[postgis-devel] [postgis-users] linking 2 topogeometries of different nature

[Rémi Cura]

I wrote down all the cases and here is the conclusion :

*When looking for topogeom B related to topogeom A, we should get all
elements of B which may be impacted by a change in A.*
This definition of relation is much more clear and precise.

So with this new definition,

getting puntal/lineal/areal impacted by a change on a point is to take all
node impacted (one) / all edge impacted by this node / all faces impacted
by all edges impacted by the node.

Same for a change in lineal or in areal.

I'll re-code in this way.

Cheers,

Rémi-C


2013/10/23 Rémi Cura <remi.cura at gmail.com>

> Hmm it can't work,
>
> please do not consider the previous message, i'm doing changes.
>
> Cheers,
> Rémi-C
>
>
> 2013/10/23 Rémi Cura <remi.cura at gmail.com>
>
>> Just to be sure could you validate please?
>>
>> The way I intend to find a source topogeom is related to target topogeom
>> is like this (in sql pseudo code):
>>
>> element_id is supposed to be the element_id found in the relation table
>> regarding *source* topogeom :
>> Example : what are the (lineal) target topogeom related to the (puntal)
>> source topogeom :
>>
>> `SELECT abs_next_left_edge UNION SELECT abs_next_right_edge
>> WHERE element_id = start_node OR element_id = end_node`
>>
>>
>> with the following
>> target
>>
>> puntal : SELECT start_node UNION SELECT end_node
>> lineal :  SELECT abs_next_left_edge UNION SELECT abs_next_right_edge
>> areal : SELECT left_face UNION SELECT right_face
>>
>>
>> source:
>>
>> puntal : WHERE element_id = start_node OR element_id = end_node
>> lineal : WHERE element_id = abs_next_left_edge OR element_id =
>> abs_next_right_edge
>> areal : WHERE element_id = left_face OR element_id = right_face
>>
>>
>>
>> This may not be the optimal (we could use shortcut with edge_id), but it
>> is symmetric in every way.
>>
>> Cheers,
>> Rémi-C
>>
>>
>> 2013/10/23 Rémi Cura <remi.cura at gmail.com>
>>
>>> Function getRelated is working for getting lineal related to a given
>>> puntal topogeom,
>>> now I'm trying to generalize so to be able to get any topogeom related
>>> to any topogeom, whatever the feature_type.
>>>
>>> Cheers,
>>>
>>> Rémi
>>>
>>>
>>> 2013/10/22 Rémi Cura <remi.cura at gmail.com>
>>>
>>>> OK,
>>>>
>>>> for my private function I don't expect several topogeom columns in one
>>>> table.
>>>> I can correct the getlayerid function but I don't think other people
>>>> than me need it.
>>>>
>>>> For the GetRelated, I have a working query and I'm now trying to make
>>>> it a plpgsql function
>>>>
>>>> Cheers,
>>>> Rémi-C
>>>>
>>>>
>>>> 2013/10/22 Sandro Santilli <strk at keybit.net>
>>>>
>>>>> On Tue, Oct 22, 2013 at 05:17:55PM +0200, Rémi Cura wrote:
>>>>> > I'm sorry for being so disorganized,
>>>>> > I lack experience with postgis_topology.
>>>>> >
>>>>> > It is only the 3d function I write for it.
>>>>> >
>>>>> > I was supposing you would need the layer_id in case there are
>>>>> multiple
>>>>> > topogeom columns in one table.
>>>>> >
>>>>> > Still I don't see a use case for having multiple topogeom columns in
>>>>> the
>>>>> > same table, even if I do use multiple geom columns for one table
>>>>> sometimes.
>>>>> >
>>>>> > I totally agree with your others conclusions and proposed signature
>>>>> > SET OF topogeometry GetRelatedLineal(
>>>>> >            a_source_lineal_topogeom TOPOGEOMETRY,
>>>>> >            a_target_puntal_topogeom_layer_id INT )
>>>>>
>>>>> Note that there's no problem with having multiple TopoGeometry columns
>>>>> in
>>>>> the same table, as long as you reference a each column (layer) by the
>>>>> "topology_id"/"layer_id" pair (topology.layer primary key).
>>>>>
>>>>> > I don't like to put layer_id directly as input in function because
>>>>> it is
>>>>> > not a number user fixed.
>>>>>
>>>>> In that case you can specify (schema_name, table_name, feature_column),
>>>>> which _also_ identifies rows in topology.layer.
>>>>>
>>>>> > I think I can live with that as I wrote a function to get layer id
>>>>> from the
>>>>> > topogeom name :
>>>>> > public.rc_getlayerid(layer_name text, layer_schema text DEFAULT
>>>>> ''::text)
>>>>>
>>>>> Missing a column name here ?
>>>>>
>>>>> --strk;
>>>>> _______________________________________________
>>>>> postgis-devel mailing list
>>>>> postgis-devel at lists.osgeo.org
>>>>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-devel
>>>>>
>>>>
>>>>
>>>
>>
>
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