[postgis-users] st_offsetcurve

[franco base]

Hi Sandro.
I make some new test.

1)
geom:

"0105000020E6100000030000000102000000020000008D383A2989B031400D12B11E01574940D32053AD91B0314078F4C42CFA56494001020000000200000042083BBCAAD11440D2A4DA35902242409EBC431F7DD114404A364DAB92224240010200000002000000A09DDE2E93C0E93F3EEEA26A82FB4340A047C9708EB5E93F9DA27A8EC5FB4340"

a --- st_OffsetCurve (geom, 10)  -----crash
b --- st_OffsetCurve  ( st_SimplifyPreserveTopology(geom,0.001), 10)
-----ok

 very low tolerance in st_simplify doesn't change the number of points and
the number of repeated points non consequential


2)
geom:
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

a --- st_OffsetCurve (geom, 10) -----crash
b --- st_OffsetCurve ( st_SimplifyPreserveTopology(geom,0.4), 10) -----crash
c --- st_OffsetCurve ( st_SimplifyPreserveTopology(geom,0.5), 10) -----ok

tolerance from 0.4 to 0.5 changes number of points from 25 to 23 but
doesn't change the number of repeated points non consequential

Final Surprise:
for all the 2 geometries
st_OffsetCurve (st_Transform (geom,4326), 10)
works but make a totally wrong geometry


f.b.










2013/10/4 Sandro Santilli <strk at keybit.net>

> On Fri, Oct 04, 2013 at 06:21:17PM +0200, franco base wrote:
> > Hi Sandro,
> > thank you for your answer,
> > I'll upgrade my GEOS, but I work for a Public Administration and this
> > process is slow.
> >
> > So I have Isolated the geometry wher St_OffsetCurve crash.
> > There are two type of geometries:
> >
> > 1) Geometry with repeated points. I can solve the problem using:
> >  St_OffsetCurve (ST_RemoveRepeatedPoints(geom), 10)
> >
> >
> > 2) Geomtery with repeated points but non consequential (see the .jpg)
> >
> > The geometry is
> >
> "0102000020BB0B000013000000F49BB3FCAA3037413033606B9C3253412FD60B7D61303741EDE29F4E9B3253416842DD0745303741DD30E3C89A3253417776B8621830374149B42AE399325341EDC13D130430374122AE490A983253415FAF500FFC2F37410A84A0DD943253415500A09BFE2F3741D62BEB178532534166ECD670FF2F3741F01372E67A3253417713ABF605303741CE2AF9FC77325341BBA13CB0283037415C422E6F713253410B10133F2E303741256D85F770325341A024E9F33330374115D50563713253414B75A9D4363037419868B9B8723253410DFDE549353037415AF87C3177325341CAF46320303037411170B9E88F325341536848BF2F30374135F86EA19532534180088DD2363037417D62C985983253416842DD0745303741DD30E3C89A3253412FD60B7D61303741EDE29F4E9B325341"
>
> > You think that GEOS-3.3.9, or 3.4.2. solve this problem or this is a
> "bug"
> > of the St_OffsetCurve.
>
> I can tell you it's _not_ fixed in 3.4.2 :(
> Could you file a ticket please ?
> Add the RemoveRepeatedPoints trick, is useful!
>
> --strk;
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