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I'm trying to create a slope raster layer using QGIS 2.0 on Windows XP.

I started with a points layer with the Z elevation attribute.

points

I then used the interpolation plugin to create a DEM.

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But, when I used the Raster Terrain Analysis plugin, it gave me a strange output. What can I be doing wrong?

enter image description here

  • What settings did you is? What projection is the data in? I have had issues in the past with data in a geographic projection – Ryan Garnett May 24 '14 at 2:46
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    You need to use a modified interpolation method since your z points are not equally distributed but along the contour lines. For inspiration, see grasswiki.osgeo.org/wiki/Contour_lines_to_DEM – markusN May 24 '14 at 8:34
  • projection: RGPF UTM Zone 6S – user25976 May 25 '14 at 22:55
  • would doing IDW interpolation through raster --> interpolation be a "modified interpolation" method? I've been playing around with GRASS tools in processing toolbox: s.surf.bspline and v.surf.IDW (but get error signals saying the raster cannot be loaded). using the GRASS toolbox, I end up with very large pixels. – user25976 May 27 '14 at 19:04

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