[GRASS-user] Landsat classification with CORINE CLC color codes?

[Hamish]

> > Dimos wrote:
> > > > > 44 CORINE CLC RGB  color codes are mentioned for each of the 44
> > > > > land use classes at:
> http://dataservice.eea.europa.eu/download.asp?id=14234&filetype=.csv
> > > > >
> > > > > Can we classify a Landsat RGB image based on these rgb color
> > > > > codes in GRASS GIS and how?
> > 
> > Markus: 
> > > > In my opinion it doesn't make much sense to use the RGB colors
> > > > here since they are arbitrary (well, ok, ideally "close" to
> > > > natural colors).

Hamish:
> > I am trying to understand; there are 256^3 RGB possibilities (@ 8bits
> > per channel) and CORINE have selected 44 of those possibilities to
> > give labels to? Your chances of hitting those exactly are rather
> > low. I suppose these are meant to be 3D spectral peaks somehow with
> > the land-use category doing like a 3D form of a nearest-neighbor
> > thiessen polygon.
> > 
> > It seems a rather lossy and sensitive approach, ie it would be better
> > to base it on all 7 bands & include some method to remove time of
> > day/luminance issues. e.g. specify color normalization step first
> > [eg i.landsat.rgb], or convert LANDSAT r,g,b pseudo-visual bands to
> > HIS and classify on that (I'm guessing that hue would be less
> > sensitive to sun angle).

Nikos: 
> Hmmm??
> 
> Maybe I am talking nonsense but, I think, the designers must have tried
> to create a color scheme that, not only is connected in a way to natural
> colors, but also that makes the land cover classes easy to discriminate
> visually and the whole thing a *nice* looking map. Or maybe not... (?).

so we are looking at this backwards?

I answered from the perspective of taking LANDSAT imagery and classifying
it into those 44 categories based on imagery ground color. But perhaps
those colors are meant for people who have categorical data layer (44 cats)
and want to display it in a consistent & pretty way. In that case all that
needs to be done is to reformat the CSV file to pass to r.colors.


In the other direction, if you have a land-use map given in those colors
and which you wish to attach cat numbers/labels to them, & then use them
as training areas for classifying other LANDSAT imagery, that is another
task.


> By the way, below are the official rgb combinations for use
> with "\usepackage{colortbl}" (LaTeX).

how does that relate?


Hamish