[GRASS5] Re: (grass) v.reclass does nothing...

[Eric G. Miller]

On Thu, 20 Dec 2001 12:17:43 +0100, Markus Neteler <neteler at itc.it> wrote:

> > You can try -d option with v.reclass and get fewer
> > colors in the result map, but not two. This is what I
> > think strange (bug?).
> 
> Yes, this is *really* a bug. "-d" also damages the topology
> in the current implementation as open polygons occur.

Can you provide an example?  As far as I can tell, the
resulting topology from your "fields" reclass example
looks just fine.  I did not see any unclosed areas, or stray
line work...  Note, none of the "open" areas in the reclass
that are shown as polygons in the original 'fields' are
labelled.  Therefore, they can't be reclassed... 

> 
> > To get only two polygons in the result d.area, perhaps
> > you'd better use v.extract with -d. 

It'd be impossible to get two polygons from the example
in the test.  Compare with the original data.  There
are double lines bordering "adjacent" parcels in some
cases.  Presumably, these are "rights of way" for roads...
Indeed they are...

> Yes - my intention was to test v.reclass.

I think it is working properly.  That there are problems
in the v.support/v.build realm is undisputed (does not always
properly intersect lines and form new nodes, for instance).

-- 
Eric G. Miller <egm2 at jps.net>