[mapserver-users] Projection question - Australia

[Marie Flanagan]

Thanks everyone for the replies so far.  I was very pleasantly surprised
that my question got answers so quickly!

I've managed to create a file (using Mapinfo) with the projection I want
i.e. MGA55 on the GDA94 datum.  But I need the units to be in lat and
longitude degrees - as opposed to x,y meters.

For example take a point

888070 6248580

I want this to be represented as

151.1925896 -33.83179046

I 've tried using PROJ4 to covert to degrees, but am not having any luck
(possibly because I don't really understand what I'm doing and the
documentation doesn't help me much).  This is my PROJ4 command ....

proj -v -I -f  "%d" +proj=utm +ellps=WGS84 +a=6378137 +rf=298.25
888070 6248580

I get ...

1080240235 1078729873

Can anyone advise or suggest an alternative approach?  Thanks a lot.

Marie


----- Original Message -----
From: <Andrew.Loughhead at csiro.au>
To: <theflan at gofree.indigo.ie>
Cc: <mapserver-users at lists.gis.umn.edu>
Sent: Thursday, April 11, 2002 3:46 AM
Subject: RE: [mapserver-users] Projection question - Australia


> My take on this:
>
> AMG55 == UTM zone 55 projection on the AGD66 datum.
> (AMG meaning Australian Map Grid, AGD Australian Geodetic Datum).
>
> MGA55 == UTM zone 55 projection on the GDA94 datum.
> (MGA meaning Map Grid of Australia, GDA Geocentric Datum of Australia).
>
> GDA94 and WGS84 are apparently the same for most purposes.
>
> Note that if the flat file is correctly described, AMG must mean
> AGD66 datum.
>
> Anyway, to answer your question I think you need to use the Projection
> Utility that comes with Arcview 3.2 (NOT the 'projector' extension,
> Projection Utility is a standalone program).  This will do the
> datum conversion for you.  If you don't have Arcview there are other
> programs that will do it for you, I'm not familiar with PROJ4 but
> would be suprised if it can't do this.
>
> my AUD $0.04 worth, hth,
> Andrew
>
> > -----Original Message-----
> > From: Lyndon Zimmermann [mailto:lyndon.zimmermann at adelaide.edu.au]
> > Sent: Thursday, 11 April 2002 10:21 AM
> > To: Marie Flanagan
> > Cc: mapserver-users at lists.gis.umn.edu
> > Subject: Re: [mapserver-users] Projection question - Australia
> >
> >
> > Marie,
> >
> > I would say that the AMG Zone 55 you refer to is equivalent
> > to UTM Zone
> > 55, so the various desktop packages should provide that translation.
> > ArcView and ArcTOOLBOX do.  There are other point by point conversion
> > tools around.  Note the new GDA94 is close enough to WGS84 with a
> > vertical translation.
> >
> > Lyndon Z
> >
> >
> > > Marie Flanagan wrote:
> > >
> > > Hi all,
> > >
> > > I have a question about projection.  My map data of the NSW area of
> > > Australia uses WGS84 datum and spheroid.  Units are in geographic
> > > Digital Degrees.  This looks fine when displayed in mapserver.
> > >
> > > I also have a flat file of x,y co-ordinates from the AMG
> > zone 55 which
> > > I want to overlay on the map.  I have managed to figure out how to
> > > generate a shape file for this.  But I am now left with the question
> > > of how to convert from AMG cartesian co-ords to WGS longitude and
> > > latitude.  I think it may be possible to convert these using
> > > PROJ4 before I create the shape file, but I am not sure if it's
> > > possible to convert from AMG to WGS.
> > >
> > > I will continue to search for PROJ4 examples to see if this is
> > > possible but in the meantime if anyone could advise I would be most
> > > grateful.  I am not a cartographer so excuse any obvious
> > ignorance in
> > > the wording of my question!
> > >
> > > Regards,
> > >
> > > Marie
> >
> > --
> > Lyndon Zimmermann
> > BE (Mech Adelaide) Grad Dip Bus Admin (UniSA)
> >
> > LOW RAINFALL AGROFORESTRY RESEARCH UNIT
> > PhD Researcher
> > CRC for Plant-Based Management of Dryland Salinity
> >
> > University of Adelaide Department of Agronomy and Farming Systems
> > Physical address: Hannaford Building (via Gate 3) Waite Campus, South
> > Australia
> > Postal: Adelaide University, PMB1 Glen Osmond, SA 5064, Australia
> > Dir (Soil and Water) +61-8-8303 6571 Mob 0414 91 4577
> > Fax +61-8-8303 6717 email lyndon.zimmermann at adelaide.edu.au
> >
> > Unless otherwise stated, the content of this message and
> > attachments may
> > be forwarded or quoted, with due acknowledgement.  No
> > representation is
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> >
>