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RE: CAD Programs

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Dennis:

You've had better luck than I in using DWG files from other CAD programs. There was a review in CADALYST or CADENCE not long ago that tested the DWG file compatibility of a number of CAD programs (sorry, I can't locate the issue at the moment). The reviewer encountered significant problems in all of the programs except for AutoCAD LT. Ralph Grabowski's article "Drawing Translation" in the January 1997 issue of CADENCE does a good job of discussing the many complexities.

In any event, a particular CAD program's DWG file compatibility may be quite adequate for a particular situation (or even more than adequate, as in your examples). But there will be entities, properties, or settings that the CAD program doesn't read and/or write in the way that AutoCAD does. That's the nature of translation. And don't forget that the DWG file is a moving target. How many CAD programs support R14 DWG (or DXF), including the new entity types? Do all of them even fully support R13 DWG? For many people, it's worth a lot not too have to worry about all this stuff.

Yes, each of the CAD programs has customization features. But none has had AutoLISP or the other AutoCAD customization interfaces, which means that they can't run third party applications written for AutoCAD, and they can't use the zillions of little AutoLISP utilities and programs that are available. That apparently will change now that Visio and IMSI are adding AutoLISP emulation, which is a good thing. But then there'll be another compatibility issue (AutoLISP emulation), not to mention ADS and ObjectARX....

I'm not defending Autodesk, AutoCAD, or AutoCAD's price. In many ways Autodesk does have design firms over a barrel - in the same way that Microsoft does vis-à-vis operating systems (and, increasingly, business applications). But that's life. In my view it's usually easier and makes better business sense to use software that's standard and widely supported.

- Mark Middlebrook  73030.1604(--nospam--at)compuserve.com  MarkMid(--nospam--at)pacbell.net