I have about 10 points and I want to run Cost Surface Analysis. I’m trying to find what distance a person can walk in a given amount of time from a certain point (5-10 or 15 minutes). What procedure follow and what data I need. I have DΕM of the region. I use ArcGIS 10.3 and I read from online help the Creating a cost surface raster, but I'm not sure what I have to do.
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do you have spatial analyst ?– radouxjuMay 13, 2015 at 18:00
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Yes I do have Spatial analyst– VassilisMay 13, 2015 at 18:02
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If you have access to the ESRI virtual training campus there is a very easy to understand 3 hour course called Distance analysis in ArcGIS which teaches cost path tools and how to use them. If you have access and the time I would highly recommend this.– HornbyddMay 13, 2015 at 23:40
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Can you send me as a commend the title of hte course?– VassilisMay 15, 2015 at 13:24
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2 Answers
Here is a great video that helped me out for explaining Cost-Path: https://www.youtube.com/watch?v=d0Eywj4pIu8
As mentioned before, this requires a DEM to create a slope raster using Spatial Analyst Tools -> Surface -> Slope.
However, for what you are looking for (get a detailed perspective on hiking from point A to point B), you can implement Tobler's hiking function which will estimate the time it takes to traverse over slope assuming an initial unaffected walking pace of 5.037 km/hr. The speed/time to traverse over terrain changes based on the slope raster derived from elevation data (DEM).
http://www.mapaspects.org/node/3744
From the above link, go down to B. ANISOTROPIC TIME ESTIMATE USING PATH DISTANCE and download the appropriate Tobler table for your use (Tobler-away/towards) and input it into your environment variables as mentioned in the step-by-step guide. Eventually, you will end up with another raster that you can use to calculate contours based on your desired time intervals. You can use these to calculate accurate hiking time across the slope raster. This requires less raster calculation than the cost-path process mentioned above but it still requires the cost-back link raster that is explained in the video. Should give you what you want.
In your case, the best tool is probably the "Path Distance" Tool, which will take your DEM into account to adjust the speed. There is a long description on this page on the option to set the speed. Note that the relationship between speed and slope depends on your travel type. By bike, you go faster downhill than uphill, so this is more like a linear cost. By foot, you walk up and down at approximately the same speed, and you can climb bigger slopes than a bike, so you need to use a symmetric cost.
once you have your path distance raster, you can reclassify to identify the areas of interest. If you have a land cover layer, you can use it as a friction raster o modify the speed (e.g. slower in sand than on a road)
EDIT: 5 to 15 min is a short walk, so there will not be large effect of speed difference (except if you have obstacles or very steep slope). You could simply make buffers of 1.25, 0.83 and 0.415 km (respectively 15, 10 and 5 minutes for a fit walker: 5km/h)
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Hi and thank you for your answer. The scenario is that moving on foot and want to find how far you travelled over 5, 10 and 15 minutes. So you have to somehow calculate the distance in relation to the time and challenge.– VassilisMay 13, 2015 at 18:54
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depending on the walker, walking speed range from 3 to 5 km/h. so you can get the time by dividing the cell size by the speed. If there is a "challenge" that hinders normal speed, you can use a cost raster with longer time for more difficult walk. I don't understand the information that your are looking for (problem using the tools or problem finding typical speed values). So you would attract better answers by editing your question.– radouxjuMay 14, 2015 at 8:35