Hi Uwe, Stefan, OpenJUMP (JTS) is right, this MultiPolygon is not OGC conform
Here is the citation : Multipolygon 2. The Boundaries of any 2 Polygons that are elements of a MultiPolygon may not ‘cross’ and may touch at only a finite number of points. (Note that crossing is prevented by assertion 1 above). Don't ask me why, I've always thought it is strange that lines can share their boundaries in a MultiLineString and polygons cannot share an edge in a MultiPolygon, but it's a well established rule that JTS follows. Michaël > Hi Uwe, > > I am not sure I would call it a bug. OJ, should (try to) create data > that are OGC conform, but in this case it doesn't. Which means, the case > needs special treatment, but this is not implemented. > > That the multi-polygon causes an error is with the OGS SF specification > = correct. However, that the geometry collection does not cause an error > should be correct aw well, because there is, I believe, nothing said > about geometry collections and their validity. Geometry collections > should be allowed to have any type of geometries in what ever way they > are drawn - like a "container". If we would check geometry collections > for their validity it may be that people cannot store anymore the data > they have. Hence, checking should be optional. > > But I guess here, Michael M. knows probably more about OGC conformance? > I'll also cc to JTS list. > > cheers, > stefan > > PS: the Multi-polygon: > > MULTIPOLYGON ((( > 80 125, > 80 241, > 175 241, > 175 125, > 80 125 > )), (( > 175 125, > 175 241, > 263 241, > 263 125, > 175 125 > ))) > > Am 08.04.13 09:48, schrieb Uwe Dalluege: >> Hi Stefan, >> >> I am afraid I do not understand :-( >> Do you think this is a bug in OJ? >> The multipolygon causes an error >> the geometrycollection not. >> >> Is this behaviour OGC-conform (simpel features...)? >> What do you think? >> >> uwe >> >> Am 08.04.2013 16:36, schrieb Stefan Steiniger: >>> Hi, >>> >>> so - well the situation is not so nice, as it should be valid. However, >>> the JTS TestBuilder says the Multi-Polgyon is invalid because of >>> "Self-intersection at or near point (175.0, 125.0, NaN)" >>> >>> Same message appears when you try to add it as a new feature. >>> >>> maybe you can make it valid before by running a zero-buffer over it? >>> >>> stefan >>> >>> Am 08.04.13 07:30, schrieb Uwe Dalluege: >>>> Hi, >>>> >>>> if you put a third geometrie to the two polygons, >>>> for instance a linestring, and combine them >>>> you will receive a geometrycollection >>>> and not a multipolygon. >>>> >>>> The geometrycollection causes *no* errors >>>> but the multipolygon. >>>> >>>> Uwe >>>> >>>> >>>> Am 08.04.2013 12:05, schrieb Uwe Dalluege: >>>>> Hi, >>>>> >>>>> I get the error: >>>>> >>>>> "The new geometry is invalid. Cancelled." >>>>> and I am not shure whether this error is correct. >>>>> >>>>> 1. Switch "Snap to vertices" option. >>>>> >>>>> 2. Draw a rectangle. >>>>> >>>>> 3. Draw a second rectangle with two identical >>>>> vertices from the first rectangle (with snap). >>>>> >>>>> 4. Select the two rectangles and >>>>> "Combine Selected features" >>>>> >>>>> 5. Try to move this multipolygon with >>>>> "Move Selected Items Tool". >>>>> >>>>> 6. The error appears >>>>> "The new geometry is invalid. Cancelled." >>>>> >>>>> 7. The QA>Validate Selected Layers... >>>>> causes a self-intersection in *one* point. >>>>> >>>>> Is this a bug in OJ (a precision-problem) >>>>> or is the new geometry really invalide? >>>>> >>>>> Uwe >>>>> >>>>> ------------------------------------------------------------------------------ >>>>> >>>>> Minimize network downtime and maximize team effectiveness. >>>>> Reduce network management and security costs.Learn how to hire >>>>> the most talented Cisco Certified professionals. 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Visit the >>> Employer Resources Portal >>> http://www.cisco.com/web/learning/employer_resources/index.html >>> _______________________________________________ >>> Jump-pilot-devel mailing list >>> Jump-pilot-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >>> > ------------------------------------------------------------------------------ > Minimize network downtime and maximize team effectiveness. > Reduce network management and security costs.Learn how to hire > the most talented Cisco Certified professionals. Visit the > Employer Resources Portal > http://www.cisco.com/web/learning/employer_resources/index.html > _______________________________________________ > Jump-pilot-devel mailing list > Jump-pilot-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel > > ------------------------------------------------------------------------------ Minimize network downtime and maximize team effectiveness. Reduce network management and security costs.Learn how to hire the most talented Cisco Certified professionals. Visit the Employer Resources Portal http://www.cisco.com/web/learning/employer_resources/index.html _______________________________________________ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
