Thanks for that. Nice test case! FWIW, this runs fine in JTS. Hopefully someone on the GEOS side can take a look at this.

Roger André wrote:
Ok, here is the WKB.  Let me know if there are any problems with the file.
--

On Thu, Mar 26, 2009 at 8:57 AM, Martin Davis <[email protected] <mailto:[email protected]>> wrote:

    I don't think this can be the problem - a buffer of a linestring
    should still produce a polygon.

    This is probably a bug in the GEOS buffer algorithm.  It would
    help if you posted the WKB or WKB for the geometry.


    Chris Hermansen wrote:

        This sounds to me like you might be buffering a linestring and
        not a
        polygon.  Is that possible?  Ie are the countries represented as
        outlines (linestrings) rather than polygons?

        Roger André wrote:
            Hi All,

            I'm having some problems with features that are being
            returned from an
            ST_Buffer operation in PostGIS.  When I try to buffer the
            extents of
            Papua New Guinea, a large region in the middle of its
            extents is
            omitted.  You can see a visual representation of this at
            
http://lagerratrobe.blogspot.com/2009/03/problem-with-postgis-stbuffer.html

            If I just select the country itself, I get back all of the
            features
            that I'm expecting.  In the image I've posted above, the
            black area
            indicates the results of that query.

            I am using postgresql-8.3.5, and postgis-1.3.3.  My select
            statements
            is as follows:
               select name, Buffer(the_geom, .12) from coastlines where
            iso_3_code = 'PNG';

            I've tried this using both a free countries shapefile, as
            well as an
            ESRI one, and get the same results.  I'm a bit baffled,
            and unsure if
            I have a problem with both data sets, or in my query,
            or...?  If
            someone else has had a similar problem in the past, and
            can shed some
            light on it, I'd greatly appreciate it.

            Thanks in advance,

            Roger
            --
            
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-- Martin Davis
    Senior Technical Architect
    Refractions Research, Inc.
    (250) 383-3022


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Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022

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