标准编号：ISO/PAS 14306:2011
中文名称：工业自动化系统与集成 用于3D可视化的JT文件格式规范
英文名称：Industrial automation systems and integration — JT file format specification for 3D visualization
发布日期：2011-12
标准范围
This Publicly Available Specification defines the syntax and semantics of the JT Version 8.1 file format.The JT format is an industry focused, high-performance, lightweight, flexible file format for capturing and repurposing 3D Product Definition data that enables collaboration, validation and visualization throughout the extended enterprise. JT format is the de-facto standard 3D Visualization format in the automotive industry, and the single most dominant 3D visualization format in Aerospace, Heavy Equipment and other mechanical CAD domains.The JT format is both robust, and streamable, and contains best-in-class compression for compact and efficient representation. The JT format was designed to be easily integrated into enterprise translation solutions, producing a single set of 3D digital assets that support a full range of downstream processes from lightweight web-based viewing to full product digital mockups.At its core the JT format is a scene graph with CAD specific node and attributes support. Facet information (triangles), is stored with sophisticated geometry compression techniques. Visual attributes such as lights, textures, materials and shaders (Cg and OGLSL) are supported. Product and Manufacturing Information (PMI), Precise Part definitions (B-Rep) and Metadata as well as a variety of representation configurations are supported by the format. The JT format is also structured to enable support for various delivery methods including asynchronous streaming of content.Some of the highlights of the JT format include:--Built-in support for assemblies, sub-assemblies and part constructs--Flexible partitioning scheme, supporting single or multiple files--B-Rep, including integrated support for industry standard Parasolid(R) (XT) format--Product Manufacturing Information in support of paperless manufacturing initiatives--Precise and imprecise wireframe--Discrete purpose-built Levels of Detail--Wire harness information--Triangle sets, Polygon sets, Point sets, Line sets and Implicit Primitive sets (cylinder, cone, sphere, etc…)--Full array of visual attributes: Materials, Textures, Lights, Shaders--Hierarchical Bounding Box and Bounding Spheres--Advanced data compression that allows producers of JT files to fine tune the trade off between compression ratio and fidelity of the data.Beyond the data contents description of the JT Format, the overall physical structure/organization of the format is also designed to support operations such as:--Offline optimizations of the data contents--File granularity and flexibility optimized to meet the needs of Enterprise Data Translation Solutions--Asynchronous streaming of content--Viewing optimizations such as view frustum and occlusion culling and fixed-framerate display modes.--Layers, and Layer Filters.Along with the pure syntactical definition of the JT Format, there is also series of conventions which although not required to have a reference compliant JT file, have become commonplace within JT format translators. These conventions have been documented in the “Best Practices” section of this JT format reference.This JT format reference does not specifically address implementation of, nor define, a run-time architecture for viewing and/or processing JT data. This is because although the JT format is closely aligned with a run-time data representation for fast and efficient loading/unloading of data, no interaction behavior is defined within the format itself, either in the form of specific viewer controls, viewport information, animation behavior or other event-based interactivity. This exclusion of interaction behavior from the JT format makes the format more easily reusable for dissimilar application interoperation and also facilitates incremental update, without losing downstream authored data, as the original CAD asset revises.
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