I know is easy to select uniques points, or polygons features from two datasources (using centroids and overlap, or buffer) , but it not so easy do the same with linestrings, many times it is even a nightmare.

So, how can you select uniques linestring from two datasources when there is very similar linestring features, some solaped, very near, o similar but not equals like this, or even more difficult, and if, in addition, you also want to select the unique segments of those linestrings ?

EXAMPLE two datasources with similar linestrings


I would like to share with you this technique that allows you to select those unique linestring elements from two different datasources.

What this technique do is:

  • Split lines that crosses with another line (only do it over one datasource, the other datasource keep untouched)
  • Create Black/White Mask from the untouched datasource.
  • Select lines or portions of lines from second datasource whose length is at least within a percentage (user selection) in the appropriate area of the mask from first datasource.

The full technique, step by step with example images, is described here: http://gisutilities.blogspot.com.es/2017/03/selecting-uniques-linestrings-features.html

This technique uses terminal commands line, QGIS, OpenJump and some script in python.

With this technique, you can get this (uniques linestring are green):

Example, uniques lines, green, and original lines, red

  • Please share more of your technique within your answer. – PolyGeo Mar 8 '17 at 10:02

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