Re: [GRASS-user] Defining Minimum Mapping Units

2010-01-20 Thread Markus Neteler
On Wed, Jan 20, 2010 at 7:03 PM, Luis Lisboa  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 1:5. 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
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[GRASS-user] Defining Minimum Mapping Units

2010-01-20 Thread Luis Lisboa
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 1:5. 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?

Thanks

Best regards
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