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
<<attachment: BowTie.png>>
<<attachment: InvertedPolygon.png>>
<<attachment: exverted.png>>
<<attachment: DoubleInverted.png>>
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