[postgis-users] Topology & Attributes

[Ofer Zilberstein]

Hi,

1. I advanced ...and I used the  topology.toTopoGeom() and now the relation
is populated.

2. I try to understand the following join

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

the second part of the join is clear -- comes from the relation table
however the first part - is not so clear

according to you - "parcelle is the polygon table with a topo column
containing the TopoGeometry object corresponding to the polygon" (you have
used here pe.parcelle - is it the table name ? )

so if in my case I have table 'department' with column 'topogeom' it would
look like

department d1 on (1,(d1.topogeom).id) = (r1.layer_id, r1.topogeo_id) ?


Ofer





On Mon, Feb 9, 2015 at 3:52 PM, Ofer Zilberstein <zilberstein.ofer at gmail.com
> wrote:

> 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
>>>>>
>>>>> _______________________________________________
>>>>> postgis-users mailing list
>>>>> postgis-users at lists.osgeo.org
>>>>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> postgis-users mailing list
>>>> postgis-users at lists.osgeo.org
>>>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>>>>
>>>
>>>
>>>
>>> --
>>>
>>> *Ofer Zilberstein*
>>>
>>>     Mobile: 972-544886873
>>>
>>>     Skype: ofer.zilberstein
>>>
>>>     Mail: zilberstein.ofer at gmail.com
>>>
>>> _______________________________________________
>>> postgis-users mailing list
>>> postgis-users at lists.osgeo.org
>>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>>>
>>
>>
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at lists.osgeo.org
>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>>
>
>
>
> --
>
> *Ofer Zilberstein*
>
>     Mobile: 972-544886873
>
>     Skype: ofer.zilberstein
>
>     Mail: zilberstein.ofer at gmail.com
>



-- 

*Ofer Zilberstein*

    Mobile: 972-544886873

    Skype: ofer.zilberstein

    Mail: zilberstein.ofer at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20150209/fd1c09dc/attachment.html>