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How can I find the least-cost-paths between a network of several points using QGIS or other easily available tools? That is, the easiest way to get from each point to every other point in the network, as opposed to just between one start and one end point.

The start and end points are polygons scattered unevenly across the map, and the intervening landscape is a patchwork of fields etc. for which the permeability score of each landscape feature is known - the least-cost-paths will need to choose any possible route through the fields, not follow roads or similar.

(I am using QGIS-2.14.1-Essen with GRASS).

closed as too broad by Vince, PolyGeo May 13 '16 at 21:15

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    Please ask only one question per question, for only one software platform (this is effectively four questions) – Vince May 13 '16 at 18:36
  • I reckoned that I'd have to explain most of the other questions for the individual questions to make sense! – EVWK May 13 '16 at 19:30
  • Nothing overly complicated. Set any point as destination, compute back link raster for your cost surface, compute cost paths from the rest. Repeat 60 times to answer 2nd q, storing Eg 5 nearest distances or 30 times – FelixIP May 13 '16 at 21:09
  • Oops. 60 times to answer both – FelixIP May 13 '16 at 21:18
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    This question appears to be a duplicate of gis.stackexchange.com/q/193046/115 but both could do with heavy revising to try and make what they are asking clearer. – PolyGeo May 13 '16 at 22:00
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This to me sounds similar to a water flow analysis on a DEM. That basically calculates the lowest surrounding point and draws the path of water. Maybe this type of approach would be a helpful place to start?

https://docs.qgis.org/2.2/en/docs/training_manual/processing/hydro.html

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