I'm happy to hear this!!!
Please remember to use 3003 intead of 26591.
If I remember well there was some kind of offset error using the former.
It has been deprecated by EPSG on 16 Jan 2003 with this motivation:
"Associated with incorrect datum resulting in map projection longitude being
incompatible with prime meridian."
In fact 26591 uses this prime meridian:
PRIMEM["Rome",12.45233333333333,AUTHORITY["EPSG","8906"]]
while 3003 uses this one:
PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]]
The same applies for 3004 vs 26592.
Bye
Paolo Rizzi
> -----Messaggio originale-----
> Da: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] conto di
> Ludovico Bianchini
> Inviato: martedì 4 settembre 2007 17.51
> A: PostGIS Users Discussion
> Oggetto: Re: R: R: [postgis-users] precision of GeomFromTex,Transform
> and text functions
>
>
> Hi,
> you have centered the problem.
> With lon-lat couples situated in Italy it's work.
>
> The wrong longitude (I was convinced that 37 was in
> Italy) was born using java mapscript (a mapserver
> related component) to calculate a test value,
> converting the coords of a point in Treviso:
>
> x = 1752000f;
> y = 5062000f;
> point.setX(x);
> point.setY(y);
> point.project(new projectionObj("init=EPSG:26591"),
> new projectionObj("init=EPSG:4326"));
> point.toString();//37.13953463591601 45.66405322544534
>
> So I've now understood that the problem is not in
> postgis but in the epsg values that java mapscript
> uses in conversions. I'll search in this direction.
>
> Thank you very much for your helpful replies!!
>
>
> --- P.Rizzi Ag.Mobilità Ambiente
> <[EMAIL PROTECTED]> ha scritto:
>
> > There's no FROMWGS parameter, TOWGS is all that's
> > needed,
> > as far as I know.
> > Problem may be that the coordinates you are using
> > have
> > a longitude (37.xxxx) not inside Italy (actually
> > they apper to be
> > somewhere in southern Russia near the Georgia
> > border).
> > If you do the insert/select using coordinates like:
> > 9.13953463591601 45.66405322544534
> >
> > it should work as expected.
> >
> > Bye
> > Paolo Rizzi
> >
> >
> > > -----Messaggio originale-----
> > > Da: [EMAIL PROTECTED]
> > >
> >
> [mailto:[EMAIL PROTECTED]
> > conto di
> > > Ludovico Bianchini
> > > Inviato: martedì 4 settembre 2007 16.02
> > > A: PostGIS Users Discussion
> > > Oggetto: Re: R: [postgis-users] precision of
> > GeomFromTex,Transform and
> > > text functions
> > >
> > >
> > > Thanks for the suggestion, actually there were not
> > the
> > > toWGS parameter in spatial_ref_sys table.
> > >
> > > The situation seems to be a little better (here a
> > > sequence of insert-select:
> > > Insert:37.13953463591601 45.66405322544534
> > > Select:37.1321637582786 45.6647731135686
> > >
> > > Insert:37.1321637582786 45.6647731135686
> > > Select:37.1248123607135 45.6654908577754
> > >
> > > Insert:37.1248123607135 45.6654908577754
> > > Select:37.1174803443424 45.6662064695791), but the
> > > error is still too big.
> > >
> > > I have this question: is there a parameter
> > simmetric
> > > to TOWGS? If so the project library shall use
> > FROMWGS
> > > to convert from the gps system and TOWGS to
> > convert to
> > > the gps system.
> > > Sorry if the question is stupid, but I don't
> > > understand how to solve this problem (to convert
> > gps
> > > (SRID=4326) to West Gauss Boaga Italy Rome Monte
> > Mario
> > > (SRID=26591 or 3003).
> > >
> > > Any help will be very appreciated!!!
> > >
> > > Ludovico
> > >
> > >
> > > --- P.Rizzi Ag.Mobilità Ambiente
> > > <[EMAIL PROTECTED]> ha scritto:
> > >
> > > > I forget to mention the fact that inside the
> > PostGIS
> > > > spatial_ref_sys
> > > > table, TOWGS parameters are missing for
> > EPSG:26591
> > > > and for 3003 too.
> > > > So any transform will not be precise in any
> > case.
> > > > To add parameters for EPSG:3003, you can use the
> > > > following SQL
> > > > in any DB that you need to.
