Re: [rp-ml] A QUERY ON STL FILE FORMAT

Ahmed,

It seems to me you would need to extract the vertices from the mesh & or sub-sample perhaps using intersection curves which could be resampled to extract points in the straight sections. you would then probably want export the points in layers in you preferred format(ASCII, HPGL, ISO G-CODE etc..) This could probably all be accomplished by writing a plugin or even scripts in popular CAD pkgs such as Rhino3D. They have a Free SDK as well as free 30 save Eval version that you can use for testing. In addition they provide excellent user & developer support via newsgroups. Alternately you may be able to subsample the mesh using software such as 3D Data Expert from Deskartes which will export a "regular" mesh where the size of triangles have been made uniform, then extract the vertices & export. ...Just a thought.....

Caleb Walker - CAD/CAM - Reverse Engineering - 3D modeling

Lead CAD/CAM
Kreysler & Assoc.
Digital Sculpture Enlargement
Architectural Composites

  From: Ahmed Issa
  To: rp-ml@rapid.lpt.fi
  Sent: Monday, April 26, 2004 9:33 PM
  Subject: [rp-ml] A QUERY ON STL FILE FORMAT

  Hi All,

  I am developing a laser marking system, which is supposed to produce 3D images inside a cubic bulk of glass. I am sure that some of you have seen this kind of souvenirs in the market. The images will be developed in AutoCAD or any CAD software, then exported as STL file. I am going to develop a code to handle the STL file and convert it into (X, Y, Z) points that resemble the 3D shape. The laser beam will be focused within the work piece at the specific coordinates, thus allowing it to internally vaporize a spot of the material leaving a hollow spherical spot (VOXEL in the order of micons) in a phenomenon known as micro-fabrication or internal marking. The voxels are not connected, however so close so that they form a 3D image. As I understand, this process falls under Steriolithography (p lease correct me if mistaken in categorizing the process).

  The problem I am facing with STL file format that it randomly sorts the facets. I can have control over some parameters such as the resolution of facets but some shapes are not properly tessellated (i.e. big triangles such as the case of cubic shapes).

  My question is: does any one know good reference books or websites on this technique, specifically on how to manipulate STL files. Also on sorting the points in space so as to optimize the travel distance of the XYZ positioning bed?

  Any hints or useful information will be highly appreciated, thanks.

  Ahmed Issa.

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Received on Tue Apr 27 18:23:34 2004