RE: Problems with Autodesk products

From: Zheng, Yong (
Date: Fri Feb 06 1998 - 09:00:00 EET


Could you explain futher what those "ACIS dialects" are? When you mention
that ACIS is out of fashion, are you talking the recent transition of
SolidEdge and MicroStation and the running up of SolidWorks? Spatial
claims that ACIS still dominates the Geometric Modeling Kernel market.


 -----Original Message-----
From: Jürgen Bauer
Sent: Friday, February 06, 1998 11:50 AM
To: 'Rod Ward' <>, V;
Subject: AW: Problems with Autodesk products

Yesterday I had lunch with our CAD guru, Dr. Wallner from Janus =
He is teaching us in Unigraphics, but he is not affiliated to EDS.

Me question:
"I have heared that ACIS as a geometry engine went out of fashion. Is =
this true ?"

His answer:
"The problem is, that ACIS has dozens of different dialects now, which =
are incompatible. This makes it hard for third party software suppliers
to write code working for all ACIS dialects. Parasolid, in contrast, =
has only one valid "dialect". The reason for this is, that all new =
functions are tested and certified against each other, and all =
Parasolids customers get the whole new code once a new release comes =
out. Therefore, all Parasolids-based Products like Unigrapics or =
SolidWorks run above an identical geometry core."

In most cases, file interfaces, i.e. for STL, are third party software. =
They are not written by the geometry engine supplier (ACIS, Parasolids),
and - for sure - are not written by the CAD system supplier as well.

Juergen Bauer

Siemens EC CS Automotive, Siemensstr. 13, 67346 Speyer, Germany
Tel. +49 6232 30 2501, Fax +49 6232 30 2110

 -----Urspr=FCngliche Nachricht-----
Von: Rod Ward []
Gesendet am: Donnerstag, 5. Februar 1998 14:03
Betreff: Re: Problems with Autodesk products

On Feb 5, 8:53am, VERN CARTER wrote:

> Subject: Problems with Autodesk products
> [ plain text
> Encoded with "quoted-printable" ] :
I hope someone can help.
> As it turns out, many of our client are using AutoCAD R12 through R14 =
Mechanical Desktop. We have known for some time that these products do =
produce the best IGES or STL files.

The problem lies not with Autodesk but with the ACIS geometry engine. We
developed one of the first interfaces from ACIS .sat (acis neutral file)
stl. We went thru a lot of heartache with features being left off and =
being deleted. We were using native ACIS not Autodesk products. We have =
abandoned all development with Spatial Technology and ACIS. Perhaps =
these kind
of shortcomings are why Solid Edge has abandoned ACIS for Parasolids for
next release!

Rod Ward
Rapid Prototyping Corp.
Longmont, Co.

Rod Ward

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