JT (visualization format)
Encyclopedia
JT is a 3D data format developed by Siemens PLM Software (formerly UGS Corp.) and is used for product visualization, collaboration
, and CAD data exchange
. It can contain any combination of approximate (faceted) data, exact boundary representation surfaces (NURBS), Product and Manufacturing Information
(PMI), and Metadata
(textual attributes) either exported from the native CAD system or inserted by a product data management (PDM) system. It is probably the most widely used 3D visualization format for discrete manufacturing with over 4,000,100 JT-enabled licenses of software in use. On 2009 September 18 the ISO stated officially that the JT specification has been accepted for publication as an ISO Publicly Available Specification (PAS).
Because JT files are inherently "lightweight" (~1-10% of the size of a CAD file) they are ideal for internet collaboration. With the growing trend toward globalization, more companies are leveraging resources wherever they are available in the world. Collaboration using JT allows companies to send 3D visualization data to suppliers and partners much more easily than sending the associated "heavy" CAD files. In addition, real-time, on-line collaboration is easier because the amount of information sent back-and-forth across the internet is reduced. Finally, JT provides an inherent security feature such that intellectual property does not have to be shared with inappropriate parties. As indicated above, JT can contain any combination of data such that the right amount of information can be shared without exposing the underlying proprietary design definition information.
JT is often used for Digital mockup
(DMU) work, which allows engineers to validate that a product can be assembled together without interferences long before a physical prototype could be produced. This "spatial validation" is enabled by precise measurements and cross-sectioning as well as sophisticated clearance/interference detection. Leveraging JT for digital mockup allows users to reduce or eliminate costly physical prototypes and enables decision-making to occur much earlier in the development process.
Finally, JT is used as a CAD interoperability format for exchanging design data for Collaborative Product Development
, where JT files are created by translating data from CAD systems such as NX (Unigraphics)
, Creo Elements/Pro, I-DEAS
, Solid Edge
, Catia
, or Autodesk Inventor
. JT is supported by an open industry forum, the JT Open Program, that is an open, influential community of users, software vendors, and interested parties advocating the use of JT as the visualization, collaboration and data-sharing standard for the PLM industry. The JT Open members have also proposed JT as suitable for use as a long-term data archival format.
and Hewlett Packard as the DirectModel toolkit (initially Jupiter). When EAI was purchased by UGS, JT became a part of UGS Corp.’s suite of products. Early in 2007 UGS announced the
publication of the JT data format easing the adoption of JT as a master 3D format. Also in 2007, UGS was acquired by Siemens AG and became Siemens PLM Software. JT is the common interoperability format in use across all of Siemens PLM Software and has been adopted as the long term data archival format across all of Siemens.
(i.e. those containing tens of thousands of components). The JT file format is capable of storing an arbitrary number of faceted representations with varying levels of detail (LODs). When the whole product is displayed on the computer screen the hosting application displays only a simple, coarse, model. However, as the user zooms into a particular area, progressively finer representations are loaded and displayed. Over time, unused representations are unloaded to save memory.
. It also supports multiple tessellations and level-of-detail (LOD) generation.
JT supports common product structure-to-file structure mappings. These include:
Client applications may use these mappings, or choose to define their own custom mapping.
To date, the JT file format has evolved through two forms of compression, exposed in JT Open Toolkit as standard and advanced compression. These differ in that the former employs a simple, lossless compression algorithm, while the latter employs a more sophisticated, domain-specific compression scheme supporting lossy geometry compression. Client applications are encouraged to take advantage of advanced compression over standard compression, as attainable compression ratios are much greater. Support for standard compression is maintained only in the interest of backward compatibility with legacy JT file viewing applications.
The compression form used by a JT file is related to the JT file format version in which it was written. This version is readily viewable by opening a JT file in a text editor and looking at its ASCII header information.
Collaboration
Collaboration is working together to achieve a goal. It is a recursive process where two or more people or organizations work together to realize shared goals, — for example, an intriguing endeavor that is creative in nature—by sharing...
, and CAD data exchange
CAD data exchange
CAD data exchange involves a number of software technologies and methods to translate data from one Computer-aided design system to another CAD file format...
. It can contain any combination of approximate (faceted) data, exact boundary representation surfaces (NURBS), Product and Manufacturing Information
Product Manufacturing Information
Product and manufacturing information, also abbreviated PMI, conveys non-geometric attributes in 3D computer-aided design and Collaborative Product Development systems necessary for manufacturing product components or subsystems. PMI may include geometric dimensions and tolerances, 3D...
