[postgis-users] postgis 1.4 and curves

[mario at geosar.ch]

Hi,
the geometry is :
GeomFromText('COMPOUNDCURVE((723702.522 121248.15,723892.918
121297.093),(723892.918 121297.093,724230.191
121220.96),CIRCULARSTRING(724230.191 121220.96,724268.27
121144.826,724251.951 121025.188))')

Then try:
select st_astext( st_linetocurve(
st_curvetoline(GeomFromText('COMPOUNDCURVE((723702.522 121248.15,723892.918
121297.093),(723892.918 121297.093,724230.191
121220.96),CIRCULARSTRING(724230.191 121220.96,724268.27
121144.826,724251.951 121025.188))')) ) )

I obtain:
COMPOUNDCURVE((723702.522 121248.15,723892.918 121297.093,724230.191
121220.96),CIRCULARSTRING(724230.191 121220.96,724271.107624879
121128.220456049,724253.605225062 121028.378284577),(724253.605225062
121028.378284577,724251.951 121025.188))

After the arc another line is added and the points of the arc are different.

Thanks
Mario





-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Mark
Cave-Ayland
Sent: mercoledì, 29. luglio 2009 13:04
To: PostGIS Users Discussion
Subject: Re: [postgis-users] postgis 1.4 and curves

Mario Jurcevic wrote:

> Hello,
> postgis 1.4 has suport for curved polygons that is great, but not the
> functions like st_union,st_intersection.
> Is planned that this functions will support curves?
> I tried a workarround transofrming curves to lines with:
> set_union( st_linetocurve( st_curvetoline(the_geom) ) ) but the resulting
> geometry has arcs modified in a strange
> way, it always add a little segment at the beginning or end of the
original
> curve.
> 
> Maybe a bug in st_linetocurve?
> 
> Thanks
> 
> Mario

Hi Mario,

The ST_LineToCurve/ST_CurveToLine functions have had a lot of work done 
on them for 1.4, however we can't really help you much without a test 
case :)


ATB,

Mark.

-- 
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
http://www.siriusit.co.uk
t: +44 870 608 0063
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