Thanks Simon. Your examples help. Let us know if you write that blog article.
Larry On Fri, Feb 13, 2009 at 10:59 PM, Simon Greener <[email protected]>wrote: > Larry, > > > I'm looking at the following comment in your code. I understand the > concept > > of boundary-defined rings, but I'm a little confused by "adds them as > > interior LinearRings to other interior rings present in that Polygon." > > > > * In ArcSDE polygon-holes touching an exterior/interior boundary in a > single point is formed > > * by a self-closing "loop" in that exterior/interior boundary. This is > not SFS/JTS-valid. > > > > * This converter removes such boundary-defined "rings" from the outer > and interior rings of > > * a JTS Polygon, and adds them as interior LinearRings to other > interior rings present > > * in that Polygon. > > > > This sounds like an important special case, but I've never encountered > it. > > Can you give an example to make it clearer? > > ESRI's ArcSDE existed before ESRI did and also before the OGC SFS standard > existed. In the original SDBE polygons were allowed to have inversions and > exversions. An inversion is where the interior boundary touch a vertex of > the outer boundary. An inversion touching a vertex of the outer shell is > considered part of the outer shell. SDBE also allowed exverted polygons (a > form of a bow tie). I have attached some images to help make this clearer. > (I have been intending on writing a blog article on this for a few years - > including how to handle them in Oracle - and have not gotten around to it. > Perhaps it is about time I did. > > regards > Simon > -- > SpatialDB Advice and Design, Solutions Architecture and Programming, > Oracle Database 10g Administrator Certified Associate; Oracle Database 10g > SQL Certified Professional > Oracle Spatial, SQL Server, PostGIS, MySQL, ArcSDE, Manifold GIS, FME, > Radius Topology and Studio Specialist. > 39 Cliff View Drive, Allens Rivulet, 7150, Tasmania, Australia. > Website: www.spatialdbadvisor.com > Email: [email protected] > Voice: +613 9016 3910 > Mobile: +61 418 396391 > Skype: sggreener > Longitude: 147.20515 (147° 12' 18" E) > Latitude: -43.01530 (43° 00' 55" S) > NAC:W80CK 7SWP3 > _______________________________________________ > jts-devel mailing list > [email protected] > http://lists.refractions.net/mailman/listinfo/jts-devel > > -- http://amusingprogrammer.blogspot.com/
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