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

[Alex Mandel]

On 07/19/2010 08:04 PM, 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
> 

This might just be an artifact of Scale. Those coordinates look quite
far apart so if QGIS zooms to full extent at the default line width
you'd see nothing. Try either changing the line width or opening the
table selecting a record and zooming to the record.

Enjoy,
Alex