[postgis-users] Topology & Attributes

[Ofer Zilberstein]

Hi Nicolas,

1. I used  ST_CreateTopoGeo()  to build the topology (not the
topology.toTopoGeom()
as you mentioned )

When I look at the relation table its empty ? should I use
topology.toTopoGeom()
instead, and it will populate it ?

2. can you explain what the parentheses (special the 1, ...) part mean...

join pe.parcelle p1 on *(1, (p1.topo).id)* = (r1.layer_id, r1.topogeo_id)

Thanks in advanced ...

Ofer

On Mon, Feb 9, 2015 at 11:05 AM, Nicolas Ribot <nicolas.ribot at gmail.com>
wrote:

> Hi,
>
> As usual with SQL, there must be several other ways to perform the same
> query.
>
> As the edge view stores 2 faces id per row (left and right), I duplicated
> the joins to join both left_face and right face against the original
> polygon table (p1 and p2 aliases)
>
> Nicolas
>
> On 8 February 2015 at 21:57, Ofer Zilberstein <zilberstein.ofer at gmail.com>
> wrote:
>
>> Much Thanks,
>>
>> First I will try to understand the join that you did and then try to
>> implement it...
>>
>> Ofer
>>
>> On Sun, Feb 8, 2015 at 12:44 PM, Nicolas Ribot <nicolas.ribot at gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> When you build the topology, for instance with topology.toTopoGeom(),
>>> you get back a TopoGeometry object for each polygon added to the topology.
>>> This TopoGeometry is used to keep a link between your polygon object and
>>> all the topological elements composing it.
>>> The "relation" table inside the topo schema holding the topology
>>> contains the identifier of the topoGeometry object and the identifiers of
>>> topo elements composing the polygon.
>>>
>>> To get the right and left original polygons from the topology, you make
>>> a join between edge, relation and pg table:
>>> (topo_grass is the topo schema, parcelle is the polygon table with a
>>> topo column containing the TopoGeometry object corresponding to the
>>> polygon):
>>>
>>> select e.edge_id, e.left_face, e.right_face,
>>>   p1.id as left_id, p2.id as right_id
>>> from topo_grass.edge e
>>>   join topo_grass.relation r1 on r1.element_id = e.left_face
>>>   join pe.parcelle p1 on (1, (p1.topo).id) = (r1.layer_id, r1.topogeo_id)
>>>   join topo_grass.relation r2 on r2.element_id = e.right_face
>>>   join pe.parcelle p2 on (1, (p2.topo).id) = (r2.layer_id, r2.topogeo_id);
>>>
>>> Nicolas
>>>
>>>
>>>
>>> On 8 February 2015 at 10:29, Ofer Zilberstein <
>>> zilberstein.ofer at gmail.com> wrote:
>>>
>>>>
>>>> Hi,
>>>>
>>>> When you build topology from set of connected polygons, the original
>>>> polygon attributes are not part of the topology model. The model creates
>>>> MBR face for each original polygon.
>>>>
>>>> The edges hold the left & right faces.
>>>>
>>>> How or what is the right way to add to the edges the right and left
>>>> original polygons ?
>>>>
>>>> --
>>>>
>>>> *Ofer Zilberstein*
>>>>
>>>>     Mobile: 972-544886873
>>>>
>>>>     Skype: ofer.zilberstein
>>>>
>>>>     Mail: zilberstein.ofer at gmail.com
>>>>
>>>> _______________________________________________
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>>>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>>>>
>>>
>>>
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>>
>>
>>
>> --
>>
>> *Ofer Zilberstein*
>>
>>     Mobile: 972-544886873
>>
>>     Skype: ofer.zilberstein
>>
>>     Mail: zilberstein.ofer at gmail.com
>>
>> _______________________________________________
>> postgis-users mailing list
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>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>>
>
>
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-- 

*Ofer Zilberstein*

    Mobile: 972-544886873

    Skype: ofer.zilberstein

    Mail: zilberstein.ofer at gmail.com
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