Vol. XI, No. 1

Spring, 1998

The OpenDWG Alliance

In past newsletters there have been discussion of the AutoCAD file format, the DWG format used by AutoCAD to store CAD models. The last article, "A Problem with AutoCAD Files" explored the problems for scholars that arise when a file format is not securely defined.

Companies in the CAD market have a different problem with the DWG format. It has become so much the standard that companies wishing to compete with AutoCAD are at a competitive disadvantage if they cannot use the DWG format. For instance, the federal government often requires that drawings be submitted in DWG format.

As a result, there have been attempts to produce software tools that would enable CAD producers to read and write DWG files, thus using AutoCAD's file format. One of those companies, Sirlin, was purchased by Autodesk; another, MarComp, was purchased by Visio Corporation. At the time of the purchase Visio did not have a CAD product, but it was nearing the completion of its new CAD program, IntelliCAD.

Surprisingly, Visio decided to make the MarComp tools for reading and writing DWG files public. Visio and other CAD producers founded the OpenDWG Alliance, a non-profit foundation intended to make the DWG file format public. More than twenty other CAD producers joined in the work, not Autodesk or Bentley Systems (maker of Microstation®).

The OpenDWG Alliance placed a full-page advertisement in the Wall Street Journal as one of its first acts, and it maintains a Web site to explain the aims of the Alliance and to provide related information (www.opendwg.org/).

The tools created by MarComp - and those added to the MarComp tools by other members of the Alliance - may be copied for non-commercial use at no charge and for commercial use at a relatively modest one. In addition, a thorough explanation of the format has been written and published on the Alliance Web site.

Autodesk has pointed out that it already supports many standards for the exchange of drawings from one CAD program to another. Yoav Etiel at Bentley Systems, explaining Bentley's decision not to join the alliance, said " data will rarely exist without accompanying programs." That sentiment suggests that CAD producers do not think about long-term storage of CAD models - either by academics and scholars or by commercial firms. That, of course, does not bode well for the archaeologists and architectural historians who use CAD in the course of their scholarly research.

It remains to be seen whether the OpenDWG Alliance will have any real impact on the CAD market or the DWG file format. It may benefit scholars by opening the DWG format, or it may become a pawn in commercial struggles. Only time will tell. (Sources for this article: OpenDWG Web site; American Institute of Architects Web site, especially THIS CONNECTION DOES NOT WORK!!!! www.e-architect.com/pia/membero/cap/edges3.1/open_dwg.asp from which the quotation was taken; telephone conversations with MarComp/Visio/OpenDWG Alliance officials.)

For other Newsletter articles concerning the applications of CAD in archaeology and architectural history, consult the Subject index.

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