How can I estimate kernel density, taking barriers (i.e. a priori zero-probability regions) into account?
At the moment, regions where the population cannot occur are clipped out for display. However, I imagine this is biasing the results, since observations near the zero-probability regions don't have as much impact as they might.
I have several thousand observations, so a tool or programmatic solution is a necessity. Bonus points for an implementation in ArcGIS or R.