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
>>>>
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