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Does anyone know of a program that will allow kerneling that takes a boundary into account in its calculation rather than simply masking areas that are impossible?

So far I have found: GME add on for ArcGIS 10 (Hawthorne Beyer) - I get an error every time I specify a boundary shapefile. I've tried lots of different shapefile types and boundary complexities etc. It works fine when I don't specify a boundary.

AdehabitatHR package in R (Calange 2011) - this works well but the boundary you specify has to be very simple - line segments 3x kernel bandwidth in length, and not too tortuous. For my data this is a big oversimplification.

So I'm wondering if any other software can do it, GRASS or QGIS for example?

PolyGeo
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KimS
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5 Answers5

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At the core of kernel density estimation is the notion of distance. The best solution I know of is to use a better distance metric that accounts for boundaries, and varying costs of travel. It's best to choose a distance metric that fits the problem you're trying to solve. Overland terrain friction is great for hiking, but not for aerosol dispersion. Wind currents are essential for sailboat tracking, but irrelevant for driving directions.
Now that the notion of appropriate distance metrics is hopefully sufficiently motivated, I can recommend cost surfaces as a good general purpose distance metric. They are available in everything from ArcGIS, to R, to JavaScript and are fairly straightforward to construct. In qGIS for example, you can construct a raster friction surface and use that to calculate routes. Customize the friction surface to account for your boundaries, and you'll see the mass from the kernels around your points neatly spreading out around the obstacles.

JasonRDalton
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ArcGIS Pro just released an update that includes optional barriers parameter in Kernel Density tool. I think this is exactly what you are looking for. You can see more information on this here https://www.esri.com/arcgis-blog/products/spatial-analyst/analytics/whats-new-for-spatial-analyst-in-arcgis-pro-2-6/

This is only included in ArcGIS Pro, so if you are still using ArcMap, I suggest switching to Pro.

antonio
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I suggest you try spatstat package for R. There you may set an owin object to determine borders of the study area. Also there is a great tutorial for this package.

SS_Rebelious
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I'm actually helping with AniMove plugin for QGIS, that aims to get rid on R dependence for kernel density estimation. Take a look here.

EDIT: The plugin is actually available as experimental in the official QGIS plugin repository

And don't hesitate to ask on the list, if you have any suggestion

Jorge Arévalo
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I have successfully done this using Geostatistical Analyst which is an extension of ESRI ArcGIS. You can load line features dataset as barriers and the results are pretty decent. I do test runs while changing the parameters of the functions to get a clear idea of how to calibrate the tool. To validate the results, what I recommend is if you have a big enough dataset is remove a sample of points, generate the density surface without those points, then compare the difference between the values of the removed points with the values of the surface at the location of the removed points.

Petya
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