I am looking for a way to calculate a distance matrix between points, but not 'as the crow flies'. I want the distance to be calculated around a polygon layer.

Example 1: I have several fishing lodge points and I want to know the distance between them that a boat would drive. Boats cannot drive over land.

Example 2: I have fish survey points and I am interested in larval dispersion between protected areas. Fish larvae cannot go over land.

What is this analysis called? How do I do it?

  • would a line layer, like e.g. "waterways" be ok instead of your polygon layer? – MrXsquared Nov 21 '18 at 22:21
  • Sure, converting the polygons to lines is fine... – CEdwards Nov 22 '18 at 17:23
  • you may want to take a look at "QNEAT3" plugin for qgis 3.x. It can calculate network travel costs matrixes (e.g. meters) based on individual input line layers (e.g. waterways). The output might be confusing first because it plots lines "as the crow flies" but you get the network distances from n:n points within one layer as attributetable (or csv). – MrXsquared Nov 24 '18 at 18:56

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