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List:       postgis-users
Subject:    Re: [postgis-users] Projection problem
From:       Jaime Fiers <jaime.fiers () gmail ! com>
Date:       2010-07-24 11:13:45
Message-ID: AANLkTik2j8mLKklj1EYIFNBQepuD_BlgEVknsbStpyyb () mail ! gmail ! com
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Hi Ralf.

You gave me the correct way.  Thanks a lot.

Finally, I used a similar SQL, with the double transformation you said, and
result is good:


CREATE OR REPLACE VIEW vista_23030 AS
 SELECT "GID", transform_geometry(transform( geom, 4326), '+proj=longlat
+ellps=WGS84 +datum=WGS84 +no_defs '::text, '+proj=utm +ellps=intl +zone=30
+units=m +towgs84=-131,-100.3,-163.4,-1.244,-0.02,-1.14 +no_defs'::text,
23030)
 AS geom
   FROM capa_25830;

Regards
Jaime

2010/7/23 Ralf Suhr <Ralf.Suhr@itc-halle.de>

> Hi Jaime,
>
> to get transformation with towgs84 parameter working you have to use wgs84
> ellipsoid. Transform from ETRS89 to wgs84 and second from wgs84 to ED50.
>
> ST_Transform(ST_Transform( 25830_geom, 4326), 23030)
>
> Gr
> Ralf
>
> Am Freitag 23 Juli 2010, 08:42:39 schrieb Jaime Fiers:
> > Hello guys
> >
> > I hava a "little" problem with Postgis projection.
> >
> > I need get a reprojected view.  Original data layer is in SRS=25830
> (ETRS89
> > UTM30) and view in SRS=23030 (ED50 UTM30)
> >
> > I try this:
> >
> > CREATE OR REPLACE VIEW vista_23030 AS
> >  SELECT id, transform_geometry("GEOMETRY", '+proj=utm +zone=30
> +ellps=GRS80
> > +units=m +no_defs
> >
> +towgs84=131.0,100.3,163.4,1.2439999999999989,0.01999999999999998,1.1439999
> > 999999988,-9.39 '::text,
> >  '+proj=utm +zone=30 +ellps=intl +units=m +nadgrids +no_defs'::text,
> 23030)
> > AS "GEOMETRY"
> >    FROM capa_25830;
> >
> > (If we do not include "+nadgrids" we don't get anything, but that is not
> a
> > problem).
> > I always get a +-90 meter error.
> >
> > Can anybody help me.
> >
> > Thanks in advance
> _______________________________________________
> postgis-users mailing list
> postgis-users@postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
>

[Attachment #5 (text/html)]

Hi Ralf.<br><br>You gave me the correct way.  Thanks a lot.<br><br>Finally, I used a \
similar SQL, with the double transformation you said, and result is good:<br><br><br> \
CREATE OR REPLACE VIEW vista_23030 AS <br>  SELECT &quot;GID&quot;, \
transform_geometry(transform( geom, 4326), &#39;+proj=longlat +ellps=WGS84 \
+datum=WGS84 +no_defs &#39;::text, &#39;+proj=utm +ellps=intl +zone=30 +units=m
+towgs84=-131,-100.3,-163.4,-1.244,-0.02,-1.14 +no_defs&#39;::text, 23030)<br>
 AS geom<br>
   FROM capa_25830;<br><br>Regards<br>Jaime<br><br><div class="gmail_quote">2010/7/23 \
Ralf Suhr <span dir="ltr">&lt;<a \
href="mailto:Ralf.Suhr@itc-halle.de">Ralf.Suhr@itc-halle.de</a>&gt;</span><br><blockquote \
class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, \
204, 204); padding-left: 1ex;"> Hi Jaime,<br>
<br>
to get transformation with towgs84 parameter working you have to use wgs84<br>
ellipsoid. Transform from ETRS89 to wgs84 and second from wgs84 to ED50.<br>
<br>
ST_Transform(ST_Transform( 25830_geom, 4326), 23030)<br>
<br>
Gr<br>
Ralf<br>
<br>
Am Freitag 23 Juli 2010, 08:42:39 schrieb Jaime Fiers:<br>
<div><div></div><div class="h5">&gt; Hello guys<br>
&gt;<br>
&gt; I hava a &quot;little&quot; problem with Postgis projection.<br>
&gt;<br>
&gt; I need get a reprojected view.  Original data layer is in SRS=25830 (ETRS89<br>
&gt; UTM30) and view in SRS=23030 (ED50 UTM30)<br>
&gt;<br>
&gt; I try this:<br>
&gt;<br>
&gt; CREATE OR REPLACE VIEW vista_23030 AS<br>
&gt;  SELECT id, transform_geometry(&quot;GEOMETRY&quot;, &#39;+proj=utm +zone=30 \
+ellps=GRS80<br> &gt; +units=m +no_defs<br>
&gt; +towgs84=131.0,100.3,163.4,1.2439999999999989,0.01999999999999998,1.1439999<br>
&gt; 999999988,-9.39 &#39;::text,<br>
&gt;  &#39;+proj=utm +zone=30 +ellps=intl +units=m +nadgrids +no_defs&#39;::text, \
23030)<br> &gt; AS &quot;GEOMETRY&quot;<br>
&gt;    FROM capa_25830;<br>
&gt;<br>
&gt; (If we do not include &quot;+nadgrids&quot; we don&#39;t get anything, but that \
is not a<br> &gt; problem).<br>
&gt; I always get a +-90 meter error.<br>
&gt;<br>
&gt; Can anybody help me.<br>
&gt;<br>
&gt; Thanks in advance<br>
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target="_blank">http://postgis.refractions.net/mailman/listinfo/postgis-users</a><br> \
</blockquote></div><br>



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