Offering proprietary MCAD formats in a while
Recording the conference for broadcast
There are software companies who toil in the background, who are content to remain largely anonymous, and without whom our CAD/CAM/CAE industry would collapse. These firms quietly write programming toolkits, translators, kernels, and even complete programs. They seem quiet because they don’t need to market to the wider design audience -- just to CAD vendors.
- Programming toolkits (aka SDKs, software development kits) make it possible to read, display, edit, and write CAD objects. The most popular ones are for objects defined by Autodesk’s near-universal DWG format, along with Adobe’s 2D/3D PDF and neutral formats like IFC and JT.
- Translators let CAD programs read and write files from competitors and from standardized formats. If a CAD program cannot directly read object data from, such as, a DWG file, then the next best thing is to translate it into something the CAD program can read. Examples include proprietary file formats used by Solidworks and Creo, as well as formats defined by standards organizations, such as STEP and IGES.
- Kernels do the grunt work of defining 2D and 3D geometry, surface and solid models, and how objects interact. Whether you fillet two lines or Boolean-ize two solids, it’s the kernel performing calculations to come up with a correct result. Kernel vendors also provide advanced technology like collision detection and parametric constraints.
- Complete programs let you sell a CAD program as “your own,” complete with your company’s logo. These are sometimes known as OEMs, named after “original equipment manufacturers” from the automotive world, of which common ones are IntelliCAD, AutoCAD OEM, and ARES. Other vendors provide OEM rendering and analysis programs that run inside the CAD program or link to it externally.
Formats supported by the Open Design Alliance
Open Design Alliance
One such vendor is an oddity: it exists to make no profit. The Open Design Alliance was formed as a non-profit entity in 1998 to promote the use of DWG in non-Autodesk programs. In that, it has been wildly successful, now with 1,200 member companies. In recent years, it branched out to provide APIs that access data in PRC/PDF, MicroStation DGN, IFC [industry foundation class] and Revit, STEP, LandXML, Navisworks, Scan-to-BIM, and so on.
Its annual September conference is a fire hose of information. With covid, the online version of the conference crams what used to be a full day into 1.5 hours. Never mind: what I hear there is what your CAD package might do next year, which makes for interesting listening.
With ODA’s origin in DWG, this meant it first targeted general CAD software. A decade ago, it branched into architectural software by writing APIs for accessing files made by Architectural Desktop, Revit, and the IFC standard. IFC is used to translate architectural drawings between otherwise incompatible programs.
New To the DWG API
New this year is a constraints engine added to the DWG API. It is in beta and will be available to member companies by the end of this year.
Model documentation (which is semi-automatically generating 2D drawing views linked to 3D models) is not new to the API, but what is new is saving drawing views in a format compatible with AutoCAD. This means that AutoCAD can read what, say, a BricsCAD or IntelliCAD generates. To do this, the ODA had to implement some Inventor functions, because that's what AutoCAD does.
This year’s conference showed new functions for Parasolid models, where the ODA’s b-rep module now creates boundary representations from Revit, PRC/PDF, and ACIS data embedded in DWG files. And, Parasolid models can be included in DGN files.
ODA for Mechanical CAD
And now the ODA is going whole-hog into MCAD. President Neil Peterson announced that the organization plans to eventually support all major 3D proprietary formats, like Catia, NX, Solidworks, and Inventor. It already supports 2D AutoCAD Mechanical, 3D Mechanical Desktop, IGES, JT, and STEP files.
The work will begin in January, hopefully. These initiatives take years of programming, usually in the order of first reading files, and then displaying them. ODA has no plans to write proprietary MCAD formats.Not all objects are supported right away, as we see with Revit where more objects are supported each year, never mind keeping up with Autodesk’s changes to the RVT and RFA formats.
But what about formats Autodesk abandoned long ago, such as AutoCAD Architectural and Mechanical? Autodesk may have abandoned them, but drawings haven’t; “millions” still exist and need to be updated from time to time.
One of the unspoken embarrassments of the CAD world is that drawings need to be readable sometimes decades later; yearly software updates are the enemy of permanence. Companies like Boeing treat the problem very seriously; they expect their B-52 bomber, for instance, to have a hundred-year lifespan. Same for builders of ships, processing plants, and nuclear reactors.
As a result, the ODA offers 100-year legacy support for any CAD vendor, and already is the official maintainer of the DGN format on behalf of Bentley Systems. On the list are DWG, Revit, PRC/PDF, and DGN. As well, it works closely with BuildingSmart on developing future releases of IFCs and with PDES on the STEP format. STEP makes sense, because it is the IFC of mechanical drawings, an international standard becoming more capable as it handles more and more aspects of CAD and CAM.
The ODA can make the promise of 100-year-support, because the ODA cannot be acquired and shut down by a hostile firm; only its members can vote to dissolve it, and that is not in their self-interest. “Actually, the goal is to keep the organization going for 100-200 years,” Peterson told me.
How the ODA Works
The ODA funds programming in two ways. Most of it comes from annual fees, which start at $2,400 for for-profit entities and gives member companies access to most of the APIs, ones considered core to the ODA, like DWG, DGN, and PDF.
Then there are other file formats that the ODA doesn’t feel the entire membership would benefit from, and so it allows side projects. The SIG (special interest group) program lets, say, ten companies cooperatively fund and work together on a project. This is how Revit and Navisworks translation got started, and is how the latest SIG, Scan to BIM, got launched. In these cases, if you want access to Revit APIs, you become a member of the SIG, which is an extra $5,000 a year. The new proprietary mechanical format initiative is also being done through a SIG.
What Ralph Grabowski Thinks
I don’t think existing translation firms that handle MCAD formats are quaking in their shoes from the ODA announcement. They have decades experience delving into the mysteries of Catia and other formats, and it will take the ODA a year or more to ship an initial API, with years of updates to follow. That, and the ODA price is not low, ranging from $13,600 to $24,400 annually, depending on the access a SIG member desires, albeit with no royalty payments.
As much as open software advocates would prefer the industry to follow their wishes for freedom from corporate lock-in, “open standards are not displacing proprietary standards; rather they are complimenting each other,” says Mr Peterson. So, users want tools that work with both approaches, which is why the ODA is working towards producing universal viewers and data access for “any engineering format.”
[This article first appeared in Design Engineering magazine and is reprinted with permission.]
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