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<small><font size="+1"><small>I had problems a while back using AGD66,
AGD84 and GDA94.</small></font> </small>Like you, Brett, I wasn't
getting the expected offset between data imported as AGD66/84 and
GDA94. I am going from a distant memory so just ignore anything I say
if it doesn't make sense, but there could be two issues here.<br>
<br>
1) I think Proj4 only defines a CRS if it doesn't have conflicting
definitions. There are multiple ways to define the towgs84 parameters
for AGD66 and AGD84, so Proj4 doesn't include any of them. If you look
at the Proj4 strings (in the QGIS CRS chooser) for say AGD66/Z55 and
AGD84/Z55 they are the same (
<style type="text/css">p, li { white-space: pre-wrap; }</style>+proj=utm
+zone=55 +south +ellps=aust_SA +units=m +no_defs ). From memory, I
think I got around this by choosing a towgs84 definition that I liked
and then just used that as a custom CRS. You could use the custom CRS
generated when importing a MapInfo file for example.<br>
<br>
2) About 6 months ago a problem with the custom database structure was
fixed. This was preventing custom CRS definitions from being used. If
you have been using QGIS for a while it might be worth deleting the
custom qgis.db (/.qgis/qgis.db in your home directory on Linux) so that
Qgis recreates it. This could be the reason layers are defaulting to
WGS84.<br>
<br>
Roland<br>
<br>
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<div class="moz-signature">-- <br>
<strong><font face="Arial" color="#000080">ROLAND HILL</font></strong><br>
<strong><font face="Arial" color="#000080" size="2">Director</font></strong><br>
<strong><font face="Arial" color="#000080" size="2">Four Winds
Technology Pty Ltd</font></strong><br>
<strong><font face="Arial" color="#000080" size="2">Ph/Fax : +61
(0)2 6366 9425</font></strong><br>
<strong><font face="Arial" color="#000080" size="2">Mobile :
+61 (0)41 880 7472</font></strong><br>
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href="mailto:Roland.Hill@fourwindstechnology.com.au">Roland.Hill@fourwindstechnology.com.au</a></font></strong>
<br>
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On 21/09/10 10:21, Brett Adams wrote:
<blockquote cite="mid:4C97FA8E.1060202@gmail.com" type="cite"> Enabling
"On-the-fly projection" does make a small difference but the offset
should be approx 195-200m. I get 12m.
<br>
<br>
<br>
On 21/09/2010 4:42 AM, Jürgen E. Fischer wrote:
<br>
<blockquote type="cite">Hi Brett,
<br>
<br>
On Mon, 20. Sep 2010 at 22:11:17 +0800, Brett Adams wrote:
<br>
<blockquote type="cite">Actually, this is worse than I thought.
QGIS is not recognising AGD84 or
<br>
GDA94. The data comes in but isn't attributed a CRS so defaults to
WGS84.
<br>
If you import the text file as AGD84, then again as GDA94, there should
be
<br>
approx 195m separation. QGIS plots them in exactly the same place.
<br>
</blockquote>
But have have set a specific projection in your project properties and
enabled
<br>
on-the-fly projection? Otherwise QGIS won't reproject anything.
<br>
<br>
Jürgen
<br>
<br>
</blockquote>
<br>
<br>
</blockquote>
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