[postgis-users] topology overlapping of edges

[Mario Jurcevic]

It will help if Topology validation could be defined by rules, so that 
during import
of already topological data the user can disable it or enable it as needed.

For my import I will update the pointers of edges my own, could you 
Sandro point me to
specifications of  next_*_edge.

Thanks



--
http://www.soft-gis.com


On 09/28/2012 03:31 PM, Sandro Santilli wrote:
> On Fri, Sep 28, 2012 at 02:50:03PM +0200, Mario Jurcevic wrote:
>> On 09/27/2012 10:06 AM, Sandro Santilli wrote:
>>> You can always skip all tests and insert the edges straight away, if
>>> you know exactly what's expected as the structure. It will be faster.
>>> You can then check with ST_ValidateTopology what's missing
>>> (theoretically). That's what the TIGER loader does, for example, but
>>> the input is already topological, no need to check.
>> My input data are already topological ( only lines are given ) so
>> inserting straight  to table edge_data will work without noding and
>> checking for intersections
>>   but what about next_left, next_right, etc pointers?
> You'll need to set them up yourself, or you could rely on standard
> ISO population methods ST_AddIsoNode for each of your nodes,
> ST_AddEdgeModFace for each edge.
>
> The code will still run many tests to ensure there's no edge-edge or
> edge-node crossing, but noding would be skipped and those items
> will be appropriately set.
>
> I've been thinking for some time that we could expose some functions
> that perform less check (delegating all checks to ST_ValidateTopology)
> but so far the whole focus has been on correctness more than speed.
>
> --strk;
>
>   http://www.cartodb.com - Map, analyze and build applications with your data
>
>                                         ~~ http://strk.keybit.net
>
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