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ISO JT ed2 ISO JT ed2

Table of content

The objectives of this web page is to provide an overview of the status of the standardization of the JT format:

  • Short history of JT (“Jupiter Tessellation”)
  • JT principles: a container of different segments optimized for 3D visualization
  • Summary of CAD kernels of the main CAD systems and role of XT BREP in JT
  • ISO 14306 PAS (“Publicly Available Specification”) 
  • ISO 14306 JT edition 1
  • ISO 14306 JT edition 2 project
  • New CD (“Committee Draft”) ballot for ISO 14306 edition 2 and ASD SSG ballot recommendations for current Committee Internal Ballot (CIB)

Short history of JT (“Jupiter Tessellation”)

JT was created by Engineering Animation Inc (EAI) and Hewlett Packard at the end of the 90ies to enable the visualization of very large mock ups, represented with several Levels Of Details (LODs).  Progressively, it was completed  with other segments, such as the JT BREP segment , 3D exact representation format part of I-DEAS CAD system, then with the XT BREP segment, 3D exact representation format based on Parasolid mathematical kernel, used in several CAD systems, such as NX, SolidEdge, etc. 

The evolutions of JT versions (e.g., V10 and following) are discussed in the JT Open organization, hosted by Siemens PLM.

For more information: www.plm.automation.siemens.com/en_us/products/open/jtopen/

JT principles: a container of different data segments optimized for 3D visualization. JT can be summed up as a file format containing different segments, optimized for 3D visualization by specific processing of each segments according to the users needs.

There are different segments according to:

  • The types of CAD information: Product and Manufacturing Information, meta data, 3D wireframe representation, 3D exact representation (JT BREP, XT BREP), 3D curved tessellated representation (ULP),
  • The levels of representations of 3D tessellated geometry (LODs).

ISO 14306 PAS (“Publicly Available Specification”)

Based on the list of requirements published by ISO in 2008 to select ISO standards for 3D visualization, Siemens PLM has proposed JT V8.1 which was accepted as ISO/PAS 14306 by ISO /TC 184 /SC 4 in December 2011.

ISO 14306 JT Edition 1

Note: the “ISO JT Edition 1” here refers to ISO 14306:2012 Industrial automation systems and integration -- JT file format specification for 3D visualisation.

Siemens PLM has proposed JT to become an ISO standard. A Draft International Ballot (DIS) was organized in 2012, which has failed, XT Brep technology being not considered as sufficiently open for ISO standardization. An agreement at the international level has been voted with unanimity to allow the publication of ISO 14306 in Dec. 2012 ( Link ) with  the following decisions:

  1. Publication of ISO 14306 edition 1, with limitations on the initial scope (note N1), and the publication of the XT BREP segment as a “non normative” (“informative”) annex of the ISO 14306 standard for legacy purpose.
  2. To submit a New Work Item (NWI) for ISO 14306 edition 2, with the replacement of the XT Brep and JT Brep segments by a normative STEP 3D Brep segment.

Note N1: Extract from ISO 14306:2012, page 1: “The following are outside the scope of this International Standard:

— long term data retention;
— non-faceted geometric data exchange.”

So ISO JT Edition 1 is a normative standard dedicated to 3D visualization, with limitations in terms of both scope (exact geometry is excluded) and usage (data archiving and 3D exact geometry data exchange are excluded).

Summary of CAD kernels of the main CAD systems and role of XT BREP in JT

The next figure represents the main CAD systems and their associated CAD kernels (library of mathematical algorithms and Application Programming Interfaces).

XT BREP is the native format of the Parasolid CAD kernel, owned by Siemens PLM solutions, and used in several CAD or visualization applications, such as NX, SolidEdge.

 

The ASD SSG considers that XT BREP model is not fully open; it is part of the Parasolid kernel, whose information model is not fully published and its evolutions are managed by Siemens PLM.  Therefore, data exchange based on XTBREP information model will penalize the companies using CAD systems not based on Parasolid CAD kernel.

