[postgis-users] Checking Road Network Topology

Rémi Cura remi.cura at gmail.com
Fri Jan 23 04:30:20 PST 2015


For my data I also had to use a tolerance, the 0 tolerance gives errors.
Cheers,
Rémi-C

2015-01-23 13:04 GMT+01:00 toni hernández <toni at sigte.udg.edu>:

> yeah! that's it.
> thanks.
>
>
> On 23/01/2015 11:34, Sandro Santilli wrote:
>
>> On Fri, Jan 23, 2015 at 10:46:43AM +0100, toni hernández wrote:
>>
>>> Sandro,
>>>
>>> At this point I am not sure. :-(
>>>
>>> I tried again using srid=4326 and a tolerance of 0.0001 which for my
>>> latitud (Girona, Spain) is about 1 meter.
>>> This time everything worked just fine.
>>>
>> Great!
>> So, to recap, tolerance=0 errored out while tolerance=0.0001 worked fine ?
>>
>> Note that when a tolerance=0 is given, the code would actually compute
>> the tolerance for each line geometry added looking at the smallest
>> representable shift from the biggest ordinate value in input.
>>
>> There are known robustness issues in the topology builder which you can
>> find on the tracker. You might have encountered one of these. The idea
>> to load in chunks serves the purpose to be able to fix such issues locally
>> when they happen, understanding your data better and tweaking tolerances
>> on a feature basis (if needed).
>>
>> --strk;
>>
>>    ()   Free GIS & Flash consultant/developer
>>    /\   http://strk.keybit.net/services.html
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