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I have a DEM raster and would like to carry out a cost path analysis.

Among other factors such as slope, proximity rivers etc. I would also like to take elevation into consideration. According to the model I am trying to build (using ArcGIS 10.1), the cost of building at high altitude locations would be much more costly compared to low altitude places.

I was wondering how I could create such a cost surface?

enter image description here

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1 Answer 1

up vote 2 down vote accepted

Choose a range of values for costs (e.g. 1 = low costs, 10 = height costs).

Reclasify each input data to a cost raster.

e.g.:

reclassify elevation:

  • altitude > 1000 m --> cost 10
  • altitude 900 to 1000 m -> cost 9
  • altitude < 100 m --> cost 1

reclassify proximity to rivers:

  • distance < 10 m --> cost 1
  • distance 10 to 200 m -> cost 2
  • Distance > 2000 m --> cost 10

Combine all cost raster to a single cost raster. If a factor is more important than others you can use a different weight for each factor. Use Raster Calculator tool to calculate total costs. E.g. if elevation is more important than proximity to rivers you can use:

“cost_elevation” * 0.8 + “cost_rivers” * 0.2

In ArcGIS Help you find more information.

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Thanks for that I really appreciate it –  user19622 Jan 13 at 12:08
    
Hi, I tried doing what you suggested (I've edited my original question by posting an image of the output), but I was wondering, in regard to the reclassification, how I can get it to show what the actual colour represents (e.g. yellow= 0m, blue=100m green=200m etc.) rather than just 1,2,3,4... is this possible or have I missed a crucial step? Any suggestions would be very much appreciated! –  user19622 Jan 13 at 12:21
1  
The raster dataset you created (reclass_img5) has the reclassified values (1 to 10). The raster “does not know” that “1” means “0 m” and “2” means “100 m”. If you really want to show “0 m” “100 m” … in the TOC you have to change the label manually in the layer properties dialog (symbology tab). –  Jens Jan 13 at 12:59
    
thanks, so does that mean reclass_img5 is the elevation cost surface raster - I mean it 'looks' right? just want to be sure that 1,2,3,... is normal! –  user19622 Jan 13 at 13:58
    
If you've decided that the cost range is 1 to 10 then all cost raster must have values 1 to 10. Your screenshot shows the “normal” output. But I suggest that you use other colors. E.g. from 1 dark red to 10 light red. Then you will see that pixels near the river have low costs (dark red) and pixels with a large distance to river have height costs (light red). –  Jens Jan 13 at 14:46

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