I am very new to GIS, so excuse my potentially poor terminology. I am trying to create a cost surface in qgis. I have an raster with elevation data. Based on that I created a slope with the DEM Terrain models tool. Then I use the r.walk.points algorithm to calculate Movement Directions and Cumulative Costs. However, the resulting rasters are exceeding the input rasters (see screenshots). All rasters are using the same CSR. What other information could be helpful to find the mistake? What am I doing wrong?


Exceeding Movement directions raster:


This problem occurred in QGIS 2.18. on Ubuntu 16.04. In QGIS 3.4.1 everything works as expected. Below I also provide a workaround for 2.18. However, I'll leave the question open for the case someone finds a real answer.


I found two possible workarounds:

  • Update to QGIS 3.4.1.
  • For QGIS 2.18: In the r.walk.points tool, use "GRASS GIS 7 region extent" to manually select an area that is smaller than the input slope raster.

However, I'll leave this question open in case someone finds a real answer.

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