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I am using QGIS 2.2 Valmiera to try to find the average slope of a water course. I've drawn in the water course as a polyline over a large number of contour lines (the water course is long with a very large catchment area). What I've tried to do so far is create a tin file. I've used the Raster > interpolation function using the heights attribute of the contour line shapefile to make the tin and each time I try it gives me a mini-dump error. I've tried to simplify the geometry (from 392515 to 66801 vertices) but I still just get the mini-dump error.

Is there another way to get the slope of this polyline without having to make a tin file or am I doing something wrong in trying to make the tin?

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    There is a Computing the slope of the roads with QGIS tutorial which might be applied at your case. – lrssvt Dec 2 '14 at 14:22
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    The problem with the tutorial is that they use existing raster data. I am attempting to make a raster/tin file. – Andrew Earl Dec 3 '14 at 9:54
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    Have you tried both the interpolation plugin and the module under Raster -> Analysis -> Create grid? And what does your parameters look like in when you run the interpolation? – hexamon Dec 3 '14 at 15:04
  • No luck, I am using ArcGIS now on another computer and that created a tin file just fine. – Andrew Earl Dec 5 '14 at 10:34

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