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I have 5 groups of 4 lines, all the lines in all the data sets are centred around the same point. I need to algorithmically combine these lines into one line that is only the furthest from the point. They overlap in multiple locations.

image

Source: https://drive.google.com/file/d/19_dpKZUIaNpnfxk7KZF3AJJULXrURdum/view?usp=sharing

These lines came from points which came from a CSV file, they were combined using the 'Pointstopath' function in QGIS.

I am very new to GIS in general but have a working knowledge of python. My first thought was to load the CSV files into python pandas and calculate the distance from each point and only keep the furthermost. However, this won't work as the files have different "resolutions".

Am I missing something obvious?

  • Please use the image tool within the SE framework. Images in third party sites are less likely to be followed, and much more likely to fail over time. – Vince Aug 21 at 2:13
  • Thanks Vince, Unfortunately I couldn't as Imgur isn't available though my work's firewall. – Noah Aug 21 at 4:49
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If I understand this correctly, you need an outer boundary of the combination of all geometries in the layer. For that you can try this:

  1. convert all lines to polygons (Lines to polygons algorithm)
  2. union all polygons (Union algorithm)
  3. dissolve unioned polygons (Dissolve algorithm)

These steps should produce polygon which represents the outer boundary (or cumulative area) of all geometries.

  • Thank you, Exactly the solution I was looking for! – Noah Aug 21 at 6:10
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    If you want to do that in pure Python, take a look at the Shapely library... – DavidP Aug 21 at 6:20

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