I am an Archaeologist. I am interested in settlement dispersal and land use strategies in late antiquity and early middle ages.

Therefore, I want to analyze a certain terrain by: - least cost polygons or - terrain accessibility by time from a certain point.

I am using QGIS 2.18.6 ASTER DEM 30m (tiff) .CSV data for my settlement points.

GRASS and SAGA don´t want to operate. I calculated the slope as friction for r walk/ r drain.

I am surely not an expert and there might be some basic calculations missing. Maybe you can help me along or have another strategy how to draw my polygons.


From the grass comands section you can use use either r.cost or r.walk to define your cost surface. Then you can use r.drain to calculate the least cost path, so I'm not sure why it's not working. Potentially try with r.cost, see if that works.

This tutorial may help: http://gracilis.carleton.ca/CUOSGwiki/index.php/Evaluating_Landscape_Permeability_in_Quantum

Alternatively, the library 'gdistance' in R is really easy to generate cost surfaces. See https://cran.r-project.org/web/packages/gdistance/vignettes/gdistance1.pdf for a guide how to do it (Example 1: Hiking around Maunga Whau)

  • thank you! I finally got it done by creating a lot of diffeent cumm_cost_surfaces and drains and walks and so on. it seems it worked with me only by typing in the coordinates for r.drain manually..... – Michelino Oct 9 '17 at 14:34
  • No problem. Hope I helped. – user3384265 Oct 9 '17 at 15:48

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