Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!ucsfcgl!pixar!thaw
From: thaw@pixar.UUCP (Tom Williams)
Newsgroups: comp.graphics
Subject: Terrain Rendering (Re: How did Alliant do this image)
Message-ID: <5970@pixar.UUCP>
Date: 14 Jul 89 16:41:45 GMT
Reply-To: thaw@pixar.UUCP (Tom Williams)
Organization: Pixar -- Marin County, California
Lines: 64


  > [Frank Vance writes]
  >(pages 6-7) Alliant features 4 images showing "typical" applications.
  >The one on the right, captioned "Mission Planning" shows an image of a
  >landscape, with valley, river, and mountains.  It has something of a fractal
  >character to it.

Hmmm, though I can't be absolutely positive this sounds exactly like
an animation that we did when I worked at a TASC (The Analytic Sciences
Corporation, Reading MA). Later, we did some high-res images for marketing.

The animation was only partly done on an Alliant. All of the rendering 
and some image processing was done on PIXAR Image Computers.  The Alliant 
did all the heavy-duty IP, including some particularly nasty natural 
coloration.  (BTW, TASC provides mission planning software and analysis, 
BUT that picture was done for ABC's coverage of the Calagary Winter 
Olympics.)


  >1. Is this image just a fractal landscape, or does the image represent a	
  >"reconstruction" of a real-world location based on data points with 
  >elevation, etc.

The latter. The animation runs from the city of Calgary, along the
Bow (sp?) river valley, into the Canadian rockies, to finish at the 
sites where the downhill was held and the site where the cross country 
events were held. (Both endings were rendered and broadcast as seperate 
animations)


  >2. If the latter, how is the real landscape modeled?  As contour lines or
  >discrete points (or a grid)?  The detailing of the mountain (in particular) 
  >seems to imply either a very high level of detail for the model or some 
  >degree of fractal "interpolating" to add texture to the landscape.  

Ah well, that would be telling... The elevation was originally represented
as a sparse contour set.  With adaptive, heat diffusion techniques
the data was converted to a regular grid with 10m resolution. The color
data was originally SPOT satellite data (10m res).  This was put through a 
custom natural coloration algorithm and the results were fine tuned.  
Then the two data sets, the natural color and elevation, where registered.
The Alliant was great for this because the data set was immense 5k x 5k 
pixels ( Actually it's isn't so immense considering we used 32k x 32k 
images for other things).


  >3. Assuming it is not just a fractal image, is this an application some one
  >markets?

TASC still markets terrain images and animations, but all of the technical 
people who worked on those projects have left. If you're interested in
seeing other results look at the February issue of National Geographic 
(Yellowstone fires), or ask ABC or TASC for a copy of the Calgary Animation. 
Hope this helps.

                                          -thaw-


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Thomas Williams ..!{ucbvax|sun}!pixar!thaw

                         'For a long time I felt without style or grace
                          Wearing shoes with no socks in cold weather'
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