Conducted by Ralph Grabowski and Randall Newton
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| At the end of the Open Design Alliance Conference 2016 in Prague, CAD journalists Ralph Grabowski and Randall Newton spent an hour in a wide-ranging interview with ODA president Neil Peterson about Teigha BIM, versioning control, Autodesk, and PDF. Here is my transcript of the interview.
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About Teigha BIM
Q: How will an independent source for Revit ripple through the industry?
A: It is an untapped market, and so Teigha BIM provides opportunity for everyone. Autodesk did license their API for accessing DWG files, but only to a limited number of firms; we made DWG available to everyone.
With Revit, there is nothing and so there is a hole in the market. Customers who want to streamline their workflow, cannot. Nor is there interoperability for those folks wanting to do competitive products. Teigha BIM is also important to those who want to access their data in years to come, and not be locked down. I've received a lot of interest from people who were not willing to fund the development, but wanted it once it was ready.
Q: Who are these people?
A: We are seeing interest from ODA members, as well as companies who currently are non-members because they hadn't needed access to DWG files.
ODA members and programmers at the annual conference in Prague
Q: Will this kill off IFC?
A: It is too early to say what the fate of IFC is. [BuildingSmart's industry foundation classes were originally developed by Autodesk for exchanging custom entities stored in DWG files; today, it is primarily used to exchange BIM data between programs.]We already have a lot of demand for integrating IFC with Teigha BIM. People are not looking for a replacement for IFC, but as a supplement. Replacing IFC is not in our strategic plans.
Q: Can you describe the development process?
A: This is customer-driven, after some members expressed an interest in accessing Revit data. Teigha BIM began with a small set of members, who are funding the work; the ODA is only coordinating the work. The planning work began in 2013, and then development began in January 2014. We plan to ship Teigha BIM to a wider audience in January. The initial release is already available to the original members who are funding the work.
Q: How will companies use Teigha BIM?
A: They want to process Revit data for other purposes. Most want to import Revit files, and then display the models. Others want to export from their programs to the Revit format.
Import, export (early steps), and rendering (some progress) is what we are working on right now. It is a challenging task working with the complex object model to programmatically create parametric entities in the Revit database.
Q: If I am an HVAC guy, I want to make it a piece of cake to pop my ducting into Revit models.
A: We are currently able to write a small subset of objects into a Revit file. We are a long ways away from doing the full set of entities, like, say, putting in structural engineering.
Q: How much is up to the ODA, and how much is up to third-party developers to be able to write any kind of entity to a Revit file?
A: It is all up to us. We want to make sure that the data written to the file is valid. There is a lot of work on our side to create the APIs, and not much on the member side.
Q: It is my assumption that Autodesk is working on a Web version of Revit, just like Fusion is the "Web version" of Inventor. Would this affect you?
A: We want to provide a toolset that is flexible enough to work on the desktop and the cloud.
Q: One of the reasons for ODA and its predecessors was how fast DWG became ubiquitous. Can Revit become ubiquitous? Except that it isn't in some parts of the world: AllPlan dominates in Germany and Vectorworks is huge in Japan.
A: Revit is dominant in USA and a few other countries, but not everywhere. It is nevertheless important enough that members came forward to put up the money for the development of Teigha BIM.
 Neil Peterson addressing the ODA conferenceAbout Versioning Control
Q: Tell us about the versioning control you announced for DWG files.
A: I was surprised how interested our members are in version control. Everyone I talked to after the presentation at the conference yesterday said they would use it.
Q: It sounded to me like your versioning system makes use of AutoCAD's undo mechanism?
A: It is a modified version of Undo that makes the undo record persistent. Right now it is stored locally in a separate file, but it could also be stored in a central database, as it’s just data.
Q: How does multi-user editing work?
A: It allows multiple users to commit changes to the same file. Once we figured out versioning, then it became much easier to implement multi-user editing for DWG files. Versioning lets us use a standard method to resolve conflicts. We figured out the difficult part: how to manage the deltas [changes] in DWG files through persistent undo transactions. It also solves the problem of transmitting drawing changes over a network, making it efficient to edit files in a client-server architecture [a.k.a. the "cloud"].
