RE: [rp-ml] Re: STL feature recognition

Well this is not a simple matter because STL file only contains
triangles and you will first have to do feature recognition/segmentation
-- you can read the vast literature on the subject from journals such as
CAD. This is not an easy task -- when is a hole a hole? Imagine a circle
made up of vast number of st. lines. Visually it would look like a
circle but how would you recognize algorithmically -- now extend the
problem to 3D and you can see the challenges .. What happens when the
resolution of the circle decreases -- so its only 6 hexagonal segments
-- would you still call it a circle? This is not a parametric or BREP
representation as your traditional solid modeler.

Also you are confusing IGES .. as a file format and what usually you get
in IGES when you save a solid model data.

IGES can contain just a triangle mesh like STL file -- so you have to do
feature recognition there also. However, most of the time you may be
encountering BREP representation.

Dr. Anshuman Razdan
Director PRISM
ASU

-----Original Message-----
From: owner-rp-ml@rapid.lpt.fi [mailto:owner-rp-ml@rapid.lpt.fi] On
Behalf Of Pooyan Jamshidi
Sent: Monday, October 25, 2004 11:15 PM
To: rp-ml@rapid.lpt.fi
Subject: [rp-ml] Re: STL feature recognition

What I actually want to do is to write a piece of code that can
automatically interrogate a STL file and extract info on geometric
features such a diameter or length of a hole or its distance from edge
of the part. The extracted data then had to be transferred
automatically to another file.
Is there any way I can interrogate STL file for this purpose?
I guess a STL file is much harder to interrogate than an IGES file
format!!!!
Received on Tue Oct 26 08:48:56 2004