(PMI), and Metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
(textual attributes) either exported from the native CAD system or inserted by a product data management (PDM) system. It is probably the most widely used 3D visualization format for discrete manufacturing with over 4,000,100 JT-enabled licenses of software in use. On 2009 September 18 the ISO stated officially that the JT specification has been accepted for publication as an ISO Publicly Available Specification (PAS).
Overview
JT files are used in product lifecycle management (PLM) software programs such as Teamcenter (Lifecycle Visualization), or PTC Windchill and their respective CAD solutions, NX and Creo Elements/Pro by engineers and other professionals that need to analyze the geometry of complex products. The format and associated software is structured so that extremely large numbers of components can be quickly loaded, shaded and manipulated in real-time. Because all major 3D CAD formats are supported, a JT assembly can contain a mixture of any combination which has led to the term "multi-CAD". As JT is typically implemented as an integral part of a PLM solution, the resulting multi-CAD assembly is managed such that changes to the original CAD product definition files can be automatically synchronized with their associated JT files resulting in a multi-CAD assembly that is always up-to-date.Because JT files are inherently "lightweight" (~1-10% of the size of a CAD file) they are ideal for internet collaboration. With the growing trend toward globalization, more companies are leveraging resources wherever they are available in the world. Collaboration using JT allows companies to send 3D visualization data to suppliers and partners much more easily than sending the associated "heavy" CAD files. In addition, real-time, on-line collaboration is easier because the amount of information sent back-and-forth across the internet is reduced. Finally, JT provides an inherent security feature such that intellectual property does not have to be shared with inappropriate parties. As indicated above, JT can contain any combination of data such that the right amount of information can be shared without exposing the underlying proprietary design definition information.
JT is often used for Digital mockup
Digital mockup
Digital MockUp or DMU is a concept that allows the description of a product, usually in 3D, for its entire life cycle. Digital Mockup is enriched by all the activities that contribute to describing the product. The product design engineers, the manufacturing engineers, and the support engineers...
(DMU) work, which allows engineers to validate that a product can be assembled together without interferences long before a physical prototype could be produced. This "spatial validation" is enabled by precise measurements and cross-sectioning as well as sophisticated clearance/interference detection. Leveraging JT for digital mockup allows users to reduce or eliminate costly physical prototypes and enables decision-making to occur much earlier in the development process.
Finally, JT is used as a CAD interoperability format for exchanging design data for Collaborative Product Development
Collaborative Product Development
Collaborative product development is a business strategy, work process and collection of software applications that facilitates different organizations to work together on the development of a product...
, where JT files are created by translating data from CAD systems such as NX (Unigraphics)
NX (Unigraphics)
NX, also known as NX Unigraphics or usually just U-G, is an advanced CAD/CAM/CAE software package developed by Siemens PLM Software.It is used, among other tasks, for:* Design...
, Creo Elements/Pro, I-DEAS
I-DEAS
I-DEAS , a Computer-aided design software package. It was originally produced by Structural Dynamics Research Corporation in 1982. I-DEAS was used primarily in the automotive industry, most notably by Ford Motor Company and by General Motors...
, Solid Edge
Solid Edge
Solid Edge is a 3D CAD parametric feature solid modeling software. It runs on Microsoft Windows and provides solid modeling, assembly modelling and drafting functionality for mechanical engineers...
, Catia
Catia
Catia may refer to*Catia - neighbourhood of Caracas*Catia La Mar - Venezuelan town*Catia - a family in Ancient Rome*Catia - type of butterfly*CATIA...
, or Autodesk Inventor
Autodesk Inventor
Autodesk Inventor, developed by U.S.-based software company Autodesk, is 3D mechanical solid modeling design software for creating 3D digital prototypes used in the design, visualization and simulation of products...
. JT is supported by an open industry forum, the JT Open Program, that is an open, influential community of users, software vendors, and interested parties advocating the use of JT as the visualization, collaboration and data-sharing standard for the PLM industry. The JT Open members have also proposed JT as suitable for use as a long-term data archival format.
History
JT was originally developed by Engineering Animation, Inc.Engineering Animation, Inc.
