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ArcGIS Path Distance: Tobler's Hiking Function

Question asked by lawlerba on Mar 25, 2016
Latest reply on Mar 25, 2016 by Dan_Patterson

Hi All,

 

I am definitely no expert in ArcMap and could really use some help.

I have been working on calculating the cost to travel from raw material toolstone sources in Interior, Alaska using Tobler's Hiking Function. I followed Kaitlin Yanchar's tutorial: ArcGIS Tutorial: Tobler’s Hiking Function (Anisotropic Distance) | Kaitlin Yanchar, MA, RPA in a version of ArcMap 10. I used a 100m resolution DEM, 32 bit floating point raster. I clipped the DEM to only include the analysis extent which is about a 46,000 square mile area, and then followed the steps of the tutorial. Slope is the only friction surface I used. The cost raster and resulting values of the cost raster appear to be anisotropic and correct in relation to one another, but I am having a problem similar to Mathew Schmidtlein. My values are not underestimated, they seem to be significantly overestimated, such that the time it would take to travel several hundred miles, when the cost is converted from minutes to years, would take several years. I followed the tutorial twice and came up with the same values. There is steep terrain in the area, but I looked at the slope values and there are none that are over 70 degrees, so I don't think ArcMap is getting hung up on terrain that may be impossible to traverse. Does anyone have any ideas why I may be getting such huge cost values? Is it possible that the values of the cost raster are not in minutes?

 

Thank you for your help,

Brooks

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