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

[Martin Renner]

Hi Gregory,

An ingenious idea! I guess it would work but I'd be a little bit concerned about the alignment of the predicted surface. For now, I'll try Facu's method and see how that goes.

Best,
Martin


On 29 Jan 2010, at 08:11 , Greg Snow wrote:

> Another approach that might be simpler (or it may oversimplify and not give good results) is to compute the distances between your points as the fish swim, then use multi dimensional scaling (cmdscale function or others) to get a set of points that represent those distances and do the rest of your analysis on the transformed points.
> 
> 
> -- 
> Gregory (Greg) L. Snow Ph.D.
> Statistical Data Center
> Intermountain Healthcare
> greg.snow at imail.org
> 801.408.8111
> 
> 
>> -----Original Message-----
>> From: r-sig-geo-bounces at stat.math.ethz.ch [mailto:r-sig-geo-
>> bounces at stat.math.ethz.ch] On Behalf Of Martin Renner
>> Sent: Wednesday, January 27, 2010 1:07 AM
>> To: r-sig-geo at stat.math.ethz.ch
>> Subject: [R-sig-Geo] kriging as fish swim, not as crows fly
>> 
>> 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
>> 
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