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

[Nicholas Lewin-Koh]

Hi,
You are talking about network distances. One approach would be to 
label all your source areas as nodes, and then create a series of way
point
nodes. From this you can build a graph that connects all source
populations with each other
and then run the all shortest path algorithm to find the most likely
routes. 

another approach would be to define your landscape as a grid, where each
cell has a cost to pass through,and landmasses are set to infinity.
Again 
connect each cell with its neighbors, and find the shortest path between
any two points.

Hope this helps

Nicholas


--------------------------------
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.