Q: Where is Autodesk at with this?
A: To the best of my knowledge, this is new technology. I don't think Autodesk has anything like this. It is a basic tool that has been missing from the market.
About Autodesk
Q: Any reaction from Autodesk to Teigha BIM?
A: No official word. [See the official statement from Autodesk in the previous issue of upFront.eZine; in brief, Autodesk does not object but will not support ODA.]
Q: After the ODA became a significant alternative to accessing DWG files, Autodesk added a source flag to DWG files, warning when a drawing had been saved in a non-Autodesk program. Is there a secret "This is an Autodesk file" flag in RVT files?
A: No, not that we have seen. Although [Autodesk could add one, as] the Revit format is quite fluid; it sometimes changes every six months.
Q: Bricsys and Graebert are extending DWG with unique functions in their AutoCAD-compatible programs, like capabilities for sheet metal and BIM designs. Should the ODA repackage DWG in a new format to accommodate these additions, perhaps with a different extension?
A: There have been discussions internally about a new DWG format, but I believe it is too early for us to do something like that. We see that Autodesk is making fewer and fewer changes to DWG in recent years. If they keep backing off from making those changes, this might provide the opportunity. Once Autodesk freezes it, then we could extend it without affecting compatibility.
It would be an open standard format that everyone could use, but it would not accomplish anything if people don't use it. I think the format needs first to become more mature. In any case, a lot of unique data can be stored in DWG files as it is a very flexible format.
Q: Autodesk at one time said it would change the DWG format every three years, but has not changed it for five years, and in that time has added little to it. Why is Autodesk putting less into DWG?
A: I have no insight into their internal decision-making process.
Q: If several members came to you and asked for an open version of FBX[owned by Autodesk and used in the animation and gaming industries for digital content interoperability], you would--
A: --we don't have an interest in FBX, or even the time to work on it.
Q: What does your new Teigha Mechanical API do?
A: It supports custom entities found in AutoCAD Mechanical.
In this diagram, "Custom" is a placeholder for the RVT/RFA format
About PDF
Q: You are putting a lot of work into PDF import and export. Do people extract data from PDFs?
A: Very little. PDF is mainly for output, by people looking for a high-quality printing solution. We are putting our programming effort into outputting PDFs with small file size and good fidelity by using as many entities native to PDF as possible.
Q: Do you have an import API for bringing PDFs into DWGs?
A: We recommend that people work with Visual Integrity [http://visual-integrity.com], as they specialize in importing PDFs to CAD. We have had a relationship with them for more than five years now.
Q: You are not interested in doing PDF import yourself?
A: The PDF format is complex, and besides there is not much demand for it from our members, so we are happy to leave it to another developer.
Future Plans
Q: I don't think I heard the word "mobile" during the conference.
A: We had nothing new to announce. Anything that can be done on the desktop using our APIs can be done on mobile. We support Android and iOS, and our cloud services make it possible to work with drawings in the Web browser on mobile devices.
Q: What are your plans for the future?
A: Our focus for the next year is to get the things we previewed yesterday [at the ODA conference] into production quality. We have 54 programmers working on our projects. Our Revit support is several years away from being complete. We hope in five years to be at the same level as we are with DWG.
Q: Is there any other CAD platform that you might treat like Revit, such as Onshape?
A: We are not looking into anything else. Onshape is a good member off whom we bounce ideas.
http://www.opendesign.com
[Disclosure: ODA paid for my air fare, hotel accommodation in Prague, and provided some meals.]
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I'm not too fond of funding Kickstarter and Indiegogo projects, because the risk of non-delivery is not worth it. (Exception: I paid $40 for the new Oblivion game, waited two years, and received it. But then I trusted the guys who had made Myst.)
