AutoCAD DXF

AutoCAD DXF (Drawing Interchange Format, or Drawing Exchange Format) is a CAD data file format developed by Autodesk^[1] for enabling data interoperability between AutoCAD and other programs.

DXF was originally introduced in December 1982 as part of AutoCAD 1.0, and was intended to provide an exact representation of the data in the AutoCAD native file format, DWG (Drawing), for which Autodesk for many years did not publish specifications. Because of this, correct imports of DXF files have been difficult. Autodesk now publishes the DXF specifications^[2] on its website for versions of DXF dating from AutoCAD Release 13 to AutoCAD 2010.

Versions of AutoCAD from Release 10 (October 1988) and up support both ASCII and binary forms of DXF. Earlier versions support only ASCII.

As AutoCAD has become more powerful, supporting more complex object types, DXF has become less useful. Certain object types, including ACIS solids and regions, are not documented. Other object types, including AutoCAD 2006's dynamic blocks, and all of the objects specific to the vertical-market versions of AutoCAD, are partially documented, but not well enough to allow other developers to support them. For these reasons many CAD applications use the DWG format which can be licensed from AutoDesk or non-natively from the Open Design Alliance.

File structure

ASCII versions of DXF can be read with a text-editor. The basic organization of a DXF file is as follows:

• HEADER section – General information about the drawing. Each parameter has a variable name and an associated value.
• CLASSES section – Holds the information for application-defined classes whose instances appear in the BLOCKS, ENTITIES, and OBJECTS sections of the database. Generally does not provide sufficient information to allow interoperability with other programs.
• TABLES section – This section contains definitions of named items.

Application ID (APPID) table

Block Record (BLOCK_RECORD) table

Dimension Style (DIMSTYPE) table

Layer (LAYER) table

Linetype (LTYPE) table

Text style (STYLE) table

User Coordinate System (UCS) table

View (VIEW) table

Viewport configuration (VPORT) table

• BLOCKS section – This section contains Block Definition entities describing the entities comprising each Block in the drawing.
• ENTITIES section – This section contains the drawing entities, including any Block References.
• OBJECTS section – Contains the data that apply to nongraphical objects, used by AutoLISP and ObjectARX applications.
• THUMBNAILIMAGE section – Contains the preview image for the DXF file.
• END OF FILE

The data format of a DXF is called a "tagged data" format which "means that each data element in the file is preceded by an integer number that is called a group code. A group code's value indicates what type of data element follows. This value also indicates the meaning of a data element for a given object (or record) type. Virtually all user-specified information in a drawing file can be represented in DXF format."^[3]

See also

• LibreDWG
• .dwg (DWG)
• ArcMap
• Autodesk
• AutoCAD
• CAD
• DWF
• List of EDA companies
• OpenDWG
• QCad
• VoluMill

References

1. ^ FAQS.org
2. ^ DXF specifications, http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=12272454&linkID=10809853 
3. ^ "Chapter 1 -- DXF Format" Autodesk.com

External links

• DXF Specifications – Autodesk documentation on versions of DXF from Release 13 to current.
• Open Design Alliance – Non-profit industry consortium which provides program libraries to read and write DWG and DXF files.
• Open Source DXF Viewer and Editor – Read, write, and draw to DXF files, export to image, print, zoom, pan.
• Kabeja – Open Source Java library for parsing, processing and converting DXF format. Can convert to SVG, PDF and others.
• Free On-line DXF viewer – an on-line viewer for DXF and other CAD format files. No registration is required.
• Free DXF viewer – a DXF viewer provided by SEW, supports Windows and DOS—Warning: Uninstaller does not work on Vista x64
• de·caff DXF Viewer – a free Java based DXF viewer, supporting 3D and saving as SVG, PDF and bitmap formats
• DXF Sharp Viewer – a free for personal use .NET based DXF/DWG viewer for Windows, supporting 3D and saving as SVG
• Total PDF to DXF Converter – a reliable converter to convert PDF to DXF.
• List of structural engineering software with DXF output
• Konvertor – a browser / converter to convert vectors and rasters formats to and from DXF.