<div dir="ltr"><div><div><div>Thank you Hermann,<br><br></div>just did a quick comparison of the results after using invproj, seem to have the same result.<br></div>regards,<br></div>Szilard<br><br></div><div class="gmail_extra">
<br><br><div class="gmail_quote">On 24 October 2013 16:52, Hermann Peifer <span dir="ltr"><<a href="mailto:peifer@gmx.eu" target="_blank">peifer@gmx.eu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
On 2013-10-24 6:46, Szilard Albert wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
The task is to convert UTM Zone 53 XY coordinates into Lat/Lon<br>
coordinates, keeping datum.<br>
</blockquote>
<br>
For this task, you don't really need cs2cs. proj -I or invproj can be used. See below.<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
I am using:<br>
<br>
*cs2cs -W2 +proj=utm +zone=53 +south +datum=WGS84 +to +proj=latlong<br>
+datum=WGS84<br>
669734.6 7607027.2<br>
136d38'24.07"E 21d37'54.60"S 0.000*<br>
<br>
getting a result that seems fine.<br>
<br>
However, the following issues arise:<br>
<br>
1. My input data is on the GDA94 datum. When I try +datum=GDA94 (or<br>
GDA), I get<br>
/<cs2cs>:<br>
projection initialization failure<br>
cause: unknown elliptical parameter name./<br>
</blockquote>
<br>
proj -ld (or cs2cs -ld) gives the list of known datums. GDA or GDA94 are not mentioned there. However, you do not have to worry, as you anyway want to keep the datum.<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Am I safe using WGS84, since the difference between these 2 datums is<br>
less than 1 m? (<a href="http://www.geoproject.com.au/gda.faq.html" target="_blank">http://www.geoproject.com.au/<u></u>gda.faq.html</a>).<br>
<br>
2. I have heaps of other parameters of my input data - as below - should<br>
any of these be incorporated in my command,<br>
or datum and zone are enough?<br>
<br>
Datum GDA94<br>
Spheroid GRS80<br>
Semi-major axis<br>
Projection UTM MGA Z 53<br>
Central meridian 135 E<br>
False E/N, Scale factor 0.9996 etc<br>
<br>
</blockquote>
<br>
I would simply use: invproj -W2 +proj=utm +zone=53 +south +ellps=GRS80<br>
<br>
Other parameters like central meridian, scale factor, etc. do not need to be specified explicitly. They are implied through +proj=utm and +zone=53.<span class="HOEnZb"><font color="#888888"><br>
<br>
<br>
Hermann<br>
<br>
</font></span></blockquote></div><br></div>