I'm new to least cost analysis. I have a DEM-layer of a region and I want to know what's the least cost path from a to b. Do I have to use the DEM layer to calculate that? I also have a hillshade layer and a slope layer of that region. I think the DEM-layer only has the heigth of the landscape, but doesn't slope affect the costs of a specific route as well? Do I have to combine these layers? I have QGIS 3.8 and 3.6

  • Without a road network this is kinda... boring. Also, what prior research on the topic have you done? Have you found a workflow, which you are trying to follow? If so, where are you stuck? If not, are you aware, that your question might be closed for being too broad?
    – Erik
    Aug 23, 2019 at 14:10

1 Answer 1


Terrain cost analysis typically uses slope, combined with whatever else you'd like to take into account (soil, weather-ground conditions, land cover, vehicle attributes, etc). If you're just wanting to look at the slope, then the basic idea is to categorize the slope values and assign them an associated cost value. For example:

  • Slope 0 - 5 could have a cost of 1
  • Slope 5 - 10 could be 2
  • Slope 10 - 20 could be 3
  • ...
  • 40+ could be 6

This resulting "cost raster" could then be used for things like finding a least cost path.


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