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From: Fabien Hénon
Subject: Already converted DEM files
Date: 14 Apr 2000 04:06:55
Message: <38F6D198.696A22FC@club-internet.fr>
Hi you all.

I am planning on rendering afly-by of some parts of the world ( with the
actual reliefs, seas and all).

I downloaded one so-called DEM files but did not manage to get anything

understand my nervousness. All the DEM utilities fail to read it ( and
the file is not corrupted as it is in a normal .tgz format and I can see
its content).

The readme file says :
"The DEM is provided as 16-bit signed integer data in a simple binary
raster.
There are no header or trailer bytes imbedded in the image.  The data
are
stored in row major order (all the data for row 1, followed by all the
data
for row 2, etc.)." ----> I tried to read it as a Raw file, but it
doesn't work. Am I right ?

I tried with a smaller file but no more luck.


Does anyone know if I can find somewhere on the net files which have
already been converted for height_fields use( TGA, PNG,....)

Thanks



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From: Vahur Krouverk
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 05:34:28
Message: <38F6E679.5007B54B@aetec.ee>
Hi!

Look for the following thread in povray.binaries.utilities:
Subject: Problem DEM2POV/DEM2TGA?
Date: Fri, 17 Apr 1998 18:56:57 +1000

I've posted there as response my DEMTOTGA conversion program and source
code. There are links to other conversion programs too.

Hope this helps.


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From: Vahur Krouverk
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 06:06:54
Message: <38F6EE0F.E2B8CE65@aetec.ee>

> 
> Hi you all.
> 
> I downloaded one so-called DEM files but did not manage to get anything

> understand my nervousness. All the DEM utilities fail to read it ( and
> the file is not corrupted as it is in a normal .tgz format and I can see
> its content).
> 
On second thought, are you using DEM files? What do you mean by "normal
.tgz" format? Have you uncompressed and untar-ed it? When I worked with
DEM files, then height information file was 80 MB + there was number of
auxilary files. Seems like you haven't unpacked them...


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From: Fabien Hénon
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 07:48:49
Message: <38F7059A.B6217536@club-internet.fr>
Well, I did untar and uncompressed the files and I got a number of files :
>W020n40.dem     56 Mb
>W020n40.dmw
>W020n40.hdr
>W020n40.prj
>W020n40.sch
>W020n40.src    28 Mb
>W020n40.stx

I give the size for the largest files only. The others are only a few bytes
large.

I read the readme file, but it does not say how to handle the files.


I have the feeling that the DEM file is not a proper one ( The DEM extension
is not correct here).

I downloaded the file from :
http://edcdaac.usgs.gov/gtopo30/gtopo30.html






> >
> > Hi you all.
> >
> > I downloaded one so-called DEM files but did not manage to get anything

> > understand my nervousness. All the DEM utilities fail to read it ( and
> > the file is not corrupted as it is in a normal .tgz format and I can see
> > its content).
> >
> On second thought, are you using DEM files? What do you mean by "normal
> .tgz" format? Have you uncompressed and untar-ed it? When I worked with
> DEM files, then height information file was 80 MB + there was number of
> auxilary files. Seems like you haven't unpacked them...


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From: Vahur Krouverk
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 08:24:03
Message: <38F70E30.CBAE02C2@aetec.ee>

> 
> Well, I did untar and uncompressed the files and I got a number of files :
> >W020n40.dem     56 Mb
> >W020n40.dmw
> >W020n40.hdr
> >W020n40.prj
> >W020n40.sch
> >W020n40.src    28 Mb
> >W020n40.stx
> 
> I give the size for the largest files only. The others are only a few bytes
> large.
> 
> I read the readme file, but it does not say how to handle the files.
> 
> I have the feeling that the DEM file is not a proper one ( The DEM extension
> is not correct here).
> 
> I downloaded the file from :
> http://edcdaac.usgs.gov/gtopo30/gtopo30.html
> 

If my memory serves me correctly, then I've used files from same site
and the set of files seems to be OK. File size is probably OK too, my
memory failed here: whole package was probably >80 MB. Have you tried my
converter (see my previous post)?


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From: Ken
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 09:08:18
Message: <38F717AC.16B7A618@pacbell.net>
Vahur Krouverk wrote:

> If my memory serves me correctly, then I've used files from same site
> and the set of files seems to be OK. File size is probably OK too, my
> memory failed here: whole package was probably >80 MB. Have you tried my
> converter (see my previous post)?

I just downloaded a dem from that site and the two utilities I have for
conversion choked on them too. I then downloaded your utility and while
it was able to read the file and convert it to a .tga image there was
erroneous data in the resulting .tga the rendered it useless to me.
The dem I downloaded is of the Hawaiian Islands (w180n40.dem) which is
fairly well centered in the data. When converted to tga, with your
utility, there is a green colored stripe going directly through the
island chain (directly in the middle of the image) running left to
right. It takes up a sizable chunk of real estate

Any idea what may be causing that ?

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/


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From: Vahur Krouverk
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 10:49:31
Message: <38F73047.7F640A5@aetec.ee>
Ken wrote:
> 
> The dem I downloaded is of the Hawaiian Islands (w180n40.dem) which is
> fairly well centered in the data. When converted to tga, with your
> utility, there is a green colored stripe going directly through the
> island chain (directly in the middle of the image) running left to
> right. It takes up a sizable chunk of real estate
> 
> Any idea what may be causing that ?
> 
As I wrote in the binaries, I had similar problems (some parts seemed to
be incorrect) and I don't know, whether this is problem in my converter
or data. I'll look at my source.


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From: Vahur Krouverk
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 13:02:31
Message: <38F74F72.CC6D6955@aetec.ee>
Ken wrote:
> The dem I downloaded is of the Hawaiian Islands (w180n40.dem) which is
> fairly well centered in the data. When converted to tga, with your
> utility, there is a green colored stripe going directly through the
> island chain (directly in the middle of the image) running left to
> right. It takes up a sizable chunk of real estate
> 
> Any idea what may be causing that ?
> 
I d-l same file and got same result. As matter of fact, there is red and
green component in this stripe. I think that this is
compression-decompression problem, as it reaches from one high peak to
other. I try in on home computer (linux box) to see, if this helps.


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From: Bob Hughes
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 16:07:09
Message: <38f77a6d$1@news.povray.org>
Check out the FAQ there, this type of DEM is not ASCII.
http://edcdaac.usgs.gov/gtopo30_faq.html

Bob

|
| I read the readme file, but it does not say how to handle the files.
|
|
| I have the feeling that the DEM file is not a proper one ( The DEM extension
| is not correct here).
|
| I downloaded the file from :
| http://edcdaac.usgs.gov/gtopo30/gtopo30.html
|


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From: Fabien Hénon
Subject: Re: Already converted DEM files
Date: 14 Apr 2000 16:26:10
Message: <38F77ED9.C7DC260C@club-internet.fr>
So, is there a way I can convert this 'simple binary raster format' ? With
Photoshop 5 maybe.
I have to say that I have never heard of this file format.

If anyone knows if/how it can be converted. I tried to open it as a RAW  file with
different options, but all I get is a blurry image.


Thanks






> Check out the FAQ there, this type of DEM is not ASCII.
> http://edcdaac.usgs.gov/gtopo30_faq.html
>
> Bob
>
> |
> | I read the readme file, but it does not say how to handle the files.
> |
> |
> | I have the feeling that the DEM file is not a proper one ( The DEM extension
> | is not correct here).
> |
> | I downloaded the file from :
> | http://edcdaac.usgs.gov/gtopo30/gtopo30.html
> |


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