[postgis-users] Intersection errors out with null directed edge

[Martin Davis]

Currently your only option is to run isValid on your geometry table.  It 
will identify any geometries which are not valid. 

To see the actual nature and location of the errors you will have to 
export them to another tool (such as JUMP or JTS TestBuilder) to see the 
actual nature & location of the errors (Providing similar functionality 
is on the ToDo list for PostGIS)

Martin


Chris Hermansen wrote:
> Hello again;
>
> So with GEOS 3.0.0RC4 the problem now becomes:
>
> TopologyException: EdgeRing::computePoints: found null Directed Edge
>
> I believe there is in fact something wrong with the data.  However the
> TopologyException does not identify the source of the problem.
>
> In looking through the mailing list archives, I see questions around
> this issue have come up in the past (eg September 2006).  I don't see
> anyone suggesting ideas on how to find the offending data elements.
>
> Also, trolling through google doesn't seem to turn up anything.
>
> Does anyone have any ideas on how to explore the data to look for
> problems such as this.
>
> Thanks in advance!
>
> On Thu, 2007-13-09 at 11:31 +0200, Andreas Laggner wrote:
>   
>> Hi Chris,
>>
>> as i had this errors i installed postgis with GEOS 3.0, and such an 
>> errors never occurs again! I am not sure, but postgis 1.3.1 can be built 
>> with GEOS 2.2 too......just run the query select postgis_full_version(); 
>> and check your version of GEOS.
>>
>> cheers      Andreas
>>
>>
>> Chris Hermansen schrieb:
>>     
>>> Hi folks;
>>>
>>> I had this problem today:
>>>
>>> AssertionFailedException: EdgeRing::computePoints: found null Directed
>>> Edge
>>>
>>> I see in the archives that there are others who have suffered this, back
>>> in 2006 and then in 2005, but there don't seem to be any offerings of
>>> techniques to either repair the code or the data - and based on the
>>> error above, I'm not sure which is ultimately at fault.
>>>
>>> Does anyone have some more up-to-date thought on this?
>>>
>>> I'm running postgis-1.3.1 on Ubuntu with the packaged postgresql-8.2
>>> installed.
>>>
>>> Thanks in advance!
>>>   
>>>       
>>     

-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022