[postgis-devel] Re: Q3C

[Martin Davis]

Er - of course, I remember this.  Those listening at home might not have 
heard of it though...   8^)  The context switch from indexing to 
geometry functions might have thrown them off the scent a bit too...

Paul Ramsey wrote:
> We figured this out, remember? We're converting to geocentric
> coordinates for the purpose of indexing.
>
> P
>
> On Wed, Mar 18, 2009 at 4:16 PM, Martin Davis <mbdavis at refractions.net> wrote:
>   
>> Hmmm.
>>
>> How will you handle indexing geometries which cross the dateline (which
>> includes crossing the poles)?
>>
>> Paul Ramsey wrote:
>>     
>>> On Wed, Mar 18, 2009 at 2:41 PM, Paul Ramsey <pramsey at opengeo.org> wrote:
>>>
>>>       
>>>> I'm having a grand time thinking about what the appropriate return
>>>> value of geography::geometry is :)
>>>>
>>>>         
>>> My current thought is an automagical planar projection into an
>>> appropriate UTM zone or polar stereographic system, based on the
>>> centroid of the feature. With the extra complication of first looking
>>> into the projection cache to see what the last projection used was,
>>> and if it's close enough, using that. Hopefully that way, in the case
>>> of st_function(geog1, geog2) the two arguments would be both cast into
>>> the same plane. This would magically allow the geography module to
>>> make use of all the geometry functions, and only break for really
>>> large objects that exceed our chosen planar areas.
>>>
>>> P.
>>> _______________________________________________
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>>>
>>>
>>>       
>> --
>> Martin Davis
>> Senior Technical Architect
>> Refractions Research, Inc.
>> (250) 383-3022
>>
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>>
>>     
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>   

-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022