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High!
As some of you here around may know, I'm striving for a "PoVghanistan"
since several years... that means firstly, I'm looking for a decent
heightfield of the country to model its topography. After some search,
I've fond that gorgeous 21600 by 10800 pixel 8 bit-greyscale map of
Earth (in simple cylindrical projection), cut out Afghanistan and its
close neighbourhood - but at only 2 kms per pixel, the whole thing has
to be greatly exaggerated in height, it's far from looking realistic.
Meanwhile, I started scanning topographic maps from the 1970s at
1:300.000 scale... extracting their 25 ... 50 ... 100 metre-interval
contour lines manually is cumbersome work, not to mention interpolating
the height levels in between. I calculated that, working 8 hours each
day, 7 days a week on this titanic heightfield task, I'll be finished
with entire Afghanistan by 2098 - unless I find a way to automatize the
interpolation process!
Is there any way to obtain publicly accessible elevation data
(preferably 16bit) of Afghanistan at a higher resolution than the 30"
DEMs (perhaps like the 3" USA DEMs with about 100 m/pixel)?
See you in Khyberspace!
Yadgar
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I've been doing the same thing for a place near where I live, and was going
to ask the same question - whats the easiest way to make a heightfield from
a contour map?
jim
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James and Yadgar,
I just had an idea for making height fields from contour maps. You
could scan the maps, then use a paint program such as photoshop to create
gradations. You would have to create a pallete with a different shade of
gray for each height interval. You could then select the section to be
shaded using a magic wand tool, expand the selection by a bit to overlap the
lines, and fill it in with the corresponding tone on a separate layer.
After they are all filled you could use a median filter to blend the
gradation together to get a continuous surface. This process would go
faster on a flatter landscape of course, like where I live in the midwest.
I could see this taking a few days for a 10000x10000 pixel, several square
kilometer map, not years like Yadgar was projecting for his method. This
might speed the process up a bit, but as far as automation, I just don't
know. If you aren't afraid of a little tedium, I say go for it.
-Ben Scheele
"James Taylor" <jim### [at] blueyonder couk> wrote in message
news:3e6545c0@news.povray.org...
> I've been doing the same thing for a place near where I live, and was
going
> to ask the same question - whats the easiest way to make a heightfield
from
> a contour map?
>
> jim
>
>
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James Taylor wrote:
>
> I've been doing the same thing for a place near where I live, and was going
> to ask the same question - whats the easiest way to make a heightfield from
> a contour map?
This matter has been discussed before, see:
Subject: Topographic map to height field?
Date: Fri, 01 Mar 2002 08:36:01 -0500
From: "Timothy R. Cook" <tim### [at] scifi-fantasycom>
Organization: Bellsouth
Newsgroups: povray.general
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______
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Bah I lost all my bookmarks, but there are very much higher resolutions available
freely on the net. You just have to keep looking. I remember seeing 100m resolution
for USA. Something less than that for ROTW. Some people even have cloud maps.
Lucky really that I can't tell you the URL, it would make it too easy ;)
Simeon
On Tue, 04 Mar 2003 23:57:03 +0000
Yadgar <yad### [at] tiscalinetde> wrote:
> High!
>
> As some of you here around may know, I'm striving for a "PoVghanistan"
> since several years... that means firstly, I'm looking for a decent
> heightfield of the country to model its topography. After some search,
> I've fond that gorgeous 21600 by 10800 pixel 8 bit-greyscale map of
> Earth (in simple cylindrical projection), cut out Afghanistan and its
> close neighbourhood - but at only 2 kms per pixel, the whole thing has
> to be greatly exaggerated in height, it's far from looking realistic.
>
> Meanwhile, I started scanning topographic maps from the 1970s at
> 1:300.000 scale... extracting their 25 ... 50 ... 100 metre-interval
> contour lines manually is cumbersome work, not to mention interpolating
> the height levels in between. I calculated that, working 8 hours each
> day, 7 days a week on this titanic heightfield task, I'll be finished
> with entire Afghanistan by 2098 - unless I find a way to automatize the
> interpolation process!
>
> Is there any way to obtain publicly accessible elevation data
> (preferably 16bit) of Afghanistan at a higher resolution than the 30"
> DEMs (perhaps like the 3" USA DEMs with about 100 m/pixel)?
>
> See you in Khyberspace!
>
> Yadgar
>
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