Legend of the Buffer — Beware of 3 Important Mistakes

My Initial Presentation

What is a buffer?

Typical data pipeline generated with QGIS model builder

Mistake no. 1: A buffer is not a circle

Our conception of a buffer
An actual buffer

Mistake no. 2: Excluding some geometries within the buffer distance

Exclusion of a point at maximal distance
The number of vertices may change between different buffer algorithms

Mistake no. 3: Travel cost is (almost) never equal to a bird-flight distance

Google Maps travel time from Kamouraska to Malbaie

Better Alternatives to a buffer exist

Solution for finding geometries within a distance

  1. Calculate the distance between your input geometry and the other geometries
  2. Select only those with a distance inferior to your desired distance

Solution for a better distance representation

Source: bogotobogo

When should we use a buffer?

  1. You want to display the region around a given geometry
  2. You want to perform some spatial operation that absolutely needs a buffer

When should you not use a buffer?

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Zachary Déziel

Zachary Déziel

Product Manager @ Anagraph. Geogeek and outdoor enthousiast. Twitter @zacdezgeo