MATLAB Central Newsreader - colormap of earth's topography

colormap of earth's topography

Durga Lal Shrestha — Thu, 19 Apr 2012 07:07:31 +0000

Hi

I would like to change colormap of earth's topography as found in following matlab demo.

http://www.mathworks.com.au/products/matlab/demos.html?file=/products/demos/shipping/matlab/earthmap.html

What I want is to have only two color, see (altitude <=0) as white and land (altitude >0) is grey. I have tried using colormap editor, but it is very difficult.

The topo has minimum level of -7473 and maximum level of 5731. I did the following

white=ones(7473,3); % for ocean
l=[0.88 0.82 0.68]; % for land
l=repmat(l,5731,1);
topomap_twocolor = [w;l];
colormap(topomap_twocolor);

I think because of many colormap entry, it displays only white. I tried to decrease the size of entry by factor of 50, but it is not accurate. So does anyone has work around for this?

Thank you very much.

Durga

Re: colormap of earth's topography

Richard Ellis — Fri, 20 Apr 2012 21:07:42 +0000

How about this:

image([0 360],[-90 90],topo,'CDataMapping', 'scaled');
axis image xy
colormap([1,1,1;0.5,0.5,0.5])
caxis([-7473,7473])

"Durga Lal Shrestha" <durgals@hotmail.com> wrote in message
news:jmodjj$iag$1@newscl01ah.mathworks.com...
> Hi
>
> I would like to change colormap of earth's topography as found in
> following matlab demo.
>
> http://www.mathworks.com.au/products/matlab/demos.html?file=/products/demos/shipping/matlab/earthmap.html
>
> What I want is to have only two color, see (altitude <=0) as white and
> land (altitude >0) is grey. I have tried using colormap editor, but it is
> very difficult.
> The topo has minimum level of -7473 and maximum level of 5731. I did the
> following
>
> white=ones(7473,3); % for ocean
> l=[0.88 0.82 0.68]; % for land
> l=repmat(l,5731,1);
> topomap_twocolor = [w;l];
> colormap(topomap_twocolor);
>
> I think because of many colormap entry, it displays only white. I tried to
> decrease the size of entry by factor of 50, but it is not accurate. So
> does anyone has work around for this?
>
> Thank you very much.
>
> Durga

Re: colormap of earth's topography

Durga Lal Shrestha — Tue, 24 Apr 2012 03:26:11 +0000

Thank you very much for the help. I did using "Fill on" option in contour as below

contour(0:359,-89:90,topo,[0 0],'LineColor',[188 164 94]./255,'LevelList',0,'Fill','on');

Durga

"Richard Ellis" <rich@mathworks.com> wrote in message <jmsj72$egh$1@newscl01ah.mathworks.com>...
> How about this:
>
> image([0 360],[-90 90],topo,'CDataMapping', 'scaled');
> axis image xy
> colormap([1,1,1;0.5,0.5,0.5])
> caxis([-7473,7473])
>
> "Durga Lal Shrestha" <durgals@hotmail.com> wrote in message
> news:jmodjj$iag$1@newscl01ah.mathworks.com...
> > Hi
> >
> > I would like to change colormap of earth's topography as found in
> > following matlab demo.
> >
> > http://www.mathworks.com.au/products/matlab/demos.html?file=/products/demos/shipping/matlab/earthmap.html
> >
> > What I want is to have only two color, see (altitude <=0) as white and
> > land (altitude >0) is grey. I have tried using colormap editor, but it is
> > very difficult.
> > The topo has minimum level of -7473 and maximum level of 5731. I did the
> > following
> >
> > white=ones(7473,3); % for ocean
> > l=[0.88 0.82 0.68]; % for land
> > l=repmat(l,5731,1);
> > topomap_twocolor = [w;l];
> > colormap(topomap_twocolor);
> >
> > I think because of many colormap entry, it displays only white. I tried to
> > decrease the size of entry by factor of 50, but it is not accurate. So
> > does anyone has work around for this?
> >
> > Thank you very much.
> >
> > Durga