[R-sig-Geo] shortest realistic distance for fish travel

[Michael Sumner]

A vaguely similar approach is provided by the (hard to use) code in the 
tripEstimation package.

This package is primarily for determining realistic track locations from 
raw archival light data or satellite locations with estimates included for 
the "intermediate path" between data collection times, but the methods used 
to apply auxiliary data such as SST or bathymetry, and simple speed models 
could be applied to your case.

I'd be happy to try an example to see if the existing code can be applied, 
although it might be a bit heavy handed.

Is there a freely available coastline data set that you would be confident 
using in your case? Is the GSHHS sufficient? Do you have other data that 
can be used to limit the likely/possible path?

Some more context for the package via an (out of date) light example can be 
found here:
http://staff.acecrc.org.au/~mdsumner/Rutas/tripEstimation-demo.pdf

Cheers, Mike.





--On Thursday, 18 December 2008 2:38 PM -0500 Jon Loehrke 
<jloehrke at umassd.edu> wrote:

> Hi,
>
> 	I am trying to find an algorithm or thoughts on approach for how to
> compute the shortest realistic distance between two points.  I define
> shortest realistic distance as the shortest distance between two points
> that a fish (which is what I study) could move through.  Hence the path
> must wrap around land, islands, archipelagos, etc.
>
> Point 1
>
> 41.15  	N
> 71.26 	W
>
> Point 2
>
> 42.17  	N
> 70.37 	W
>
> 	I'm sure this issue has come up with the geo-statistical community, but
> simply need a starting direction.
>
> Thank much and happy holidays.
>
> Jon Loehrke
> Graduate Research Assistant
> Department of Fisheries Oceanography
> School for Marine Science and Technology
> University of Massachusetts
> 200 Mill Road, Suite 325
> Fairhaven, MA 02719
> jloehrke at umassd.edu
> T 508-910-6393
> F 508-910-6396
>
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