[postgis-users] polygon creation

[Paul Ramsey]

Mostly no.
Arcs are kind of like LINESTRINGS only with an extra property, the
curvature betweent the vertices. So there are two issues around dealing
with ARCs. Firstly, storing the extra information about curvature. We do
not do that right now. A determined user could probably use the z
coordinate value as a storage location for that kind of information.
Secondly, doing exact mathematics with these curvy features. This is
something we are not even having an inkling of. 
P.

Cedric BERNIER wrote:
> 
> Hi all,
> 
> I need to create polygons made up circular arcs, is it possible to do this with postgis just like with
> ORACLE spatial ?
> 
> Jonathan Lowe a écrit :
> 
> > Chris,
> >
> > You were right. Updating to the proper version of the library file solved
> > the problem.
> >
> > Thanks very much,
> >
> > Jonathan
> >
> > ----------------------------------------------------------
> >
> > Is it possible that it is using an old library file, from when you perhaps
> > had postgres
> > 7.1 installed in the same directory? I would suggest this as a possibility
> > because the
> > ggeometry_consistent function is the first function defined in postgis.sql
> > which changed
> > in the library from 7.1 to 7.2. Check the date on the library file, and
> > ensure that it is
> > being copied correctly, and referenced correctly by the sql file.
> >
> > We have tested it on Solaris 6 on our SPARC  box, and it compiles,
> > installs, and functions
> > correctly, so it doesn't seem to be just a "Solaris bug".
> >
> > Chris
> >
> >
> >                       Jonathan Lowe
> >                                                To:       postgis-users at postgis.refractions.net
> >                       05/08/2002 04:09         cc:
> >                       PM                       From:     Jonathan Lowe/Oakland/IBM at IBMUS
> >                                                Subject:  Error running postgis.sql and libpostgis.so.0.7
> >
> >
> >
> >
> > Hello,
> >
> > An error is surfacing at the tail end of a PostGIS installation on a
> > Solaris 2.7 platform with PostgreSQL 7.2.1 and postgis 0.7.0.
> >
> > The following commands were successful:
> >       "make" (with the 72 switch set to "1")
> >       "make install" (with a perl script fix of some DOS carriage return
> > problems)
> >       "createlang plpgsql <yourdatabase>"
> >
> > However, the command "psql -f postgis.sql -d <yourdatabase>" results in the
> > following error:
> >
> > (...long list of various successful transactions...)
> > BEGIN
> > psql:postgis.sql:764: ERROR:  Can't find function ggeometry_consistent in
> > file /local3/pgsql/lib/contrib/libpostgis.so.0.7
> > BEGIN TRANSACTION;
> > (...remaining function creation statements within this BEGIN work block
> > aborted...)
> >
> > The path (/local3/pgsql/lib/contrib) and library file are correct and
> > exist.
> >
> > The statement in the postgis.sql file raising the error is the following:
> >
> > -------- 7.2 GiST support functions
> > create function ggeometry_consistent(opaque,GEOMETRY,int4) returns bool
> > as '/local3/pgsql/lib/contrib/libpostgis.so.0.7'   language 'C';
> >
> > Commenting out these lines and running the postgis.sql file again results
> > in a similar error for the next "create function" statement, which also
> > relies on the libpostgis.so.0.7 file.
> >
> > Other archived discussions refer to this lib file, but not in the context
> > of running postgis.sql.
> >
> > Any suggestions?
> >
> > Regards,
> >
> > Jonathan W. Lowe (jonathan at us.ibm.com)
> > Senior IT Specialist, IBM Data Management
> > --------------------------------------------------------------------------------------
> >
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