[GRASS-user] raster area problem

[Jason Jorgenson]

Hi all.  This is my first attempt at using the mailing list...

I have digitized a topo map's landuse classes into a vector layer, and then
converted the vector to a raster.  I want to see how much land would have
been required for settlements at point x,y with population of 'P' to sustain
themselves.  Example, for site 'Shuna'  with a population of 5000 I need 16
sq km (of landuse classes 1,2,5 (agricultural,olive,fruit)).
http://arkygeek.blogspot.com  for a crude drawing of what i mean...

 What I am trying to do is (ultimately) determine the radius of the circle
that will contain 'A' square meters of usable land.  These are the general
steps I have come up with...

1.  the landuse classification data
       - convert the vector layer of classified land to a raster.

2. this new raster will contain 2 values - 0=not usable and 1=usable
(??should i do this??) and then I can do this
     - ask for population size of settlement
     - ask for site to analyze which will give xy
     - ask for ratio of crop:fallow  (any other variables can be set here as
well)
     - computer determines amount of land required to sustain population
     - calculate the radius of a circle surrounding site that encompasses
the required amount of land

3. The logic for calculating the radius looks like this: (??????)

    for every locality do
       set solution found flag to false
            while solution not found
                 increment proposed radius
                 select all cells within proposed radius
                 test if solution is found

4. Once the radius is found, mask the results, convert the results to a
vector, and this should give me the solution. (???????)

Any suggestions???

Thanks for your time!



-- 
Jason Jorgenson
Post Grad Research Student
University of Liverpool

"If you don't get out of the box you've been raised in, you won't understand
how much bigger the world is." - Angelina Jolie
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