[Qgis-user] Isolate one polygon from a layer

[Alister Hood]

Hi Chuck,
Sorry - I thought I sent this earlier.

> Date: Tue, 2 Aug 2011 12:47:50 -0700
> From: Chuck Young <wylie1066 at gmail.com>
> Subject: [Qgis-user] Isolate one polygon from a layer
> To: Qgis-user at lists.osgeo.org
> Message-ID:
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> I am trying to get an individual image of a polygon from a layer where
there
> are numerous polygons that are adjacent to each other and share common
> boundaries.  What I need to do is be able to hide the boundaries of
the
> surrounding polygons while getting a view of the selected polygon for
> display.
> 
> All data is stored in a Spatialite database.
> 
> Thanks in advance!!
> 
> Chuck

If you only need to hide the other features in the same layer, you can
do this with most types of layer by right-clicking on the layer in the
layer control, and choosing query (it is available in the layer menu,
too).  The polygon will need to have attribute data (in the simplest
case an ID or name column) which enables you to distinguish it from the
rest of the layers with a query.  Alternatively, in some situations it
might be convenient to put a polygon layer under everything else, use
fill style = no brush and border style = no pen, and just click
somewhere to select and display the polygon of interest.

If you also want to hide features outside that polygon which are in
other layers, then it is not possible.  There is a feature request, but
I doubt anyone currently intends to work on implementing it - see
http://hub.qgis.org/issues/3253.  If you need to do it in the meantime
you would need to either do what I described there, or use
"Vector->geoprocessing tools->clip" on all your layers.


Regards,
Alister