Geography Reference
In-Depth Information
Figure 5.5: Digitized Streams
In QGIS the tolerance is set in map units, so you may find you need
to experiment to get it set right. If you specify too big of a tolerance,
QGIS may snap to the wrong vertex, especially if you are dealing with
a large number of vertices in close proximity. Set it too small, and it
won't find anything; it will pop up an annoying warning to that effect.
To set the snap tolerance, open the Project Properties dialog box, click
the General tab. Remember the tolerance is in map units. If you want
to make sure, use the Measure Line tool to examine the distance between
vertices to make an educated guess at a proper value. Since our data
is in meters, a value of 2.0 seems to work well. This of course depends
not only on the map units but also the scale at which you are digitizing.
Fortunately, you can tweak the tolerance to get something that works.
Once the tolerance is set, we can move the vertices to fix the dangles.
With the Move Vertex tool selected, place the cursor over the vertex to
be moved and drag it to the new location. When you release the mouse,
the vertex is moved, and the shape of the feature changes. You'll notice
 
 
 
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