Thursday, 22 December 2016

DXF File Format

  • DXF stands for drawing exchange format, first created in 1982.
  • It is created to exchange drawing between different CAD programs like AutoCAD, Adobe Illustrator, Scan2CAD and CoreICAD.
  • DXF can act as a conduit between different vector graphics programs. For example, a file could be created in AutoCAD, saved as a DXF and opened in Adobe Illustrator.
  • DXF file can be opened in any text editor, to see the drawing units.



File Structure

ASCII version of DXF can be read with any text editor. The basic organization of a DXF file is as follows:-
  • Header section: It contains general information about the drawing. For eg. which AutoCAD version the file uses.
  • Classes section: Holds the information for application-defined classes, appears in the Blocks, Entities, and Objects section of the database.
  • Tables section: This section contains definitions for several different tables, each of which contains a number of different symbol entries. For eg. Application ID (APPID) table, Block Record (BLOCK-RECORD) table.
  • Blocks section: This section contains Block definitions entities describing the entities compressing each Block in the drawing.
  • Entities section: It contains the drawing entities, including any Block references.
  • Objects section: Contains the data that apply to non-graphical objects. For eg. AutoCAD dictionaries are stored here.
  • Thumbnail-image section: Contains the preview image for the DXF file.


Advantages

  • DXF file is an open source file format.
  • DXF file is supported by all the CAD programs.
  • It is easily exchangeable across formats.
  • It is compatible with vector file format.

Disadvantages

  • DXF does not support application specific CAD elements.
  • Complex DXF files can becomes large in size.
  • Some applications can not deal with line widths in DXF Files.

Examples

  • An architectural designer receives a layout design from a subcontractor from a PDF file. He’d convert the PDF file to DXF and load the DXF file for editing CAD.


  • An archaeologist has a database with the XY coordinates of her surveyed sites. She exports the data from her specialized data measurement program and converts it into a DXF file. Then, she can load the DXF file into a CAD software and visualize her findings.

My notes



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