Freeware DEM to VRML 
Author Message
 Freeware DEM to VRML

3DEM70 freeware for Win95/98/NT now provides direct creation
of vrml terrain from freely available US Geological Survey
Digital Elevation Models. VRML 2.0 worlds can be produced for
any location in the United States and most of the rest of
the planet. 3DEM70 will also produce three dimensional terrain
scenes and flyby animations in 24 bit color using OpenGL. The
following data sources are directly supported.

    USGS Digital Elevation Model (DEM) files
    USGS Spatial Data Transform Standard (SDTS DEM) files
    USGS Global 30 Arc Second Elevation Data Set (GTOPO30 DEM)
    NASA Mars Digital Topographic Map (DTM) files
    Any elevation data file organized by rows and columns
    Internally generated Mandelbrot and Julia fractals

3DEM70 scenes can be saved in the following formats.

    JPEG (*.jpg)
    Windows bitmap (*.bmp)
    Height field for POV ray tracing (*.tga)
    Flyby animation (*.mpg)
    LCD flyby animation (*.fly)
    VRML world (*.wrl)
    Binary elevation matrix (*.dat)
    ASCII elevation matrix (*.txt)

3DEM70 allows low resolution real-time flyby of DEM landscapes
using OpenGL. Keyboard controls are used to climb, dive, and
turn in space above the DEM surface. The path through space is
recorded in memory during flight, allowing subsequent creation
of a full resolution mpeg animation along the flight path.

3DEM70 freeware can be downloaded from the 3DEM web page at
http://www.*-*-*.com/



Fri, 06 Jul 2001 03:00:00 GMT  
 Freeware DEM to VRML
Visited your site, it looks great!

Plainly the illustration there isn't a screen-shot of a vrml-world.

May I ask if you used an elevation grid for the vrml maps?

And what size grids will work well  (e.g., 100x100, 200x200 or whatever)?

And did you notice any important browser incompatibilities (or a browser
that worked _very_ well with your program)?

This is very interesting!

- Bob Greer
<This message was both posted on comp.lang.vrml and e-mailed.>


Quote:
>3DEM70 freeware for Win95/98/NT now provides direct creation
>of VRML terrain from freely available US Geological Survey
>Digital Elevation Models. VRML 2.0 worlds can be produced for
>any location in the United States and most of the rest of
>the planet. 3DEM70 will also produce three dimensional terrain
>scenes and flyby animations in 24 bit color using OpenGL. The
>following data sources are directly supported.

>    USGS Digital Elevation Model (DEM) files
>    USGS Spatial Data Transform Standard (SDTS DEM) files
>    USGS Global 30 Arc Second Elevation Data Set (GTOPO30 DEM)
>    NASA Mars Digital Topographic Map (DTM) files
>    Any elevation data file organized by rows and columns
>    Internally generated Mandelbrot and Julia fractals

>3DEM70 scenes can be saved in the following formats.

>    JPEG (*.jpg)
>    Windows bitmap (*.bmp)
>    Height field for POV ray tracing (*.tga)
>    Flyby animation (*.mpg)
>    LCD flyby animation (*.fly)
>    VRML world (*.wrl)
>    Binary elevation matrix (*.dat)
>    ASCII elevation matrix (*.txt)

>3DEM70 allows low resolution real-time flyby of DEM landscapes
>using OpenGL. Keyboard controls are used to climb, dive, and
>turn in space above the DEM surface. The path through space is
>recorded in memory during flight, allowing subsequent creation
>of a full resolution mpeg animation along the flight path.

>3DEM70 freeware can be downloaded from the 3DEM web page at
>http://www.monumental.com/rshorne/3dem.html.



Fri, 06 Jul 2001 03:00:00 GMT  
 Freeware DEM to VRML
Hello Bob,
Thanks for the note.

To see screen shots of example VRML worlds, follow the links to
http://www.monumental.com/rshorne/vrml.html.  You will find six different
worlds there that you can enter.  As you have guessed, these worlds were
created as elevation grids.  The source data are US Geological Survey
digital elevation models (DEMs) which are freely available on the Internet.

The 3DEM program allows you to set the size of the grid to any value you
like to obtain the best tradeoff between surface resolution and world file
size.  My experience is that a square grid of between 200 and 300 points per
side gives the best looking surface without a megabyte sized world file.

My system configuration is Win98, Internet Explorer, and the COSMO VRML
player (Version 2.1).  I haven't tested other browser/player combinations,
so if anyone experiences difficulties I would like to hear about it.

