Group: OpenDWG Replacement

From LibrePlanet
(Redirected from OpenDWG Replacement)
Jump to: navigation, search

On the FSF's High Priority Projects list there is a call for the creation of a replacement for the OpenDWG project and libraries. This includes a free standard for Computer Aided Design (CAD) software. This section of the wiki is to help organize our efforts to either find, customize, or create such a system.

Furthermore we would like to concentrate efforts in the development of a free 3D CAD software. If you are actively developing this kind of software, know about existing project or would like to use such software, please add yourself below. Also feel free to head over to the discussion page, if you are interested in helping with any aspect of this high-priority project.

Helping to collect existing free software CAD software would be a great first step, as well as any work that has been done on this front. This project has an opportunity to not only replace the proprietary formats but also to help progress the field of Computer Aided Design in general.


CAD Software Projects

Please help us collecting existing Computer Automated Design and related software projects.

  • Archimedes is free CAD software built over Eclipse’s Rich Client Platform fully based on plug ins.
  • QCAD an easy to use 2d-CAD, available in a closed source professional and a GPLed community edition. Reads and writes DXF by default.
  • the opencascade project provides a software stack that has many foundations for CAD/FEM/CFD Software. It was started or at least is pushed by airbus - i think to avoid vendor lock-in with long running aeroplane design projects that go on for decades. Derived from this is "salome". We also have pythonOCC is a set of open-source Python bindings for OpenCascade, distributed under the terms the CeCILL Licence
  • avoCADo was recently startet in java. It is in very early stages, aimes for cross plattform use, but i fear java the wrong choice for a demanding piece of software
  • Blender - once had the idea to fork a cad version. However CAD is mainly about 3D geometric driven design and then deriving 2D drawing from it. Blender is about artists expressing there imagination. But - the 3D displaying technology and rendering is there, blenders interface is very theme driven, maybe a starting point.
  • PythonCAD is simple 2D CAD software in Python recently this has been rewritten to improve speed. Best part is Python seems to be right choice for free software.
  • FreeCAD is existing project on written in C and Python seems promising.
  • CADEMIA is simple CAD tool made in JAVA it can import DXF format.
  • Inkscape is a native SVG editor which has as part of it's road map CAD tools inline with technical illustration and traditional 2D CAD activity.
  • libdwg is "An open C library to directly read DWG files, a popular drawing format used in the CAD world." - It tries to read the DWG CAD format of AutoDESK and can be of help for any Free CAD software project. Since the DWG is CAD format used by AutoDESK which is known to have changed their file formats over last 10+yrs (under the same file extension) this project needs lot of support for it has a moving goal. This is as good as OpenDWG which is also providing the libraries for reading DWG formats. Also we need to keep in mind that it was claimed trademark violations involved in such exercise, OpenDWG was sued by AutoDESK. LibDWG is written in C with comments, variable names and datastructures in Esperanto.
  • LibreDWG is a free C library to read and write DWG files. It has been aproved as an official GNU package as of 22nd October, 2009. We have forked LibDWG due to its usage of Esperanto, which we think is not the best strategy for a free software project which aims to get lots of contributors. LibreDWG is written in English. Since we forked LibDWG (May 16, 2009), its development seems to have been inactive. At the moment (September 25, 2009) our decoder is almost done. We are reaching 100% read support in our data structures parser but we still need a test suite. Among the example applications we wrote using LibreDWG is an initial SVG conversion tool. Please contact us if you can help. Sometimes we hang on our IRC channel which is #libredwg at If you dont find us there, please email me: (Felipe Sanches)
  • gCAD3D is a free 3D CAD software under GPL. Has got very good 3D capabilities.

Free file formats

Please help us find existing free formats that could form as a good basis for this project.

There is a partially usable specification of the DWG format by OpenDWG ([1]). However, it is full of errors and omissions, and OpenDWG is not providing any support on this format. The OpenDWG spec is still usable to some extent, but it still needs a considerable amount of work (reverse engineering). Furthermore, every time AutoDesk comes out with a new version, this new version will have to be reverse engineered again. So the crucial ingredient is having sufficient reverse engineering power. When the format is known, implementing it is not such a big deal. Big parts of the object model are known from the DXF specification, which is publicized by AutoDesk (however also containing errors and missing large parts of the complete format [2]).

  • vtk from is a 3D CAD format used in scientific areas
  • - OCF / Open CAD Format Council
  • ISO15926 is an ISO standard which is evolved (& still evolving) based on the need of Oil & Gas Operators. CAD and related linked data needs to be maintained over very long period (usually 25 yrs) for a facility like Refinary. The format is xml based and neutral to any CAD software. This format I understand will enable exchange of CAD data between various cad platforms like PDS/AutoPlant/PlantSpace etc. It is aimed to be a 4D CAD data which will store the history of a Oil & Gas Facility like Refinery over a period of many years. The scope as can be read on the website has now gone beyond the Oil & Gas Industries. This FSF project needs to have closer look at this standard.
  • A BIM model ((Building Information Models)) is a placeholder for the information about a building or a facility, and that can includes also ductwork, electrical installation, fire protection, occupancy, energy consumption, CO2 emissions or whatever information you need to collect regarding a site or a building. A BIM model does not even need to have geometry, only information and still be a BIM. It is known to be used as a 3D model of an architectural design by several proprietary applications such as Revit, Allplan and Archicad.
  • [3] COLLADA. There must be something in this format as google sketchup is supporting

it out of box . . ! Also there is google code project on OpenCollada [4].

  • Note: there should be a consideration for different kinds or cad packages or orientation, electronics, architecture, mechanics, etc.?

Other things are close related to the features, like layers, linetypes, hatchs, the basic object primitives and objects to be represented (blocks, parts libraries) properties like colors, and most important, the units, the precision, and the notation.

Known CAD File Formats

Please add here all the known CAD file formats.

List of Known CAD Formats
Extension Details Status
DGN MicroStation file format proprietary
DWG AutoDesk ACAD file format proprietary
DXF AutoDesk ACAD file exchange format proprietary
FCStd FreeCAD file format Not Checked
igs Not Checked Not Checked
iges Not Checked Not Checked
step Not Checked Not Checked
stp Not Checked Not Checked

This section may move to other page once more info is available.

General Wikipedia page on file formats has the following list:

Sharing CAD files

Please help us find existing libraries or communities providing free CAD files

  • is a internet project driven by a german cabinet maker's workshop [5]. The aim of is to encourage craftsmen and any others operating craftsmanship to share their knowledge, drawings, ooffice templates , ...
  • There's a large library that contains typically drawings of small parts or symbols that are often used in drawings (such as screws, nuts or symbols for electrical schemas) provided by, the autor of QCad. This library is public domain (verified by the owner of ribbonsoft, Andrew Mustun).

3D Design Communities

CA[X] Distributions


3D Printers, Rapid manufacturing & tooling, and various other technologies to "grow" parts are available and will spread in the foreseeable future. Free design communities are there, much like free software communities, but lack software to design and share parts, models, etc. There could be a "youtube" for cad drawings/designs, ranging from mechanical to architecture projects.