Path: utzoo!mnetor!uunet!husc6!bbn!rochester!cornell!batcomputer!eric
From: eric@batcomputer.tn.cornell.edu (Eric Fielding)
Newsgroups: comp.graphics
Subject: Re: Looking for large ( > 1 mega edges) databases
Message-ID: <4008@batcomputer.tn.cornell.edu>
Date: 10 Mar 88 19:43:19 GMT
Reply-To: fielding@geology.tn.cornell.edu
Distribution: na
Organization: Department of Geological Sciences, Cornell University
Lines: 34

In a recent article blob@calgary.UUCP (Brian Wyvill) wrote:
>In article <235@piring.cwi.nl>, varol@cwi.nl (Varol Akman) writes:
>> I am looking for a large (i.e. more than 1000000 edges) graphics
>> object.  I'll use it for non-profit research purposes--to test an
>> algorithm.
>A lot of people are doing research which involves testing algorithms (such
>as ray tracers) with large objects.   I have seen several papers where the
>authors use objects of only 4 or 5 thousand polygons.  In practice, scenes
>often require hundreds of thousands of polygons and the use of standard
>objects would help in comparing algorithms. [...]
>        Brian Wyvill

I have been torture testing a local ray-tracing program with some *real* data.
It generallyu uses up all of the virtual memory that we have at about 80,000
triangles. The data is the topography of the Central Andes in South America,
and the full data set is about 100,000 grid points, which converts to 
200,000 triangles. I have another topographic data set that is 1200x3600
elevations. Rendering this would require > 8 million triangles. It would
be fairly compact to mail, since one only needs the array of values to
generate the surface. Of course, I would love to see a Gouraud (sp?) shaded
version ;-). 

Has anyone developed algorithms that take advantage of the assumptions one
can make about a surface that is basically a large rectangle with fairly
minor perturbations on it? Seems like it could be rendered much more
efficently by not just treating it as millions of triangles.

If anyone wants some topography to render, let me know. I would like to see
any results, if possible. I can also provide my code for turning it into
colored triangles.

		++Eric Fielding

eric@tcgould.tn.cornell.edu  eric@crnlthry.bitnet  !cornell!batcomputer!eric