Richard Horne

Quote:

>Visited your site, it looks great!

>Plainly the illustration there isn't a screen-shot of a vrml-world.

>May I ask if you used an elevation grid for the vrml maps?

>And what size grids will work well  (e.g., 100x100, 200x200 or whatever)?

>And did you notice any important browser incompatibilities (or a browser
>that worked _very_ well with your program)?

>This is very interesting!

>- Bob Greer



Sat, 07 Jul 2001 03:00:00 GMT  
 Freeware DEM to VRML
Well, I got it and it rocks!

A few things Richard forgot to mention: this is VRML 97, not VRML
1 -- yes, I know VRML 97 *is* VRML but there are still some tools
out there (and mind you, we're grateful for them) that generate
the old version.

Also not mentioned: you can select the part and amount of the DEM
you want to convert and the angle(s) you want to view it.

And if you play with the color bars a little, you can put in
rivers and lakes, put snow on the mountain tops, and in general
create a darn decent looking VRML world.

Two things that top my wish list -- yes, I know, I'm looking a gift
horse in the mouth, but what the heck.

First, I was born in Pittsburgh.  Anyone who's ever worked with
DEMs can guess what I'm going to say.  For some reason (I blame
it on communists in the government, or perhaps Republicans) the
beautiful confluence of the Monongahela and Allegheny rivers is
chopped into two DEMs (or DDFs, whatever they are -- oh yeah,
3Dem70 doesn't just work with the one-degree DEMs like the
pitiful toy I have on my website; it works with more formats
than you can shake a stick at).  So.  Is there a way to join two
(or more) files and select an area that has some of each?

Second, I discovered on the Monterey world (hey, it's my only
claim to fame, and I'm going to ride it until y'all are sick
of it) that VRML browsers go *much* faster when you chop up the
ElevationGrid into 4 or 8 or (for huge worlds) even 16 pieces.
Could you please think about allowing folks to chop up the
grid?  You can use the texCoord node, so you don't need to
chop the JPEG.

BTW, there are also settings so that you can view the 3D maps
with shutter glasses and even movie-theater style red/blue
3D glasses, which is outstandingly cool.  Additionally, the
program is as well behaved as anything I've seen -- but be
sure to write down the lat and long of the place you're
interested in if you're using one of the big maps because
part of its well-behavedness is that it doesn't load all of
those multimegabyte files into memory at once.

I might suggest, mildly, that you think about using PNGs for
the ocean surface.  I noticed when I did the world from
Shoreham-by-Sea on the South coast of England (between
Brighton and, uh, where Nelson's ship is) there was some
tearing between the two ElevationGrids for the land and the
water.  Making the ocean surface semitransparent gets rid
of that effect -- y'all can try that yourselves, btw; it's
pretty easy to spot the ElevationGrid for the ocean.

And to top it all off, a first rate collection of links to
digital terrain data of all sorts, and maps, and textures.
Much better than mine, but then the whole thing is better
than mine.  Hooray!  At last somebody who knows something
about geography did a tool!

This is a magnificent gift to the VRML community, Richard,
and I'll bet you'll be seeing the results as people's worlds
start looking like the real thing.
--
Bob & Kelly Crispen

"And I observe, when any Yahoo comes from London out of Curiosity [to]
visit me at mine own House, we neither of us are able to deliver our
Conceptions in a Manner intelligible to the other."



Sat, 07 Jul 2001 03:00:00 GMT  
 Freeware DEM to VRML



Quote:
>Well, I got it and it rocks!

>than you can shake a stick at).  So.  Is there a way to join two
>(or more) DEM files and select an area that has some of each?

It's simple enough.  Just remember that the edges overlap and aren't simply
adjacent.  (As I recall.)

Java would be much cleaner, but you could use multidimensional associative
arrays in JavaScript to hold the data.  How you'd get this file data in
there (using just JavaScript) is another question.

Quote:
>Second, I discovered on the Monterey world (hey, it's my only
>claim to fame, and I'm going to ride it until y'all are sick
>of it) that VRML browsers go *much* faster when you chop up the
>ElevationGrid into 4 or 8 or (for huge worlds) even 16 pieces.

What do you mean here?  Very interesting, but... I'm unsure what you mean.

I _thought_ that all the levels of detail (using LOD of course) were loaded
simultaneously in memory, to enable rapid switching between the levels.  Is
this incorrect?