Engineering Animation, Inc. was a services and software company based in Ames, Iowa , United States. It remained headquartered there from its incorporation in 1990 until it was acquired by Unigraphics Solutions, Inc. in 1999...
and Hewlett Packard as the DirectModel toolkit (initially Jupiter). When EAI was purchased by UGS, JT became a part of UGS Corp.’s suite of products. Early in 2007 UGS announced the
publication of the JT data format easing the adoption of JT as a master 3D format. Also in 2007, UGS was acquired by Siemens AG and became Siemens PLM Software. JT is the common interoperability format in use across all of Siemens PLM Software and has been adopted as the long term data archival format across all of Siemens.
Large Model Rendering
JT was created to support the interactive display of very large assembliesAssembly modelling
Assembly modelling is technology and methods used by computer-aided design and product visualization computer software systems to handle multiple files that represent components within a product. The components within an assembly are represented as solid or surface models.The designer generally has...
(i.e. those containing tens of thousands of components). The JT file format is capable of storing an arbitrary number of faceted representations with varying levels of detail (LODs). When the whole product is displayed on the computer screen the hosting application displays only a simple, coarse, model. However, as the user zooms into a particular area, progressively finer representations are loaded and displayed. Over time, unused representations are unloaded to save memory.
Data Model
The JT data model is capable of representing a wide range of engineering data. This data can be very lightweight, holding little more than facet data or it can be quite rich, containing complete NURBS geometry representations along with product structure, attributes, meta data and PMIProduct Manufacturing Information
Product and manufacturing information, also abbreviated PMI, conveys non-geometric attributes in 3D computer-aided design and Collaborative Product Development systems necessary for manufacturing product components or subsystems. PMI may include geometric dimensions and tolerances, 3D...
. It also supports multiple tessellations and level-of-detail (LOD) generation.
- Product Structure - assembly, part, instance
- Facet - polygon, polygon set
- Lighting - light set, point light, infinite light
- Textures
- Precise Geometry and Topology - point, curve, surface, face, loop, edge, vertex
- Boundary representation (B-rep) could used either JT B-rep or XT B-rep(Parasolid) format.
- Geometry Primitives - boxBoxBox describes a variety of containers and receptacles for permanent use as storage, or for temporary use often for transporting contents. The word derives from the Greek πύξος , "box, boxwood"....
, cylinderCylinder (geometry)A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...
, pyramidPyramidA pyramid is a structure whose outer surfaces are triangular and converge at a single point. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, meaning that a pyramid has at least three triangular surfaces...
, sphereSphereA sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point... - Product Manufacturing InformationProduct Manufacturing InformationProduct and manufacturing information, also abbreviated PMI, conveys non-geometric attributes in 3D computer-aided design and Collaborative Product Development systems necessary for manufacturing product components or subsystems. PMI may include geometric dimensions and tolerances, 3D...
(PMI) - GD&T, 3D annotations - Attributes / Properties - text, integer, float, date, layers
- Meta data - property filters, transforms, bounding box definitions
File Structure
The relationship of product structure hierarchy to exported JT file structure is arbitrary. Any node in the hierarchy may be specified as the start of a new JT file. Thus, product structure may be represented in a variety of JT file configurations.JT supports common product structure-to-file structure mappings. These include:
- Per part - All assembly nodes in a product structure hierarchy are stored in a single JT file, and each part node in the hierarchy is stored in an individual JT file in a subdirectory that is of the same name as the assembly JT file.
- Fully shattered - Each product structure node in the hierarchy is stored in an individual JT file.
- Monolithic - All product structure is stored in a single JT file.
- PLMXML - An open XML-based file format. A PLMXML-structure could link to the model data in another file (an External Representation), or the data can be embedded within the Representation element in the XML file (an InternalRepresentation).
Client applications may use these mappings, or choose to define their own custom mapping.
Compression
To help shrink the storage and transmission bandwidth requirements of 3D models, JT files may take advantage of compression. Use of compression is transparent to the user of the JT data, and a given model may be composed of JT files using different compression settings (including none).To date, the JT file format has evolved through two forms of compression, exposed in JT Open Toolkit as standard and advanced compression. These differ in that the former employs a simple, lossless compression algorithm, while the latter employs a more sophisticated, domain-specific compression scheme supporting lossy geometry compression. Client applications are encouraged to take advantage of advanced compression over standard compression, as attainable compression ratios are much greater. Support for standard compression is maintained only in the interest of backward compatibility with legacy JT file viewing applications.
The compression form used by a JT file is related to the JT file format version in which it was written. This version is readily viewable by opening a JT file in a text editor and looking at its ASCII header information.