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I am using the Cost Distance tool in ArcMap 10.2 to find the how far it is to walk to the closest area of green space along the road network in a town.

I have a input raster of the location of the green spaces and a cost raster of the road network. For the cost raster a road suitable for pedestrians is given a cost of 1 and an unsuitable road is given a cost of 10.

The tool produces a sensible output as the costs increase with greater distance from green spaces, but I do not understand what the cost values correspond to. I assumed that as the cell size was 10 m an area 400 m from a green space would have a cumulative cost of 40 (400/10 = 40) this is not the case.

Is there a way of converting the cumulative cost result into a real world measure (i.e. distance) or is there another tool which would perform this analysis.

EDIT

The picture shows the result of the Cost Distance tool, the green space is in green the roads in red with darker desk showing a higher cost. Cost values next to green space are 70 increasing to 5070.45 at a distance of about 500 m.

enter image description here

  • some data examples and pictures of the results might be valuable. Also consider reading about the Path distance, briefly it enables to accomodate the actual surface distance, in comparison to the cost distance that only refer to the cost allocated to each cell, but not to its size – dof1985 Mar 9 '15 at 16:26
  • It's difficult to determine what this output means without seeing the input. Perhaps you could zoom into a small portion of this image to show the detail and also provide a parallel image of the impedance grid? – whuber Mar 9 '15 at 22:19
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Your assumption concerning the output values is wrong. The cost-values are multiplied with the distance when using the cost-distance function. Hence 500m equal a cost-distance value of 5,000. I can only guess but I think the 70 may equal the cost-distance value from the center of the green pixel to the next cost-pixel. I see that there are high cost-distance-values next to green pixels. Try to add the green pixels to your cost raster with the same value like your roads. This might help you to avoid this problem.

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