[GRASSLIST:9664] Re: Import Gridded Population of the World

[Markus Neteler]

Karl,

final hint :-)

You may define a custom color table with the rules option
of r.colors (see manual page).

CIESIN's color table for their data can be seen here:
 http://sedac.ciesin.columbia.edu/plue/gpw/index.html?main.html&2
and
 http://sedac.ciesin.columbia.edu/gpw/global.jsp

Cheers

 Markus


On Wed, Dec 28, 2005 at 06:16:40PM +0100, Markus Neteler wrote:
> Karl,
> 
> [ after having received offlist the data]
> ok.
> 
> the problem is that GRASS by default applies
> a linear color table. However, with the megacities
> in Asia and elsewhere, this doesn't quite work
> 
> the solution is to apply a custom color table,
> or, as a first approach, a logarithmic table
> 
> r.colors asds00gialpha1 col=grey.log
> d.rast asds00gialpha1
> 
> Works :-)
> 
> Markus
> 
> On Wed, Dec 28, 2005 at 03:42:42PM +0100, Karl Broich wrote:
> > Markus,
> > 
> > At 11:23 28.12.2005 +0100, you wrote:
> > >Karl,
> > >
> > >did you zoom to the map?
> > 
> > no.
> > 
> > >g.region rast=gpw -p
> > >
> > >Then you may check the statistics (probably just the color
> > >table is non-representative):
> > >
> > >r.univar gpw
> > 
> > total null and non-null cells: 5246208
> > total null cells: 0
> > 
> > Of the non-null cells:
> > ----------------------
> > n: 5246208
> > minimum: 0
> > maximum: 5.85072e-39
> > range: 5.85072e-39
> > mean: 5.68089e-44
> > standard deviation: 2.93343e-42
> > variance: 8.60502e-84
> > variation coefficient: 5163.69 %
> > sum: 2.98031e-37
> > 
> > 
> > >If everything is still zero, please let us know.
> > 
> > It is not exactly zero but very, very small.
> > Is there something wrong with this data? How can I check this?
> > 
> > Just for Information: I used GRASS 6.1 CVS.
> > 
> > Karl
> > 
> > 
> > 
> > 
> > --------------------------------------------------------------------------
> > Dr.-Ing. Karl BROICH			Tel:	+49 / (0) 89 / 6004 2478
> > Universität der Bundeswehr München	Fax:	+49 / (0) 89 / 6004 3858
> > Institut für Wasserwesen
> > Werner-Heisenberg-Weg 39
> > D 85577 Neubiberg
> > --------------------------------------------------------------------------
> > 
> 
> -- 
> Markus Neteler     <neteler itc it>       http://mpa.itc.it
> ITC-irst -  Centro per la Ricerca Scientifica e Tecnologica
> MPBA - Predictive Models for Biol. & Environ. Data Analysis
> Via Sommarive, 18        -       38050 Povo (Trento), Italy

-- 
Markus Neteler     <neteler itc it>       http://mpa.itc.it
ITC-irst -  Centro per la Ricerca Scientifica e Tecnologica
MPBA - Predictive Models for Biol. & Environ. Data Analysis
Via Sommarive, 18        -       38050 Povo (Trento), Italy