> > > >
> > > > Bye
> > > > Paolo Rizzi
> > > >
> > > >
> > > > ---
> > > > --- To add TOWGS parameters, if needed, to:
> > > > ---
> > > > --- EPSG 3003 : Monte Mario / Italy zone 1
> > > > ---
> > > > --- If parameters are already present, no change
> > > > will take place.
> > > > ---
> > > > UPDATE "spatial_ref_sys" SET
> > > > "srtext"='PROJCS["Monte Mario / Italy zone
> > > > 1",GEOGCS["Monte
> > > >
> > Mario",DATUM["Monte_Mario",SPHEROID["International
> > > >
> > >
> >
> 1924",6378388,297,AUTHORITY["EPSG","7022"]],TOWGS84[-104.1,-49
> > >
> >
> .1,-9.9,0.971,-2.917,0.714,-11.68],AUTHORITY["EPSG","6265"]],P
> > >
> >
> RIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.
> > >
> >
> 01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","
> > >
> >
> 4265"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_
> > >
> >
> of_origin",0],PARAMETER["central_meridian",9],PARAMETER["scale
> > >
> >
> _factor",0.9996],PARAMETER["false_easting",1500000],PARAMETER[
> > >
> >
> "false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],A
> > > UTHORITY["EPSG","3003"]]'
> > > > WHERE "srid"=3003 AND "auth_name"='EPSG' AND
> > > > "srtext" NOT LIKE '%TOWGS%';
> > > >
> > > > UPDATE "spatial_ref_sys" SET
> > > > "proj4text"='+proj=tmerc +lat_0=0 +lon_0=9
> > > > +k=0.999600 +x_0=1500000 +y_0=0 +ellps=intl
> > +units=m
> > > > +no_defs
> > > >
> > >
> >
> +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68'
> > > > WHERE "srid"=3003 AND "auth_name"='EPSG' AND
> > > > "proj4text" NOT LIKE '%towgs%';
> > > >
> > > >
> > > >
> > > >
> > > > > -----Messaggio originale-----
> > > > > Da:
> > [EMAIL PROTECTED]
> > > > >
> > > >
> > >
> >
> [mailto:[EMAIL PROTECTED]
> > > > conto di
> > > > > P.Rizzi Ag.Mobilità Ambiente
> > > > > Inviato: martedì 4 settembre 2007 11.25
> > > > > A: PostGIS Users Discussion
> > > > > Oggetto: R: [postgis-users] precision of
> > > > > GeomFromTex,Transform and text
> > > > > functions
> > > > >
> > > > >
> > > > > Probably it does not matter to you in this
> > case,
> > > > > but EPSG:26591 has been deprecated in favour
> > of
> > > > EPSG:3003.
> > > > > There is an error (can't remember what) in
> > 26591.
> > > > >
> > > > > Bye
> > > > > Paolo Rizzi
> > > > >
> > > > >
> > > > > > -----Messaggio originale-----
> > > > > > Da:
> > > > [EMAIL PROTECTED]
> > > > > >
> > > >
> > >
> >
> [mailto:[EMAIL PROTECTED]
> > > > conto di
> > > > > > Ludovico Bianchini
> > > > > > Inviato: lunedì 3 settembre 2007 21.39
> > > > > > A: postgis-users@postgis.refractions.net
> > > > > > Oggetto: [postgis-users] precision of
> > > > GeomFromTex,Transform and text
> > > > > > functions
> > > > > >
> > > > > >
> > > > > > Hi all,
> > > > > >
> > > > > > I'm using this postgis function:
> > > > > > - GeomFromText(text, int4) to create a
> > geometry
> > > > value
> > > > > > in 4326 spatial_ref_sys
> > > > > > - Transform(geometry, int4) to convert a
> > > > geometry from
> > > > > > 4326 to 26591 when I'm inserting a record
> > and to
> > > > > > convert 26591 to 4326 when I'm selecting
> > records
> > > > > > - text(geometry) to convert the geometry
> > column
> > > > in a
> > > > > > human-readable string
> > > > > >
> > > > > > The problem is that the operations are not
> > > > precise:
> > > > > > the value I obtain via
> > > > text(transorm(geom_column,
> > > > > > 4326)) is different from what I inserted via
> >
> >
> === message truncated ===
>
>
>
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