[R-sig-Geo] kriging as fish swim, not as crows fly

[Facundo Muñoz]

Hi Martin.

I have succeeded in doing something like that.
Please see http://dx.doi.org/10.1016/j.mcm.2009.05.021.

I used GRASS for the computation of the non-euclidean distances and 
modified the geoR library in order to be able to estimate de variograms 
and perform kriging prediction with those "customized" distances.

Both the GRASS script for computing distances and the modified geoR 
library are open source and available at 
http://www.geeitema.org/guenmap/index.jsp?opcion=resultados


I hope it helps.
	ƒacu.-


Martin Renner escribió:
> Hi All,
> 
> I want to kirg fish and seabird densities within an estuary which has several arms. Since neither organisms cross land, the appropriate distances would not be euclidian but over-water (as fish swim). There are several papers, describing this problem and how to deal with it (see below), but I have not found an easily accessible implementation. Is anybody aware of a solution in R?
> 
> Best,
> Martin
> 
> 
> 
> @article{Rathbun:1998aa,
> 	Author = {Rathbun, Stephen L.},
> 	Journal = {Environmetrics},
> 	Number = {2},
> 	Pages = {109--129},
> 	Title = {Spatial modelling in irregularly shaped regions: kriging estuaries},
> 	Volume = {9},
> 	Year = {1998}}
> 
> @article{Little:1997aa,
> 	Author = {Little, Laurie S. and Edwards, Don and Porter, Dwayne E.},
> 	Journal = {Journal of Experimental Marine Biology and Ecology},
> 	Number = {1},
> 	Pages = {1--11},
> 	Title = {Kriging in estuaries: as the crow flies, or as the fish swims?},
> 	Volume = {213},
> 	Year = {1997}}
> 
> 
> 
> 
> Martin Renner				
> US Geological Survey			
> Alaska Science Center