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What is the best method calculating travel distance between destination and point layer in QGIS when using OSGB 1936 / British National Grid coordinate reference system?

  • As far as I am aware distance calculations in QGIS all run of the Ellipsoid that is set in the project properties. The default and best for British National Grid is considered to be Airy 1830. – AWGIS May 10 at 9:17
  • thank you! In your experience what would be the best tool / method to calculate distance between a layer of points and destination? – Curious Girl May 10 at 9:19
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    In QGIS I would always use the Distance Matrix - depending on your desired output you can adjust the matrix type in the tool settings to get the desired result. – AWGIS May 10 at 9:22
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    Just be aware the distance matrix works best with points to points - if you are running it to other vector types then I believe it assumes the centroid as the node. – AWGIS May 10 at 9:26
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    They all give the exact same accuracy, the only thing they change is the output matrix. Yes it should be the same so long as you are measuring in the same units (e.g. meters, miles or km...). QGIS will use the CRS and reference ellipsoid for all it's measurements with native tools. 3rd party plugins may not. – AWGIS May 10 at 9:38
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The question of "what's the best method" is entirely subjective and specific to your situation. The best way to answer this question, in my opinion, is for you to research the different methods and try out the one(s) that seem to best fit your needs. Here's some information to help you get started.

As was discussed in the comments above, calculating straight-line distance ("as the crow flies") is a relatively simple task, and there are many ways to do this in QGIS (eg Distance Matrix).

On the other hand, calculating travel distance is more complicated. This is also called

  • "routing"
  • "network analysis"
  • "shortest path"
  • "path finding"

With these search terms you will find many sources that explain the different methods available in QGIS. For example:

  • ORS Tools plugin

    ORS Tools provides access to most of the functions of openrouteservice.org, based on OpenStreetMap. The tool set includes routing, isochrones and matrix calculations, either interactive in the map canvas or from point files within the processing framework. Extensive attributes are set for output files, incl. duration, length and start/end locations.

  • Online Routing Mapper plugin

    Generate routes by using online services (Google Directions, Here, MapBox, YourNavigation, OSRM etc.)

  • GRASS tool v.net.distance. This tool requires a road network layer. You can obtain roads from Open Street Map, the British Ordnance Survey or from other sources (see Open Data Stackexchange).

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