[postgis-devel] How are these concepts managed in PostGIS?

[Jorge Arévalo]

On Mon, Aug 30, 2010 at 6:42 PM, Martin Davis <mbdavis at refractions.net> wrote:
> Tolerance in the way that Oracle uses it is not supporting in PostGIS.
>  Instead, functions such as spatial predicates and overlay operations (eg
> intersection) are computed using the full precision of the DP floating point
> numbers.  (Intternally GEOS does support the concept of a user-defined
> precision model, but this isn't exposed in PostGIS).
>
> I'll let someone else speak to M-value support.

Ok, thanks for responde Martin.


>
> Jorge Arévalo wrote:
>>
>> Hi,
>>
>> I'd like to know if these two concepts are taken into account in
>> PostGIS, and where to find information on how are they managed. They
>> are concepts used in Oracle Spatial:
>>
>> - Tolerance (distance that two points can be apart and still be
>> considered the same):
>>
>> http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28400/sdo_intro.htm#i884589
>>
>> - Unit of measurement support (particularly, creating an user-defined
>> unit of measurement):
>>
>> http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28400/sdo_objrelschema.htm#i1010145
>>
>> I'm not finding this information in PostGIS manual
>> (http://postgis.refractions.net/documentation/manual-svn/).
>>
>> Many thanks in advance, and best regards,
>>
>> --
>> Jorge Arévalo
>> Internet & Mobilty Division, DEIMOS
>> jorge.arevalo at deimos-space.com
>> http://mobility.grupodeimos.com/
>> http://gis4free.wordpress.com
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>>
>>
>
> --
> Martin Davis
> Senior Technical Architect
> Refractions Research, Inc.
> (250) 383-3022
>
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-- 
Jorge Arévalo
Internet & Mobilty Division, DEIMOS
jorge.arevalo at deimos-space.com
http://mobility.grupodeimos.com/
http://gis4free.wordpress.com