[Qgis-user] Extra lines to origin

[Adam Dershowitz]

> On Mar 15, 2016, at 8:14 PM, Alex Mandel <tech_dev at wildintellect.com> wrote:
> 
> On 03/15/2016 11:02 AM, Adam Dershowitz wrote:
>> I have a DWG fie that was provided to me.  If I use any of a few viewers it appears to be correct.  I then used TeighaFileConverter to convert it to a DXF file, and again it appears to be correct.  But, when I import it into qgis, the LineStrings generally have the correct shape, but also have extra lines that go over to the origin.
>> My DWG shape file is somewhat away from the origin.  So, that means that  there a whole bunch of extra lines connecting my object over to the origin when viewed in QGIS.
>> I tried a few different DXF version of the export with no change.  And, a few other viewers that don’t seem to have that problem.
>> Does anyone have any suggestions for why that might be happening?  Or how I can prevent it?  Or, as a work around is there any way to just filter out all the points that are near the origin?  
>> This first occurred in QGIS 2.12, but I just upgraded to 2.14 and confirmed the same problem.  I am using Mac OS 10.11.3.
>> 
>> Thanks,
>> 
>> 
>> --Adam
>> 
> 
> It sounds a little like invalid geometries, or geometries that cross the
> edges to wrap around to the other side (a common issue with data at the
> dateline for example).
> 
> Try running the geometry checking tools.
> 
> Thanks,
> Alex
> 

The geometry checking tool does report hundreds of errors.  Many of these are "line 0 contains 7 duplicate node(s) at 8”  So, what can I do about it?  Any suggestions for why this happens and how to fix it?
The data is not near a dateline, but is just a region in the middle of a state plane zone, except for all the lines that go over to 0,0.  And, as I said, the DWG, and DFX both look OK in other viewers.