Should you use JT or 3D PDF?
I always like a little controversy. Especially when it leads to more understanding.
A few days ago, Dennis Keating, a Senior Account Executive with Siemens PLM, posted this note about JT over on LinkedIn:
Try taking a look at Siemens and the international format for JT. It does not have any of the limitations of 3DPDF and works with all major CAD systems. A large Aerospace & Defense contractor is switching completely from Creo to NX to utilize NX’s PMI and JT and eliminating all 2D drawings. They will use PMI in all downstream applications CAM, CMM, Tooling & Fixturing, and variational analysis & simulation. They benchmarked WF5 & 2 Creo Beta releases and decided to standardize on NX & JT. PTC could not match the functionality and completeness of the NX & JT solutions for thier production environment. They completely eliminated 3DPDF as a solution because of the vast number of deficiencies in the product.
Those sound like good fighting words, don’t they?
Phil Sprier, who sits on the board of directors of the 3D PDF Consortium thought so. Here’s his reply:
Pretty bold and sweeping statements. What specifically are the limitations of 3D PDF that JT doesn’t have? What are the vast number of deficiencies in 3D PDF? Was it really limitations of 3D PDF that caused the unnamed, unconfirmed company to switch to Siemens?
At this point, Jim Merry, who works with Tetra4D (a company that makes 3D PDF authoring software), chimed in:
It is important to distinguish between the capabilities of formats like STEP, JT and 3D PDF and the capabilities of the various tools available to create and consume data in those formats. It’s quite easy to find examples of 3D content creation software that can export high fidelity examples of each as well as low fidelity. The low fidelity examples are not evidence of deficiencies in the formats.
From the end-user point of view, their data would export to one or all of these formats and they could choose the fidelity level to suit their business needs. They could then provide that file to anyone for use within a robust, feature rich, free and ubiquitously deployed application for consuming that data. The view of course is different from the various vendor’s points of view and herein lies the issue/opportunity.
And, to really make things interesting, David Opsahl, the Executive Director of the 3D PDF Consortium, jumped in:
I agree with the above comments. It isn’t enough to put out statements like that without knowing the context – what were the requirements? There are a HUGE number of use cases that JT can’t support because of “deficiencies” it has, which really aren’t deficiencies because JT wasn’t designed to support those things. Similarly there are use cases that JT is suited for that PDF is not. Was this customer attempting to use 3D PDF for things it wasn’t designed to do?
Look, I totally get that we all want to “promote” the products and standards we support. But putting out statements like this, without the backup detail, is irresponsible because you aren’t speaking to the community in a way that allows them to make an informed decision.
I find it extremely curious also that no mention is made of the fact that several of the Manufacturing Engineering products Siemens delivers make use of 3D PDF because of the lack of capability within the JT format. In other words, they are using 3D PDF precisely because JT wasn’t designed to support a large number of use cases. Doesn’t that speak directly to the fact that each has their place – it certainly would seem so.
I couldn’t help but give Davis a hard time (I know him, and he can take it):
David: That’s harsh, dude! Don’t scare Dennis away. I want the backup detail. On both JT and 3D PDF.
Here’s how he replied:
Wasn’t meant to be harsh. I think the point of your comment is the same as we are all saying – details matter. Without the details, its just a self-serving promotional statement. While promotional statements in general are something I’m not fond of, promotional statements that say “this is good” are one thing, but when you say “this is good, and this is bad,” without providing details, I think that crosses a line. The fact that certain Siemens products employ 3DPDF for certain use cases is well known throughout Siemens, so I can only conclude that the purpose of the statement is to scare people away from using 3DPDF and towards JT. The fact is that both have their uses and their intended purposes, and while it is true there may be some overlap, the fact is that overlap, in my view, is very small. If we are going to use communities and social media to inform, we need to exercise responsibility in how we avail ourselves of that right in my opinion.
And Dennis and I used to work together; he knows I’m a pussycat. :-)
He then added this clarification, for anyone reading the thread who might not be familiar with the issues:
I would like to add some additional thoughts for folks who are members of this group, who might be wondering what they should look for when trying to make sense of which formats matter. I can’t speak to Dennis’s intent specifically, but the implication is certainly there that 3DPDF is inferior to JT. Setting aside for the moment any variations in “fit for purpose”, or applicability to use cases, the potential evaluator or user should consider the following.
- One can certainly compare any two (or more) formats for applicability to a certain use case. For instance, I might wish to compare JT to 3DPDF in their ability to accurately represent geometry or product manufacturing information (PMI). In the case of PDF, and 3DPDF in particular, I now have to pick *which* 3D format defintion I wish to use – U3D or PRC, as PDF supports both. At the end of the day, however, this is a comparison of *formats*. That’s all it is – a measure the *potential* of a tool or tools which support the format to solve my particular problem.
- Formats in and of themselves do not accomplish anything, however. What does matter is how has the provider of the products involved *implemented* the format. Does it have the two key attributes – conformance, and quality – necessary to produce a successful outcome? The former is the degree to which a given implementation adheres to the standard as exemplified by the output of the application; the second is a measure of reliability – can it repeatedly produce results that are conforming to the standard? As with anything, the position of products in the market with regards to these two measures will vary. Some will support it well, others less so. It is important to note that the variation in conformance and quality observed in various products is *not* a format issue, but an implementation issue.
- In competitive benchmarks, such as the one outlined above, it is also very true (and has been for many years) that if a standard format is to be used as a means to interchange data between products that all originate from the same developer, that it should be expected they can “tweak” the implementation to a great degree among their own products, and still not necessarily produce data that conforms to the specification. In this case, since Siemens/UG origniated JT, one would expect, and you would probably see, a high degree of conformance. However, as we all know, the world is not a homogeneous platform. It might be within one set of walls (a single company), but that has nothing to do with how well the data exchange or communication will work when it is necessary to work *outside*, with partners, suppliers, or customers. Here again, if everyone in a value chain decides to be homogeneous - AND – they also agree that the limits of which use cases can be accomplished with that set of tools is sufficient, then it *might* work.
- Lastly, one cannot let the limitations of any format (and they ALL have limitations) define the bar of success. The simple fact is that there is no one format (JT, STEP, PLCS, PDF, etc.) that will address the spectrum of critical use cases in an organization. We might wish that were the case, because it would make life simpler, but its simply not going to happen in the foreseeable future.
Overall, I thought it was a rather enlightening conversation. Except—what about the differences between JT and 3D PDF?
I can tell you a few of them: JT is suitable for digital mock-up. 3D PDF isn’t. 3D PDF supports document-centric output, and is consumable by anyone who has Adobe Reader on their computers. JT not so much.
There are a lot more differences, but, really, I think we need to step back, and do a real side-by-side comparison of the two formats (and the tools used to author them), to better understand their strengths and weaknesses. What do you think? Would you be interested in seeing such a comparison?