Re: please help rapid prototyping

From: Ismo Mäkelä (
Date: Wed Nov 19 2003 - 17:47:33 EET

Hello Jonathan,

Please find my answers below.

Jonathan Chertok wrote:

> Ismo,
> Can you talk a little about what kind of problems Deskartes can solve
> with respect to Rhino files? Which commands do you perform most often
> on Rhino files?

When generating triangles from surface models DeskArtes 3Data Expert can
automatically stitch the adjacent faces together so that the result is a
watertight STL model. The stitching is controlled by a user given
tolerance, so even larger cracks can be stitched while triangulating.

3DE can also start from triangulated models and perform similar
stitching and gap filling to STL files.

> Are their certain kinds of errors that you see in Rhino files? If so,
> do you know why?

I am not an expert with Rhino but here are my taughts. Sometimes all
surface edges are not fully stitched together in a Rhino STL file. This
applies specifically to adjacent surfaces which are not intersected
against each other. The problem is probably caused by not using the
correct building methods and can be solved by manual means also in
Rhino. But this can take a long time with large models.

> Do you know what the "bad object" command in rhino selects?

Not really.

> Do you know why Rhino has problems with Boolean Operations and what is
> it about these operations that makes them a more difficult problem
> from a programming standpoint than say other Rhino operations?

Boolean operations between surfaces require rather complicated
mathematical calculations which are prone to accumulating epsilon
errors. Also, with surface modeling it is more difficult to decide the
cut out part of a surface after several intersection operations, which
is rather different in solid modeling.

> Also, would Deskartes need an stl, or could you simply export IGES or
> native Rhino files into Deskartes.

Currently you it is best to use IGES to export Rhino files to 3DE. You
can also use STL but generally it is better to start the correct STL
generation process with surface models in 3DE.

I hope this helps. I would be happy to provide you with a one month
evaluation to 3DE to see what it can really do.

Best regards,


Ismo Mäkelä
Managing Director
DeskArtes Oy     
Pihlajatie 28              tel. +358-9-644 335
FIN-00270 HELSINKI         fax. +358-9-644 330

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