Nevertheless, in the rush to make VR [virtual reality] viable, Stimuli VR is looking for crowdfunding for their minimalist smartphone-holder virtual reality goggles that look like eye glasses -- for $35. As of today, the project is overfunded by 248%, with the 2VR glasses scheduled to ship in November (about two months late at this point). The claim-to-fame is that you can fold up the glasses and put' em in your pocket -- unlike all other VR goggles.
More at https://www.indiegogo.com/projects/2vr-the-vr-headset-for-everyone
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Re: ODA Opens the Revit File Format
What about the precision problems? DWG is much more accurate than RVT. Also the design extents mismatch.
- Dwy Seah via WorldCAD Access
The editor replies: What the ODA is doing is a way to read and write Revit files. It is not a translator to and from DWG. OTOH, PDF is not particularly accurate either, but it seems to work well enough in the CAD world.
Mr Seah responds: Interesting. So, the Revit file will exist in the DWG editor built using Teigha tools will be edited by the DWG editing tools and NOT translate the Revit file into DWG format? If so, this seems a bit unwieldy. Most users would convert the Revit file once and either x-ref the Revit file in DWG format (to avoid having to wait for the conversion every time) or convert and edit the Revit elements in DWG.
PDF is a good comparison. You would only use PDFs as a graphic background. Apparently it is only single precision. It is not used as a primary source of information. Apparently, Revit won't display lines shorter than 1/32in. I suppose this is not a problem for a Teigha user in a DWG environment, but what happens when he saves to Revit format? All those fine screw threads would disappear? Or would the DWG info be preserved in Revit file for later use? It would be interesting to see how this is handled.
The editor replies: It is up to ODA members to decide what they want to use the new Teigha BIM API (aka Revit API) for. So far, the ODA has heard that they want to use it to run external programs that make use of the data stored in Revit files. Right now, these programs have to run inside Revit, which requires a Revit license.
Doing drawing translation between DWG and RVT is a possibility but not the #1 use-case.
This sounds very much like Bentley's Distributed dgn / Design History / ISM technology. What would be good is to know what the impact of this functionality would be on file size and whether the non-graphic attribute data is also tracked. The non-graphic data is in many ways more important, because it i often input parameters that drive the geometric elements and are more difficult to track when modified.
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Amazing news from Ralph Grabowski.
- Rachel Levy via Linked-In
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I hate Autodesk as much as the next poor user, but these ODA guys are just hackers, right? Help me to understand the difference between ODA’s hacking and cracking, and that same activity conducted by the Russian mafia, if you have a moment.
From the perspective of common sense (the only variety I can afford), Autodesk’s ownership of the RVT and DWG file formats is simply a trade secret, like Kentucky Fried Chicken’s secret blend of spices. Using reverse engineering or industrial espionage to discover that trade secret, and then using that trade secret to imitate the product, for any type of gain, is criminal activity, right?
Why should we approve of the ODA, and not the Chinese military, when hacking into and copying Western creativity? Thanks as always for your diligent reporting
- Peter Lawton
The editor replies: The courts have maintained that third-parties have the legal right to interface with hardware and software. Software vendors reacted in two ways:
- Make their file formats public, like Microsoft and Adobe did
- Make their file format complex so that it cannot be reverse-engineered easily, as Autodesk and Dassault Systemes do
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When looking at the new extensions to DWG [such as those created by Bricsys for BIM and MCAD], I believe it is time that the ODA create a new file format, which can take the old DWG data without compression or encryption, and includes the new extensions
- Name withheld by request
The editor replies: The ODA tells me that it is too soon to consider a replacement file format for DWG.
The writer responds: It doesn't have to be a replacement, but an addition. Then the market can make up its mind. This would allow ODA members to add value; ".tga" looks as a good name for an extension.
The editor responds: I think it will become necessary as Bricsys and others cram more into DWG, with some of the info already falling into external support files. The new DWG could be an extensible format like XML or encapsulated format as Bentley did with DGN. THe problem with the .tga extension is that it is used by Targa files.
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