[postgis-users] geometry types

[Karina Guardado]

Paul Ramsey escribió:
> On Tue, May 20, 2008 at 3:06 PM, Karina Guardado <kguardado at gmail.com> wrote:
>   
>> 1.from the 1.2.0 release of PostGIS there is support for "curve" /types/,
>> and initial support for the ISO SQL/MM suite of spatial database functions
>>     
>
> Yes, and you'll see some sparse documentation on these.  There is not
> full support of these types by all the functions, in fact very few of
> the functions will support them.
>
>   
>> 2.(from the list)We made a patch to add such new geometries to PostGIS.
>>
>> It implements TIN and POLYHEDRALSURFACE as described in
>> OGC SFS1.2 standard.
>> These geometries are specific MULTIPOLYGON that
>> describe 3D surfaces and 3D volumes.
>>
>> Currently, we got the following functions to work for 3D geometries:
>> - asEwkb
>> - asEwkt
>> - asGml
>> - asSvg (2D output only)
>> - asX3d.
>>
>> This last function enables exporting 3D geometries to the X3D format.
>> I also provide a patch for GEOS to implement the isValid function
>> for TIN and POLYHEDRALSURFACE. It checks if feature faces
>> are well connected and well oriented.
>>
>> So after reading this I feel confused if this geometry types are really
>> supported or not and I think it is not clear still for me, I would like to
>> know if there is an official documentation but updated with the last
>> geometry types supported by Postgis.
>>     
>
> This patch exists, as you found it on the list, but it has not been
> applied. I have some grave misaprehensions about the whole idea of
> modeling large structures like TIN as a single object. However, I am
> open to being forced into it by the Will of the People.
>
> Frank is right about LinearRing not being instantiable. I'd have to
> check and see but I believe there is no such thing as an instantiable
> Curve, just CurveString.  At least, a single curve isn't very useful
> as an object.
>
> P.
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>   
Thanks a lot for your help I really apreciate it. Just one more question 
in the web site of Postgis I found the following:

PostGIS follows the OpenGIS <http://www.opengis.org> "Simple Features 
Specification for SQL <http://www.opengis.org/docs/99-049.pdf>" and has 
been certified as compliant 
<http://www.postgis.org/files/opengis-certification.png> with the "Types 
and Functions".

At first reading I thought that Postgis support all of the features 
types specified in the OGC geometry model. But now as you explained me 
there is not support for all of this then could you please explain me 
about this compliant if this mean that you support only some but not 
necessary all and then you get the compliant.

In fact I'm doing a research in the university about the simple feature 
access and a comparison with the different spatial databases: 
postgres(postgis), oracle, mysql , db2 . So I need to be really clear 
respect to this because I don't want to publish something that is not 
true so I 'm really thanks for your help. When I finish the document I 
will sent you a copy.