[GRASS-user] Fuzzy logic in GRASS

Rich Shepard rshepard at appl-ecosys.com
Wed Mar 3 09:13:22 EST 2010

On Wed, 3 Mar 2010, Jaros?aw Jasiewicz wrote:

> There are at least however on problem:
> r.fuzzy for GRASS exist and not exist (by Francois Delclaux). I tried to 
> contact with author but it failed and  module is not available from add-on 
> web page. For now I leave name r.fuzzy, but if it could be the problem I can 
> change name or remove both module.


   I've been in contact with Francois after downloading the most recent
version (2000) of the code. At my request he sent me a thesis written by his
student who did most of the work. It's all in French, and my ability to
read, write, and speak that language has deteriorated over the decades to
the point that it's virtually useless. I'll be happy to share what I have.

> - for r.fuzzy shape parameter use nonstandard solution which is not applied 
> in any software known for me. What you think about it? Or shall I change it 
> into standard dilatation/concentration parameter (power/sqrt)

   Hedges come in a range of degrees of strength. 'Slightly' is a different
hedge from 'very', for example.

> - i plan to add custom fuzzy set definition but it require manual typing of 
> sets of points or some more complex membership function definition which may 
> be difficult without visual assistance, so I'd like to know if it would be 
> really useful

   In my opinion, what is needed first is a comprehensive description of what
such a set of modules is intended to do. That is, in what situations should
it be used and what insights should come from the results. This information
then guides how it should work with raster and vector (lines, areas, points)

   I see two immediate applications. First, for areas traditionally delimited
by crisp boundaries (e.g., soils, geology, wetlands) we should have a
mechanism to define fuzzy boundaries. Second, we should have a mechanism to
query maps with terms such as 'near,' 'far,' 'large,' and 'steep.'


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