[geos-devel] BUG: relate(g1,g2) crashes with GEOMETRYCOLLECTION?

[Paul Ramsey]

Nice. Overlaps is not what I thought it was. What is the test for 
interior(A) intersects interior(B)?
P.

On Tuesday, April 8, 2003, at 01:57 PM, Martin Davis wrote:

> Nope - if you look at the spec it clearly spells out that A and B 
> overlap *only* if A intersects exterior(B) or vice-versa.  They 
> clearly intended the answer to be FALSE if the geometries were the 
> same.
>
> Martin Davis, Senior Technical Architect
> Vivid Solutions Inc.
> Suite #1A-2328 Government Street   Victoria, B.C.   V8T 5G5
> Phone: (250) 385 6040    Fax: (250) 385 6046
> EMail: mbdavis at vividsolutions.com  Web: www.vividsolutions.com
>
>
>> -----Original Message-----
>> From: Martin Davis
>> Sent: Tuesday, April 08, 2003 1:52 PM
>> To: GEOS Development List
>> Subject: RE: [geos-devel] BUG: relate(g1,g2) crashes with
>> GEOMETRYCOLLECTION?
>>
>>
>> Yep, overlaps(G,G) = false according to the OGC spec.  This
>> may be a bit counter-intuitive.  Not sure what the rationale
>> behind this decision was.
>>
>> I usually use A.relate(B, "T********") to determine if things
>> overlap "properly".
>>
>> Martin Davis, Senior Technical Architect
>> Vivid Solutions Inc.
>> Suite #1A-2328 Government Street   Victoria, B.C.   V8T 5G5
>> Phone: (250) 385 6040    Fax: (250) 385 6046
>> EMail: mbdavis at vividsolutions.com  Web: www.vividsolutions.com
>>
>>
>>> -----Original Message-----
>>> From: David Blasby [mailto:dblasby at refractions.net]
>>> Sent: Tuesday, April 08, 2003 1:43 PM
>>> To: GEOS Development List
>>> Subject: Re: [geos-devel] BUG: relate(g1,g2) crashes with
>>> GEOMETRYCOLLECTION?
>>>
>>>
>>> Martin Davis wrote:
>>>
>>>> Yep.  Neither GEOS nor JTS support GeometryCollections as
>>> arguments to relate.  This is partly because the semantics
>>> aren't very well defined, and partly because the obvious
>>> semantics [ X.relate(GC) = X.relate(union(GC.components) ]
>>> would make the operation non-robust.
>>>>
>>>> That said, we or you could always implement the above
>>> semantics fairly easily...
>>>>
>>> Its unfortunate that the spec doesnt tell you what to do in
>>> the case of
>>> GEOMETRYCOLLECTIONs.
>>>
>>> I've also noticed that overlaps(g,g) is FALSE!
>>>
>>> dave
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> geos-devel mailing list
>>> geos-devel at geos.refractions.net
>>> http://geos.refractions.net/mailman/listinfo/geos-devel
>>>
>>
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>
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      Paul Ramsey
      Refractions Research
      Email: pramsey at refractions.net
      Phone: (250) 885-0632