ISO 14306 (JT) edition 2 project

As requested by the SC4 resolution in June 2012, the following NWI has been proposed to ISO with YES vote from all involved national bodies:
"This project will enhance the ISO 14306 (JTed1.0) with an edition 2 (JTed2.0) by replacing the JT Brep, XT Brep geometrical containers by their STEP Part 42 equivalent components and will add STEP AP242 external element references addressing mechanism. Performance, file size and related aspects will be taken carefully into account.
The following capabilities will be added to the format described in ISO 14306:
      Part 42 geometry definitions;
      STEP AP242 external element references;
                              
The following ISO 14306 existing capabilities will be deprecated and removed: XT Brep segments, JT Brep segments.
The ULP and LWPA segment will be compared to the new Part 42 container and revised if needed.
In order to provide JTed2.0 as fast as possible to the market, additional requirements would be processed through further JTed2.x versions. "

Failure of first CD ballot of ISO 14303 JT edition 2

After the JTed.2.0 project start, a group of automotive stakeholders represented by the Global Automotive Action Group (GAAG) and ProSTEP iViP have raised a series of comments against the deprecation of the XT B-Rep Segment in JTed2.0. Consensus has been reached in 2013 with the automotive representatives to keep the description of the XT B-Rep segment in the document as an informative annex. 

JT Segments as per ISO14306 edition2 first CD ballot, May 2014

A Committee Draft document  (CD) was produced taking into account the various comments raised during the discussions that took place in 2013, and submitted to the ISO for Ballot in May 2014.

This first CD Ballot failed due to the conjunction of 2 NO votes against the presence of XT-Brep in the document , 2 NO votes against the replacement of XT-Brep by STEP and 1 NO vote due to lack of consensus.

New CD (“Committee Draft”) ballot for ISO 14306 JT edition 2

The comment resolution of the first CD ballot took 9 months from August 2014 to April 2015.

A new CD Document is under final edition and the question of the status of XT Brep segment in ISO 14306 was once again raised by the GAAG and ProSTEP iViP, without final consensus.

This question to have XT BREP segment normative in ISO 14306 has already been raised several times between 2012 and 2015 with a systematic negative answer.

During the last ISO /TC 184 /SC4 meeting in April 2015 it has been decided that this question will be asked again for the last time to the ISO national bodies. A Committee Internal Ballot (CIB) is on going for an answer before July 4th, 2015 on the following 2 questions:

Question:  The XTBrep geometric container of JT should be:

  1. Removed and replaced as per the original work item
  2. Retained as an informative segment, as per the first edition and first CD
  3. Retained as a normative segment
  4. No opinion.

Question:  The scope statement for JT edition 2 should:

  1. Continue to exclude exact geometry exchange and long term archiving, as for edition 1 and the CD document
  2. Remove the constraint, so that the scope is expanded to include exact geometry exchange and long term archiving
  3. No opinion"

[Full questions available here].

ASD SSG position statement

The ASD SSG consider that the ISO Resolution I & J of the ISO TC 184/SC 4 meeting of June 2012 and the NWI for ISO 14306 edition2 have been agreed at international level by national bodies, and shall be applied in order to ensure interoperability and vendor’s independence for ISO JT file format specification for 3D product data visualisation.

The ASD SSG has recommended the following answers to the 2 questions:

  • Question:  The XTBrep geometric container of JT should be:
    Retained as an informative segment, as per the first edition and first CD.
  • Question:  The scope statement for JT edition 2 should:
    Continue to exclude exact geometry exchange and long term archiving, as for edition 1 and the CD document.

Results of the ballot

The results of the ISO/TC 184/SC 4 internal committee ballot on the status of XT B-Rep and the scope restrictions are that XT B-Rep shall stay an informative annex and the scope restriction shall stay in the Committee Draft.

The ASD SSG is confident that this result will lead to a Committee Draft aligned with the ASD SSG requirements for JT edition 2.  European Aerospace and Defence Industry confirms the need to have a visualisation standard compatible with the STEP environment.

Result of the CD Ballot October 2015

ISO 14306 edition 2 committee draft (ISO-JTed2) has past the CD ballot with 13 "Yes", 1 "No" and 3 abstentions.
We are glad of the large consensus to proceed ISO-JTed2 as a draft international standard.
After 2 years of reducing the gaps in the documentation, the document is now in a state suitable for an ISO publication.
The DIS publication of ISO-JTed2 based on the sucessfull CD document is scheduled for march 2016.