[GRASS-user] Defining Minimum Mapping Units

[Markus Neteler]

On Wed, Jan 20, 2010 at 7:03 PM, Luis Lisboa <luislisboa1975 at gmail.com> wrote:
> Greetings all
> I've been reading a Remote Sensing classic "Remote Sensing and Image
> intepretation" by Lillesand and Kiefer. :)
> By Those guys Minimum Mapping Units are the smallest size areal entity to be
> mapped as a discrete area.
> They also state that: The size of a minimum area that can be mapped as any
> particular land use/land cover class depends on the scale and resolution of
> the satellite images."
> Ok, now my "situation" :). I need to produce a few land cover maps, after
> classification, with an aggregation of a defined minimum mapping unit(MMU)
> for a scale of 1:50000. As far as I can see, I would say that MMU would be
> minumum size of a polygon that can be mapped. For istance what Would I have
> to do to aggregate a classification map with a minimum area of 20 km^2?

Quick answer without thinking too much:
- r.reclass.area: Reclasses a raster map greater or less than user
specified area size (in hectares).
or
- v.clean, tool rmarea: remove small areas, the longest boundary with
adjacent area is removed

Markus