Re: surface to solid

From: Sarvajit S Sinha (
Date: Wed Jul 30 1997 - 01:15:22 EEST

At 11:13 PM 6/2/97 -0500, Welsh_1 wrote:
>Is there any software available to convert surfaced models to solid models
>as painlessly as possible?
>Paul Evans
>Siemens-Furnas Controls

The general answer is NO. And anyone claiming that it is clearly hasn't
dealt with all the problems of a surface model. Much as there is no magic
bullet to close polygonal models and certify that it is a valid .stl
file(see recent RPML message by Rob Roy), there is no magic button which
will correct all the possible defects in a surface model so that export to a
solid modeler is easy.

Possible defects vary from
1) User errors such as duplicate surfaces (e.g. Typical- Leaving the base
surface and its trimmed version in the model)
2) CAD system limitations (e.g. Some CAD systems have no capability to build
surface models while ensuring positional/tangent/curvature continuity,
especially on trimmed boundaries.)
3) Process related problems (e.g. Surface model was built for machining,
where a 0.05mm gap between surfaces will just be skimmed over in the CAM
software; whereas solid modelers require floating-point tolerances on
boundary continuity).

We have built a system, Surfacer, that, by design, deals with these
problems. We can build surface models with appropriate continuity when using
our modeling tools. We can also import IGES files and STITCH surfaces back
together. A number of our customers are using this capability, which we call
HEALING, to repair surface models before export to ProEngineer.

While some of you may argue that this is a non-problem, since it involves a
problem in the design methodology, I would argue that there are too many
such situations for us not to offer a product that resolves some of these

For more information on our product line, see For a
discussion on the issues of surface->solid model transfer, feel free to
contact me.


Dr. Sarvajit Sinha
Imageware Corp.,
USA 323 N.First St, Ann Arbor, MI 48103
        313-994-7301(ph) 313-994-0802(fax)

Europe Coremansstraat 34, 2600 Berchem, Belgium
        (32)3-239-2878(ph) (32)3-239-3330 (fax) (32)95-520503(mobile)

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