<div dir="ltr"><span style="font-family:arial,sans-serif;font-size:13px">Roma 1940 Gauss Boaga is different in that it as a different central meridian.</span><br><div><span style="font-family:arial,sans-serif;font-size:13px">The other two are different definitions of the same datum, but in 3003 there re the average transformation parameters. That's why it works better then </span><span style="font-family:arial,sans-serif;font-size:13px">102094.</span></div>
<div><span style="font-family:arial,sans-serif;font-size:13px">In the previous email I inverted the two.</span></div><div><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div><div><span style="font-family:arial,sans-serif;font-size:13px">giovanni</span></div>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/11/7 Paolo <span dir="ltr"><<a href="mailto:e-paul@tiscali.it" target="_blank">e-paul@tiscali.it</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
Yes, actuallyI am reprojecting rasters from Gauss Boaga Roma 40
Monte Mario zone 2 to ED50UTM33.<br>
Errors are huge if I use 102092, but they are very small using
3004.<br>
<br>
Further research lead me to discover even more, appearingly
identical, reference systems:<br>
- Monte Mario Italy 2.prj (codice EPSG 3004);<br>
- Monte Mario (Rome) Italy 2.prj (codice EPSG 26592);<br>
- Roma 1940 Gauss Boaga Est.prj (codice EPSG 102094),<br>
<br>
This is even more confusing, and will require some more studying.<br>
<br>
Regards,<br>
Paolo<br>
<br>
<div>Il 07/11/2013 10:37, G. Allegri ha
scritto:<br>
</div><div><div class="h5">
<blockquote type="cite">
<p dir="ltr">As you can see, 102092 has the average transformation
parameters to WGS84, which brings some more precision during
datum transformation. I suppose you're reprojecting the data to
some different CRS. </p>
<p dir="ltr">giovanni</p>
<div class="gmail_quote">Il 07/nov/2013 08:33 "Paolo" <<a href="mailto:e-paul@tiscali.it" target="_blank">e-paul@tiscali.it</a>>
ha scritto:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> Oops... I forgot the
most important part in my first post. Here are the
edfinitions:<br>
<br>
EPSG 3004 - Monte Mario / Italy zone 2:<br>
+proj=tmerc +lat_0=0 +lon_0=15 +k=0.9996 +x_0=2520000 +y_0=0
+ellps=intl
+towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68
+units=m +no_defs<br>
<br>
EPSG 102092 - Monte_Mario_Italy_2:<br>
+proj=tmerc +lat_0=0 +lon_0=15 +k=0.9996 +x_0=2520000 +y_0=0
+ellps=intl +units=m +no_defs<br>
<br>
3004 works well with my data, while 102092 does not.<br>
There appears to be a relatively large shift, in the order
of tens or hundreds meters,monstly along the north - south
direction.<br>
<br>
Thanks<br>
Paolo<br>
<br>
<br>
<br>
<div>Il 07/11/2013 00:47, G. Allegri ha scritto:<br>
</div>
<blockquote type="cite">
<div dir="ltr">In QGIS they appear having the same
definition, Could you paste the 102092 definition that
you have?
<div><br>
</div>
<div>giovanni</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">2013/11/6 Paolo <span dir="ltr"><<a href="mailto:e-paul@tiscali.it" target="_blank">e-paul@tiscali.it</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello,<br>
I am a relatively recent QGIS user. I am at the
moment using version 2.0 - Dufour.<br>
I would like to ask a simple question about two
different datums I am experiencing problems with.<br>
They are: EPSG 102092 and EPSG 3004.<br>
Accordinf to my (short) research, they are supposed
to be exactly the same datum, but the definitions in
QGIS are different.<br>
If I use 3004, the specific data set I'm using will
overlap properly with the other datasets, but it
will not if I use 102092.<br>
Can anybody help me getting a better understanding
of this behaviour?<br>
Thanks<span><font color="#888888"><br>
Paolo<br>
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</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
Giovanni Allegri<br>
<a href="http://about.me/giovanniallegri" target="_blank">http://about.me/giovanniallegri</a><br>
blog: <a href="http://blog.spaziogis.it" target="_blank">http://blog.spaziogis.it</a><br>
GEO+ geomatica in Italia <a href="http://bit.ly/GEOplus" target="_blank">http://bit.ly/GEOplus</a>
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</blockquote>
<br>
</div>
</blockquote>
</div>
</blockquote>
<br>
</div></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br>Giovanni Allegri<br><a href="http://about.me/giovanniallegri" target="_blank">http://about.me/giovanniallegri</a><br>blog: <a href="http://blog.spaziogis.it" target="_blank">http://blog.spaziogis.it</a><br>
GEO+ geomatica in Italia <a href="http://bit.ly/GEOplus" target="_blank">http://bit.ly/GEOplus</a>
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