[R-sig-Geo] Shortest path around obstacles (OT)

[Rick Reeves]

Hi Don:

The GRASS GIS Module v.net.path will compute shortest path distances 
between points
associated with a vector line dataset. The short story here is that 
GRASS is a separate
open-source software package that integrates very closely with R (e.g, 
spatial data move
transparently between the two systems)

You might check out the GIS links on the attached page to get a 
bird's-eye view of GRASS:

http://nceas.ucsb.edu/scicomp/SoftwareLinks.html

You would have to be creative in your use of coordinate systems, but you 
could solve this
problem using GRASS GIS.

Regards,
Rick Reeves
Don MacQueen wrote:
> This question is basically off topic, since it isn't truly an R 
> question, though it is certainly related to r-sig-geo. I ask here in 
> the hopes that someone can suggest a direction for me to look.
>
> I have a what is essentially a floor plan of a building (lines 
> representing walls, breaks in the lines representing doors, and so 
> on). I would like to have an algorithm that can calculate the 
> shortest distance between any two points (actually, large numbers of 
> pairs of points) that does not intersect any line (pass through any 
> wall).
>
> My real dream is to use these distances instead of Euclidean 
> distances as input to a gaussian random fields algorithm such as 
> those in the RandomFields package.
>
> I've done some web-searching for libraries of geometric algorithms 
> that might include this task, and have come across references to 
> Dystra's algorithm, and some mention of line of sight calculations, 
> as well as some algorithms for robotics (how the robot finds a path 
> from here to there, passing around obstacles represented as 
> polygons). So I have some leads.
>
> None the less, I'd really appreciate any suggestions from the folks 
> here on R-sig-geo.
>
> Thanks
> -Don
>   
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