Memory limitations are the big problem, I've found.  The memory needed to
load an elevation grid increased much faster than the edge size (or the
surface area) with larger models.  If it loads fast then it moves smoothly;
if it loads slowly then it moves slowly.

So it seemed reasonable that an LOD'd grid (if that's what you're talking
about), having more data to store at all times than a single grid of the
same size, would move more slowly too.

Well, apparently I'm missing the boat here.

Where is this Monterey world?  I want to go play there for a bit!

- Bob Greer
Greer's Numerical Maps



Mon, 09 Jul 2001 03:00:00 GMT  
 Freeware DEM to VRML

Quote:

> >Second, I discovered on the Monterey world (hey, it's my only
> >claim to fame, and I'm going to ride it until y'all are sick
> >of it) that VRML browsers go *much* faster when you chop up the
> >ElevationGrid into 4 or 8 or (for huge worlds) even 16 pieces.

> What do you mean here?  Very interesting, but... I'm unsure what you mean.

> I _thought_ that all the levels of detail (using LOD of course) were loaded
> simultaneously in memory, to enable rapid switching between the levels.  Is
> this incorrect?

Not LODs.  All you do is chop the ElevationGrid into several
pieces (with appropriate translations) and navigation speeds
way up.  This is true in Cosmo PC, Cosmo SGI, WorldView, and
the version of Community Place I used for testing.

I suspect that VRML browsers have to compute all the faces of
an ElevationGrid, while if you chop it into 4 or 16 different
ElevationGrids the browser can do early frustum culling on the
EGs you can't see.  It's the same thing that happens when you
have a huge IndexedFaceSet versus when you chop it into pieces.

http://ece.uwaterloo.ca/vrml98/vrml/monterey.wrl -- and do please
look at the credits.  Contrary to the impression I must have given
by saying it was *my* claim to fame, there were a *lot* of people
working on that one.  All I did was integrate their cool stuff.

We did make the cover of the proceedings, though, so I guess
we're semi-famous.  Eric Mason did the art for the cover from
screen grabs, and I still remember his cursing about getting a
good shot of the fish -- which turned into cursing me when I
told him their periods were three different prime numbers.

WRT LODs, you're right that they load all at once.  But if you're
tricky, you can put a Switch node tied to a ProximitySensor and
have it do a Browser.createVrmlFromURL() to fetch the LOD object
-- though there seems to be a bug with this in Cosmo Player 2.1
that I haven't chased down.  You can see the code for it in
http://home.hiwaay.net/~crispen/worlds/jit/JustInTimeInline.wrl
and the test case in
http://home.hiwaay.net/~crispen/worlds/jit/test.wrl
If your modem lights blink as you approach the box and before
it turns into a sphere, it's working properly.
--
Bob & Kelly Crispen

"And I observe, when any Yahoo comes from London out of Curiosity [to]
visit me at mine own House, we neither of us are able to deliver our
Conceptions in a Manner intelligible to the other."



Mon, 09 Jul 2001 03:00:00 GMT  
 Freeware DEM to VRML



Quote:
>Well, I got it and it rocks!

>than you can shake a stick at).  So.  Is there a way to join two
>(or more) DEM files and select an area that has some of each?

It's simple enough.  Just remember that the edges overlap and aren't simply
adjacent.  (As I recall.)

Quote:
>Second, I discovered on the Monterey world (hey, it's my only
>claim to fame, and I'm going to ride it until y'all are sick
>of it) that VRML browsers go *much* faster when you chop up the
>ElevationGrid into 4 or 8 or (for huge worlds) even 16 pieces.

What do you mean here?  Very interesting, but... I'm unsure what you mean.

I _thought_ that all the levels of detail (using LOD of course) were loaded
simultaneously in memory, to enable rapid switching between the levels.  Is
this incorrect?

Memory limitations are the big problem, I've found.  The memory needed to
load an elevation grid increased much faster than the edge size (or the
surface area) with larger models.  If it loads fast then it moves smoothly;
if it loads slowly then it moves slowly.

So it seemed reasonable that an LOD'd grid (if that's what you're talking
about), having more data to store at all times than a single grid of the
same size, would move more slowly too.

Well, apparently I'm missing the boat here.

Where is this Monterey world?  I want to go play there for a bit!

- Bob Greer
Greer's Numerical Maps



Tue, 10 Jul 2001 03:00:00 GMT  
 
 [ 7 post ] 

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