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How do I count longest distance between two lines as shown at the picture in every bump using QGIS?

enter image description here

  • which software are you using? – JGH May 10 '18 at 16:16
  • I am using QGIS but i have acces to ArcGIS. – SKNG_geoinfo May 10 '18 at 16:51
  • Here is a workflow, create Polygons from all lines (Feature to Polygon), Create Centroids (Feature to Point), run Near to Find the distance from Centroid Point to Line Edge, Double the near Distance. – klewis May 10 '18 at 17:44
  • What have you tried with QGIS? If you wish to also ask about ArcGIS Desktop then please do so in a separate question with details about what you have tried and where you are stuck. – PolyGeo May 10 '18 at 20:16
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    If you exclude the "at every bump" criteria, what you're looking for is the "Hausdorff distance". A possible workflow would be to split the lines by each other, then for each pair of split segments calculate the Hausdorff distance. – ndawson May 11 '18 at 9:29
3

I see interesting suggestions I would love to try. Below is what I have tried so far.

A sample data rivers; I tried to mimic two rivers (type = straight and type = meander).

enter image description here

Then,

(1) Create a new layer of points along the meander river at 1 meter interval (or any interval to fit your required accuracy). I used v.to.point which returned a new point layer (layer name: Points along lines).

(2) Open the attribute table of Points along lines layer. Create a new field dist with an expression:

distance(
  closest_point(geometry(get_feature('rivers', 'type', 'straight')), $geometry), 
  $geometry
  )

The above expression add a new field which shows distance from each point to the straight river.

(3) Click on a point which you think the farthermost, observe corresponding distance (dist) value highlighted on the attribute table. (I missed the right one but it is easy to find the distance I want = 3.90036 meters.)

enter image description here

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