[Qgis-user] Can QGIS plot single line segments?

Tim Keitt tkeitt at gmail.com
Tue Jul 20 09:11:43 EDT 2010


Ah, good catch. I must have accidentally duplicated the node indices
when constructing the lines.

THK

On Tue, Jul 20, 2010 at 12:47 AM, Gavin Macaulay <gavin at macaulay.co.nz> wrote:
> Tim Keitt wrote:
>>
>> I have what I think is a perfectly good shape file. ogrinfo returns
>>
>> NFO: Open of `jagmesh.shp'
>>      using driver `ESRI Shapefile' successful.
>>
>> Layer name: jagmesh
>> Geometry: Line String
>> Feature Count: 19047
>> Extent: (-3547484.000000, -5785886.000000) - (4866967.000000,
>> 3747255.000000)
>> Layer SRS WKT:
>> PROJCS["Lambert_Azimuthal_Equal_Area",
>>    GEOGCS["unnamed ellipse",
>>        DATUM["unknown",
>>            SPHEROID["Unknown",6370997,0]],
>>        PRIMEM["Greenwich",0],
>>        UNIT["Degree",0.017453292519943295]],
>>    PROJECTION["Lambert_Azimuthal_Equal_Area"],
>>    PARAMETER["latitude_of_center",0],
>>    PARAMETER["longitude_of_center",-80],
>>    PARAMETER["false_easting",0],
>>    PARAMETER["false_northing",0],
>>    UNIT["Meter",1]]
>> is.edge.so: Real (11.0)
>> is.edge.ta: Real (11.0)
>>
>> I loaded it into postgis. The first 5 lines are:
>>
>>  gid |                                      astext
>>
>> -----+-----------------------------------------------------------------------------------
>>   1 | LINESTRING(-118068.9 -658036.18355628,-118068.9 -658036.18355628)
>>   2 | LINESTRING(-120565.103973043 -652437.1,-120565.103973043 -652437.1)
>>   3 | LINESTRING(-108926.6 -648353.4,-108926.6 -648353.4)
>>   4 | LINESTRING(3666461.07939581 -119248.798562935,3666461.07939581
>> -119248.798562935)
>>   5 | LINESTRING(3636409.07468477 -129061.988213268,3636409.07468477
>> -129061.988213268)
>> (5 rows)
>>
>> Neither the shapefile or the postgis table will display in QGIS. QGIS
>> clearly digests the data and looks like it wants to draw something,
>> but the plot is blank.
>>
>> THK
>>
>>
>
> Tim,
>
> The 5 linestrings that you gave as an example are all of zero length. Hence
> if all 19407 linestrings have that property, what qgis is displaying is
> appropriate.
>
> Regards
>
> Gavin
>
>
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-- 
Timothy H. Keitt
http://www.keittlab.org/


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