RE: Formats for tesselated data

From: Anshuman Razdan (
Date: Fri Jul 23 1999 - 05:16:48 EEST

This in addition to Ping's comments...

Actually VRML and OpenInventor support more than tesselated data or
trinagulated data. You can have objects of type NURB curves/ surfaces etc
and other algebraic shapes such as spheres, cylinders etc.

Just like all code written in any code gets converted to assembly and then
machine code.... for every practical use - such as rendering on computer
screen, machining, milling - all 3D forms are converted or tesselated. RP
being one such example. You are right tesselation is done per application
and that is not always a bad thing. If you are using it for redering shaded
model you dont want to tesselate below the pixel resolution for it wont be
incorrect geometrically but lose rendering speed. However, the same mode
when RPed at large scale may need higher tesselation but if only 1/10th
scale is being created a smaller tesselated model may be just as accurate.

        Ping offers some tools in her email. Having a history for solid modeling is
not that straight forward. Consider the tesselated model to be equivalnet to
the BREP or Boundary Representaion in SOlid Model. There are many
Constructive Solid Geometry building steps one can use to make the same
final model - I wont bore you with examples. Once a BREP model - it is
possible to arrive at a history solution which may be correct but not the
right one.


Dr. Anshuman Razdan
Technical Director PRISM
MC 5106 Arizona State University
Tempe AZ 85287-5106
Phone: (602) 965 5368
Fax: (602) 965 2910

-----Original Message-----
From: []On Behalf Of
Geiger, Martin (EP/QFM)
Sent: Thursday, July 22, 1999 5:44 AM
To: ''
Subject: Formats for tesselated data

The use of tesselated data for different applications is rapidly increasing.
So, there are different file formats for different applications.

STL for RP
OpenInventor for Visualiziation
VRML for Internet

One disadvantage is that the tesselation is typically done separat for every
Is there any experience in storing tesselated data in EDM/PDM systems
parallel to CAD data?
Are there any tools to convert the data between the formats. I would prefer
macros, without download of the data into a visualization system like CAD.


Martin Geiger
DaimlerChrysler AG
Dep. EP/QFM (Technology Team)
House Post Code: B652
D-71059 Sindelfingen
Phone: +49 (0) 7031 90 82572
Fax: +49 (0) 7031 90 81978

For more information about the rp-ml, see

For more information about the rp-ml, see

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