Why CGM?

Spatial has been tasked with turning GCM into a kernel for use with stand-alone CAD programs. CGM is short for "Convergence Geometric Modeler," and is the kernel used by Dassault Systemes Catia MCAD software. Why CGM?

Now, Spatial already has ACIS as a licensable kernel, and it is used by many smaller CAD vendors. (Large CAD vendors tend to have sufficient resources to build and control their own kernel.) Archcompetitor Parasolid from Siemens PLM Systems is very popular, and then there are a number of other 3D modeling kernels from smaller companies in the USA and Russia. The question becomes, why does the world need another kernel?

At Spatial's 3D Insider Summit, I had the chance to asked the question of the CGM folks. First off, they are concentrating on promoting CAM and CMM software, not CAD. (CAM is "computer-aided manufacturing", while CMM is "coordinate-measuring machines".)

The most likely use-case is someone who has a plug-in for Catia, and now wants to make it a stand-alone program. Another use-case is a CAD vendor is developing a next generation of software, where it is written largely from scratch; in this case, the CAD vendor might want to consider CGM. In no case would a CAD vendor switch the kernel of an existing progRAM from ACIS to CGM, because the work would be just too hard.

"Does using CGM mean there is not translation needed with Catia?" I asked. Well, no; the application would still need to use InterOp to translate files from CGM format to the part format expected by Catia. The geometry, however, is an exact match. Thus, using CGM means you don't get the problem usually associated with translation, such as mismatched entities and gaps due to differing tolerances.

http://www.spatial.com/products/cgm

 

Comments

[Jon Banquer]

What's needed is an announcement by a CADCAM company not owned by Dassault that they are going to implement the CGM kernel.

Questions I have:

How much of the surfacing functionality that is in Catia is in the CGM kernel?

In a history based modeler can the CGM kernel provide significant speed advantages over Siemens Parasolid by taking advantage of concurrency?

It sure would be nice to see head to head performance comparisons between Siemens Parasolid and Dassault CGM.