Projections

[Bradley Mclain]

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
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