Choosing The Right File Format/CAD

Vector files (2D & 3D scalable line drawings)

Vector files present special challenges partly because they are used for everything from 3 dimensional models of aircraft to scalable desktop icons. So to talk about one format for all the different uses would be misleading. Instead we'll break vector file formats down by their purpose.

File type	Reviewed formats
3 Dimensional models (architectural, animation, engineering...)	DWG, DXF, VRML, IFC
2 Dimensional drawings (architectural, engineering...)	SVG, DXF, DWG

3 Dimensional models

3D computer graphics can model or represent almost anything found in the physical world, and much more. Because of the variety of uses progress has been slow on adopting standard formats for exchanging and storing data. Many good programs can import and export in several propriety formats, although the quality of the resulting file can be suspect because in many cases developers have had to experiment and guess their way into how the external format works.

In the fields of architecture, engineering and building, some formats (and families of formats) have begun to emerge as contenders for the role of an industry-wide standards. One such format (are there others?) is the Industry Foundation Classes format (IFC) which is now compulsory for state supported building projects in Denmark and many state supported Finnish projects ref.

Until the adoption of Object Class formats like IFC, the main contenders for being called a standard are the proprietary but open Drawing Exchange Format (DXF) from AutoDesk and the W3C recommendation Virtual Reality Modeling Language (VRML).

Because the use of AutoCAD (an AutoDesk product) is so widespread there has been a very successful attempt at supporting their format in other products. The Open Design Alliance has produced the commercially licensed OpenDWG (DWG format) as a format compatible with AutoCADs own DWG format. Many competitors of AutoCAD now offer support for DWG via this format.

The OpenSource 3D modeling application Blender can export in both DXF and VRML.

2 Dimensional drawings

Two-dimensional vector graphic formats can be divided into two groups. Commercial products like AutoCAD and ArchiCAD use 2D (and 3D) vector information to make highly advanced, multiple layered drawings for architects and engineers.

In the graphics and to some extent the animation industry, formats like the proprietary Flash format and the open source standard SVG are popular. Many Adobe programs use a variety of formats which could well be very good working files in the parent program, but can be a problem to open later when, especially when a copy of that program is no longer available.

(this section needs expansion)

Recommendations

• 3 Dimensional Models: Keep the original working file and make a copies in the DXF (to protect metadata) and VRML (to secure visual elements) formats.
• 2 Dimensional Drawings: Keep the original working file and make a copy in the DXF format or SVG format depending on which is best suited.

References

CAD Standards (not fully incorporated in this section yet)