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31 Jul 2024 10:21:56 EDT (-0400)
  DEM heightfield questions (Message 1 to 9 of 9)  
From: SharkD
Subject: DEM heightfield questions
Date: 17 Jun 2007 19:05:01
Message: <web.4675bd9ea1f031f9b5a736a20@news.povray.org>
I've downloaded some 1:250,000 scale heightfields from this site:

http://edc2.usgs.gov/geodata/index.php

I was wondering if you could tell me how to scale them so that 1 unit = 1
meter.  Thanks!

-Mike


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From: SharkD
Subject: Re: DEM heightfield questions
Date: 17 Jun 2007 21:40:01
Message: <web.4675e0f25b6dbb05c042460f0@news.povray.org>
I was also hoping you could direct me toward a converter that will convert
250,000 scale DEMs as well as 24,000 scale SDTS DEMs to a format which
POV-Ray can import. I've been searching, but the Web is a mess in this
instance.


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From: RobF
Subject: Re: DEM heightfield questions
Date: 18 Jun 2007 20:40:01
Message: <web.4677255a5b6dbb05f47e593b0@news.povray.org>
"SharkD" <nomail@nomail> wrote:
> I was also hoping you could direct me toward a converter that will convert
> 250,000 scale DEMs as well as 24,000 scale SDTS DEMs to a format which
> POV-Ray can import. I've been searching, but the Web is a mess in this
> instance.

3DEM might work. http://www.visualizationsoftware.com/3dem.html
You can probably save the DEM as an image file. Use it as the input image
for POV-Ray's height_field.

Rob.
---
Rob Fitzel
http://www.fitzel.ca/dart/


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From: SharkD
Subject: Re: DEM heightfield questions
Date: 18 Jun 2007 21:55:03
Message: <web.467736505b6dbb05f850a8b00@news.povray.org>
OK, thanks, I'll try that.

"RobF" <nomail@nomail> wrote:
> 3DEM might work. http://www.visualizationsoftware.com/3dem.html
> You can probably save the DEM as an image file. Use it as the input image
> for POV-Ray's height_field.
>
> Rob.
> ---
> Rob Fitzel
> http://www.fitzel.ca/dart/


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From: Leroy
Subject: Re: DEM heightfield questions
Date: 18 Jun 2007 23:30:22
Message: <46774CEF.3080001@joplin.com>
If the others didn't help I've got DEM2POV v1.2a.
I'll be willing to send it to ya.
I don't remember where I got it and I had to fix the cutting function.
It's a window DOS program.


DEM2POV v1.2a:
Converts USGS Digital Elevation Model data files to tga height-field for
POV raytracer. converted W. D. Kirby, 30 mar 96. hacked from dem2xyz.c
18 apr 95. converts 3 arc second to lat/long, sol katz, mar. 94. added
sampling and cutting to size, sol katz, apr 94. changed the calculation
of start position in sampling code, sol katz, jan 95.


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From: SharkD
Subject: Re: DEM heightfield questions
Date: 19 Jun 2007 00:15:02
Message: <web.467757485b6dbb05f850a8b00@news.povray.org>
I tried using that program, but couldn't get it to work. It keeps telling me
that it can't read the input file. I emailed the author, but haven't
received a reply yet.

Leroy <lrw### [at] joplincom> wrote:
> If the others didn't help I've got DEM2POV v1.2a.
> I'll be willing to send it to ya.
> I don't remember where I got it and I had to fix the cutting function.
> It's a window DOS program.
>
>
> DEM2POV v1.2a:
> Converts USGS Digital Elevation Model data files to tga height-field for
> POV raytracer. converted W. D. Kirby, 30 mar 96. hacked from dem2xyz.c
> 18 apr 95. converts 3 arc second to lat/long, sol katz, mar. 94. added
> sampling and cutting to size, sol katz, apr 94. changed the calculation
> of start position in sampling code, sol katz, jan 95.


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From: Leroy
Subject: Re: DEM heightfield questions
Date: 19 Jun 2007 23:22:53
Message: <46789CAC.4040504@joplin.com>
SharkD wrote:
> I tried using that program, but couldn't get it to work. It keeps telling me
> that it can't read the input file. I emailed the author, but haven't
> received a reply yet.
> 
I rework that program a long time ago. I can't remember just what I did 
to it. I run win98 and my version works for me.
I also wrote the author telling him of my fixes and never heard from him.


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From: SharkD
Subject: Re: DEM heightfield questions
Date: 21 Jun 2007 04:35:01
Message: <web.467a37dc5b6dbb0596f3cfc0@news.povray.org>
Leroy <lrw### [at] joplincom> wrote:
> SharkD wrote:
> > I tried using that program, but couldn't get it to work. It keeps telling me
> > that it can't read the input file. I emailed the author, but haven't
> > received a reply yet.
> >
> I rework that program a long time ago. I can't remember just what I did
> to it. I run win98 and my version works for me.
> I also wrote the author telling him of my fixes and never heard from him.

I want to build a road across my heightfield. What's the best way of going
about doing this? It seems a complex process that involves modifying a
high-resolution heightfield image, or converting the heightfield into a
mesh and editing it as well as the road in an external application.


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From: millican
Subject: Re: DEM heightfield questions
Date: 6 Sep 2007 13:39:59
Message: <46e03b6e@news.povray.org>
SharkD wrote:

> Leroy <lrw### [at] joplincom> wrote:
>> SharkD wrote:
>> > I tried using that program, but couldn't get it to work. It keeps
>> > telling me that it can't read the input file. I emailed the author, but
>> > haven't received a reply yet.
>> >
>> I rework that program a long time ago. I can't remember just what I did
>> to it. I run win98 and my version works for me.
>> I also wrote the author telling him of my fixes and never heard from him.
> 
> I want to build a road across my heightfield. What's the best way of going
> about doing this? It seems a complex process that involves modifying a
> high-resolution heightfield image, or converting the heightfield into a
> mesh and editing it as well as the road in an external application.

I've used Terragen to convert DEM files to something (heightfield or mesh?)
for POV. As for the road, you can create a spline from a 2d scan of
something like a road map, create differnet points along the spline, use
the trace function to retrieve the "elevation" from your heightfield at
that point of the road. The smaller the intervals of the points and/or
connectors between the points that make up the spline road, the more
accurate and fluid it will appear. If you're still interested, I have a
file or rendered image at home that I could send or post.


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