLayers, just displays a white screen but I believe  
> that this is to do with projections)
>
> My Mapserver has been compiled with GD, GDAL, GEOS, PostGIS, PHP  
> and proj4.
>
> In my mapfile I have defined each layer using "init=epsg:28355" as  
> well as globally defining the map using the same projection.
>
> This reason I am trying to do this is because currently I don't  
> think that my projection can be properly imported into OpenLayers  
> and merged with Google Maps.
>
> Thanks
>
> Brad

+-----------------------------------------------------------------+
|Paul Spencer                          pspencer at dmsolutions.ca    |
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|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
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