Chapter 11: The DWG Format and Its Future

OVERVIEW

CHAPTER SUMMARY

This chapter describes the DWG file format produced by AutoCAD.

You also read thoughts on the future of CAD file formats, the advantages, and the problems the new formats might create.

The DWG file is not documented by Autodesk. When customers ask for documentation on the format, Autodesk points them to its own DXF, the IAI's IFC, Spatial's ACIS SAT, and other documented formats that can represent drawings created by AutoCAD though not with 100% fidelity.

There are times when only direct access to DWG will do, such as for file viewers. Several third-party developers have created toolkits for reading and writing DWG files (a.k.a. APIs). These have been popular with CAD vendors wanting to directly translate AutoCAD drawings without going through an intermediary format, such as IGES and DXF.

RESOURCES

OpenDWF Alliance has documentation of the DWG file format, as well as utilities for handling DWG files:
www.opendwg.org.

Autodesk has documented the DXF specification:
www.autodesk.com/adsk/item/0,,140239-123112-358900,00.html.

IntelliCAD Consortium has a free CAD program that reads and writes DWG files:
www.intellicad.org.

Cyco Software of the Netherlands was the very first to crack the DWG format, back in the late 1980s. They used this knowledge to write a utility to recover damaged DWG files. (This function has since been added to AutoCAD as the Recover command.) Their second product allowed you to view and print AutoCAD drawings without needing AutoCAD.

Another of the third-party developers, Sirlin, was purchased by Autodesk in the mid-1990s because, the rumor went, Autodesk...