[GRASSLIST:446] dem rescale

Hello,

is there a way to display all values of a dem? the original range was 1-65000
(export from ERDAS), but only values up to 255 are displayed in the monitor
even though d.what.rast is prompting values for the white areas. Nviz is
showing these values above 255 as plateau.
When I rescaled the dem to values between 1-255 the whole image can be seen
but in a pretty coarse resolution in nviz.
When I visualize it in ERDAS I get a better 3D image and I can recognize
valleys.

any idea how to display all values?

thanks in advance, cheers Martin

Hi

Are you working in a UTM Projection?

Does r.describe -r reveal a range of 1-65000 or 1-255?

What color table are you using on the import file? If it's grey.eq, all
values above 255 will appear white. Try changing the color table to
grey/gyr/ryg and try again. Should work.

Sujoy

-----Original Message-----
From: owner-GRASSLIST@baylor.edu [mailto:owner-GRASSLIST@baylor.edu] On
Behalf Of Martin Wegmann
Sent: Friday, June 20, 2003 11:07 PM
To: GRASSLIST(engl)
Subject: [GRASSLIST:446] dem rescale

Hello,

is there a way to display all values of a dem? the original range was
1-65000
(export from ERDAS), but only values up to 255 are displayed in the
monitor
even though d.what.rast is prompting values for the white areas. Nviz is

showing these values above 255 as plateau.
When I rescaled the dem to values between 1-255 the whole image can be
seen
but in a pretty coarse resolution in nviz.
When I visualize it in ERDAS I get a better 3D image and I can recognize

valleys.

any idea how to display all values?

thanks in advance, cheers Martin

hello,

Are you working in a UTM Projection?

Yes UTM WGS84

Does r.describe -r reveal a range of 1-65000 or 1-255?

r.desrcibe shows a range of 1-65280

What color table are you using on the import file? If it's grey.eq, all
values above 255 will appear white. Try changing the color table to
grey/gyr/ryg and try again. Should work.

I changed with r.colors the color table to ryg but still only a minority of
the pixels are displayed (the same as before)
d.profile didn't show as well the other values
d.what.rast is still prompting the values for the "white" areas (all above
255).and nviz is visualizing the values above 255 still as plateau.

further ideas what might be wrong?

thanks Martin

Sujoy

-----Original Message-----
From: owner-GRASSLIST@baylor.edu [mailto:owner-GRASSLIST@baylor.edu] On
Behalf Of Martin Wegmann
Sent: Friday, June 20, 2003 11:07 PM
To: GRASSLIST(engl)
Subject: [GRASSLIST:446] dem rescale

Hello,

is there a way to display all values of a dem? the original range was
1-65000
(export from ERDAS), but only values up to 255 are displayed in the
monitor
even though d.what.rast is prompting values for the white areas. Nviz is

showing these values above 255 as plateau.
When I rescaled the dem to values between 1-255 the whole image can be
seen
but in a pretty coarse resolution in nviz.
When I visualize it in ERDAS I get a better 3D image and I can recognize

valleys.

any idea how to display all values?

thanks in advance, cheers Martin

Martin Wegmann said:

hello,

Are you working in a UTM Projection?

Yes UTM WGS84

Does r.describe -r reveal a range of 1-65000 or 1-255?

r.desrcibe shows a range of 1-65280

What color table are you using on the import file? If it's grey.eq, all
values above 255 will appear white. Try changing the color table to
grey/gyr/ryg and try again. Should work.

I changed with r.colors the color table to ryg but still only a minority
of
the pixels are displayed (the same as before)
d.profile didn't show as well the other values
d.what.rast is still prompting the values for the "white" areas (all above
255).and nviz is visualizing the values above 255 still as plateau.

further ideas what might be wrong?

Just to make sure: what messages about numbers of colors do you see when
you launch d.mon.
As an example, I have:

GRASS:~ > d.mon x0
using default visual which is TrueColor
ncolors: 16777216

Moritz

Hello,

Just to make sure: what messages about numbers of colors do you see when
you launch d.mon.
As an example, I have:

GRASS:~ > d.mon x0
using default visual which is TrueColor
ncolors: 16777216

Moritz

I had a different value for ncolors:

using default visual which is TrueColor
ncolors: 65536
Graphics driver [x0] started

I changed it to 16.8 mio. in my os (linx suse 8.1) settings and get now the
same ncolors output as you, but I've still the same problem with the
visualization of the dem.

Martin