The Continuing Quest For Neutral Design Data, Part 19 Aug, 2006 By: Jeffrey Rowe
A Brief Look at JT Open
A truly neutral design data format has been the CAD community’s holy grail for quite some time now. Unfortunately, as we all know too well, the quest for this holy grail is still far from being realized. Instead of design data file formats consolidating and becoming more neutral, they seem to proliferate more over time. In the past, several types of organizations -- software vendors, manufacturing companies and standards bodies -- have attempted to develop neutral design data formats with varying degrees of success and acceptance.
While not universally adopted, one of the more successful attempts has been UGS’ JT Open initiative. Since its initial launch in November 2003, it has gained significant industry visibility and represents UGS’ strategy for helping companies leverage multiple technology investments to structure their collaborative product development environment.
Who is JT Open?
JT Open is an initiative driven by a diverse group of organizations that view PLM as a competitive advantage and have adopted the JT data format as a quasi-standard. JT is a common data format that theoretically enables product visualization and information sharing between PLM software applications. The functionality and lightweight nature of JT technology is intended for viewing and sharing product data and interactive images worldwide, in real-time and throughout all phases of the product lifecycle.
Membership in JT Open is available to all interested parties, including end-user corporations, ISVs (independent software vendors), academic institutions and non-profit industry organizations. Some of the initial JT Open members included UGS, General Motors, Ford, Mazda, PTC, Alias and Actify, as well as academic members Brigham Young University and the University of Michigan. In addition, many other companies that derive indirect value from the initiative participate as JT Open advocates, including HP, Intel and SAP.
What is JT Open?
JT Open is not an attempt to create a true standard, such as STEP or IGES -- those formats address different requirements, namely interoperability. JT is a format tailored for multi-CAD data-sharing, based on a high-definition, small footprint as well as optional precise (b-rep) information. There are several important differences between this and other available visualization and representation technologies.
The JT Open Toolkit (used for creating JT-formatted data) is a C++ library and is available for several hardware and operating system platforms, including Windows, SUN, HP, SGI and AIX. Software product development organizations have developed translators from many mechanical CAD systems into JT. It’s usually the only format common to the major applications typically used in an enterprise.
When the JT Open Toolkit exports a model, the toolkit creates one or more DirectModel files, referred to as JT files, with a JT file extension. JT files represent a flexible data format, capable of storing such things as:
- directly renderable geometry,
- analytical geometry,
- geometric attributes,
- user metadata,
- hierarchical CAD product structure and
- CAD PMI (product manufacturing information), GD&T (geometric dimensioning and tolerancing) and FD&T (functional dimensioning and tolerancing)
JT data can be very lightweight, holding little more than facet data, or it can be richer and hold associations to original CAD information, assemblies, product structure, geometry, attributes, meta data and PMI. It also supports multiple tessellations and levels-of-detail.
To help shrink the storage and transmission bandwidth requirements of 3D models, JT files can be compressed. The compression is transparent to a JT data user, and a model can be composed of JT files using different compression settings (including none). The compression form used by a JT file is related to the JT file format version in which it was written.
A Strong Community
Although less than three years old, JT Open has become an influential community of users, software vendors and other parties across the PLM chain who, through an open distribution of the JT technology and its business model, are able to share 3D data. To date, the JT data format has seen its most widespread use in the automobile and aerospace industries, but is equally suitable for all manufacturing industry segments.
According to the JT Open organization, today there are more than 40,000 JT-enabled sites worldwide, representing but a fraction of the potential market. Current industry thinking is that for every 3D CAD seat deployed, 20 to 30 end-users can use the data in the context of visualization and interrogation using less expensive applications on less expensive hardware. A recent estimate of the global 3D CAD installed base of approximately two million legitimate, licensed seats puts the opportunity for JT-enabled applications at more than 40-to-60 million seats. Whether these numbers will ever be realized is debatable, but suffice it to say, the potential is huge.
As stated earlier, JT’s other (actually a continuing) attempt is to be a truly neutral CAD data format for viewing and other purposes that doesn’t require a product or technology from the company from which the data originated. For the mechanical CAD world it’s interesting to see that so many of the major CAD vendors are members of the organization -- especially those that currently develop and market products with proprietary data formats for use with their respective software packages and for communicating that data across the Web to those who may or may not have those software packages.
Although JT seems to have gotten the lion’s share of publicity in the neutral data arena, it’s not the only player. A couple of other neutral data initiatives -- such as Dassault’s 3D XML, the Web 3D Consortium’s X3D and others -- continue to be developed, but seemingly have not attracted the level of interest and/or momentum that JT has. There are a number of reasons for this, and we’ll explore some of the other neutral data formats and the organizations behind them in a future installment. Until then, may the communities that create and use design data continue to search for the holy grail of design data neutrality.