I'm looking for a heightfield for the entire US of A, or at least the contiguous
48 states.  Right now I appear to have two options.

I've done several searches and most of the time I get lots of USGS info... these
are really to high a resolution for my needs.  But I *could* download *all* of
the DEM files and stitch them together then reduce the resolution (ewww... I
don't think I've got the HD space or the memory)

I could also take one of the higher res. whole earth pictures I've found and
just cut out the US.  But the problem with that is two-fold.  1) too *low*
resolution.  2) improper projection for a decent rendering of US (although I
could cut from a mapped spherical isosurface)

Any suggestions?

Thanks,
Michael
--
#macro M(D)#local J=strlen(D);#local _=""#while(J>0)#local _=concat(_,substr(D
,J,1))#local J=J-1;#end _#end sphere{z*9,5pigment{rgb x}}#macro N(D,J)text{ttf
"timrom.ttf"M(D)1,0 translate-J}#end#macro O(E,K)#local _=N(E,K)light_source{-
z*9rgb 1projected_through{_}}#end O("leahciM"<1.6,-.3.9>)O("nosnhoJ"<1.6.9.9>)

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Redbeard wrote:
> DEM files and stitch them together then reduce the resolution
> (ewww... I don't think I've got the HD space or the memory)
> Any suggestions?

Try downloading the file, reducing its resolution, THEN stitching
together. ;)

-- 
Tim Cook
http://empyrean.scifi-fantasy.com

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GFA dpu- s: a?-- C++(++++) U P? L E--- W++(+++)>$
N++ o? K- w(+) O? M-(--) V? PS+(+++) PE(--) Y(--)
PGP-(--) t* 5++>+++++ X+ R* tv+ b++(+++) DI
D++(---) G(++) e*>++ h+ !r--- !y--
------END GEEK CODE BLOCK------

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"Timothy R. Cook" <tim### [at] scifi-fantasycom> wrote in message
news:3BECCC49.C86F52A0@scifi-fantasy.com...
> Redbeard wrote:
> > DEM files and stitch them together then reduce the resolution
> > (ewww... I don't think I've got the HD space or the memory)
> > Any suggestions?
>
> Try downloading the file, reducing its resolution, THEN stitching
> together. ;)
>
Well, either way that's a *lot* of downloading... something like 2-10MB per
file, and I'm guessing several thousand files.  Then a *lot* of reducing.  And a
*lot* of stitching.  Not that I'd be entirely against doing it, but I'd like to
do this project sometime soon, rather than in the next 2-3 years. ;)

Thanks for the correction in my process, though.

Michael
--
#declare R=<8,4,.6>/3;#declare C=function{pattern{object{text{ttf"crystal.ttf"
"MDJ"1,0translate-R/4}}}}camera{location-z*30}box{-R,R pigment{rgbf 1}interior
{media{emission.1density{function{C(x,y,z)}density_map{[0mandel 50color_map{[0
rgb 0][.2rgb x][1rgb x+y]}interior 1,1.5scale 60translate<-33.75,2.85>exponent
4][1rgb<2,2>]}}}}scale 24hollow}// (c) 2001 MDJohnson red### [at] wvadelphianet

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On Sat, 10 Nov 2001 01:53:08 -0500, Redbeard wrote:
> I could also take one of the higher res. whole earth pictures I've found and
> just cut out the US.  But the problem with that is two-fold.  1) too *low*
> resolution.  2) improper projection for a decent rendering of US (although I
> could cut from a mapped spherical isosurface)

What about ETOPO2 (2-minute gridded elevation) or ETOPO5 (5-minute)?

A minute of latitude is about a mile (at the US' latitude, a minute of 
longitude is about 3/4 mile) so the 2-minute data for the US wouldn't be all
that huge (4000x2000?), but probably big enough for a decent-sized image.  
The projection might be a problem, but that's a Simple Matter Of Programming.
If it really is a gridded dataset, plotting it directly will result in 
something that looks like a Mercator projection that's been squished 
vertically somewhat.

-- 
#macro R(L P)sphere{L F}cylinder{L P F}#end#macro P(V)merge{R(z+a z)R(-z a-z)R(a
-z-z-z a+z)torus{1F clipped_by{plane{a 0}}}translate V}#end#macro Z(a F T)merge{
P(z+a)P(z-a)R(-z-z-x a)pigment{rgbt 1}hollow interior{media{emission T}}finish{
reflection.1}}#end Z(-x-x.2y)Z(-x-x.4x)camera{location z*-10rotate x*90}

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Redbeard wrote:
> 
> I'm looking for a heightfield for the entire US of A, or at least the contiguous
> 48 states.  Right now I appear to have two options.
> 
> I've done several searches and most of the time I get lots of USGS info... these
> are really to high a resolution for my needs.  But I *could* download *all* of
> the DEM files and stitch them together then reduce the resolution (ewww... I
> don't think I've got the HD space or the memory)
> 
> I could also take one of the higher res. whole earth pictures I've found and
> just cut out the US.  But the problem with that is two-fold.  1) too *low*
> resolution.  2) improper projection for a decent rendering of US (although I
> could cut from a mapped spherical isosurface)
> 
> Any suggestions?
> 

If 1 km resolution (which is already quite a lot for the whole US),
available at:

http://edcdaac.usgs.gov/gtopo30/gtopo30.html

is not enough, it is difficult, i think there is no free single data set
for the whole country.  

If you want to pay, there is for example:

http://edcnts12.cr.usgs.gov/ned/

Apart from that i right now only see the possibility of putting things
together manually.  A complete list of maps sorted by state is on:

http://edc.usgs.gov/glis/hyper/guide/1_dgr_demfig/states.html

If disk space is the problem, you can reduce size before putting them
together.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:3BECE1DE.67F66FC0@gmx.de...
>
>
> Redbeard wrote:
>
> If 1 km resolution (which is already quite a lot for the whole US),
> available at:
>
> http://edcdaac.usgs.gov/gtopo30/gtopo30.html
>
Oooohhhh... just perfect.  Now I just have to finish the downloads (heh... I'm
downloading the whole world ;-) and get them put together (US first... then the
rest of the world if the US render works well)

Thanks for the help!

Michael

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