Least Cost Path - for dummies

[JaredReid1]

I have never used Least Cost Path before and the online help is WAY over my head.

Can someone please break it down for me how to find the Least Cost Path between 2 points?


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The data I have to weigh this path is as follows:

One NED from USGS with elevation in meters.
2 points (My start and end points)
4 High Consquence areas polygons (ecological sensitive, drinking water, other populated, and highly populated)

thanks,
Jared

[JaredReid1]

That makes perfect sense.  Thanks!

[JaredReid1]

1 bonus question for you guys.


I have a corridor or route that I want to show preferential treatment too.  Is there anyway I can reclassify a raster and give it a negative value to subtract away from the cost of other rasters that may be on top of it?

[Robert_LeClair]

Okay, I'm assuming this is your workflow - please correct me if I'm wrong.  You have x number of rasters to create your cost surface.

1. You used the RECLASSIFY GP tool to reclassify your rasters to the same "scale."


2. Once all your input rasters have been reclassified to the same scale, you used the WEIGHTED OVERLAY GP tool to create your cost surface.


3. Now you want the cost surface to have "good" cells dedicated to the preferred alternative.

So what I would try is the EXTRACT BY MASK GP tool with the original cost raster as the input, the route as the Input Raster or Feature Mask Data and create a new raster (RASTER1) that is for the route.

Then I would use the CON GP tool that uses an expression where VALUE IS NULL - would get a zero and non-NULLs would get a 1 or a 4 depending on what is considered "good" by you and create a new raster (RASTER2).

The last step is to use the CON GP tool again where:

Input Conditional Raster:  RASTER2
Expression Optional:  VALUE = 1 (or 4 - depends on what's good)
Input True Raster or Constant Value:  1 (or 4 - depends what's good)
Input False Raster or Constant Value (optional):  Original Cost Surface Raster
Output Raster:  RASTER3

So in SUM, what this "should" do is extract those raster cells that "overlap" with the preferred corridor.  Then you set a condition where it's preferred cell value or NULL.  Then you set a condition where if it's preferred cell value, the raster cell gets a 1 (or 4) and the other cells get the original cost cell value.  "Should" work...good luck!