poka.sh

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JT

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Siemens JT.

At a glance
Original creator Engineering Animation, Inc. and Hewlett-Packard, as the Jupiter / DirectModel toolkit; later UGS, then Siemens
Purpose A lightweight 3D product-definition format used for visualisation, communication and digital mock-ups in product lifecycle management.
Extensions .jt
Poka parser poka-jt
Viewer poka-3d-viewer
Depth tier Parser with a shared viewer (see Depth tiers)
Breadth tier B3 Core (see Breadth tiers)

How much Poka reads

B3 Core. Only the main content type or types are decoded (for example geometry but not materials, layers or annotations, or only one version family). The list of gaps is substantial.

Confidence: medium (the reviewer read the code). Basis: Reviewed 2026-10-16: poka-jt (main.rs, v8.rs, v9.rs, topo.rs, codec.rs), its own decoder; 82 tests pass (1 skipped) including full-area checks on the three corpus files (Cylinder_1_123_100_0_Parts.jt version 8.0, CoffeeMaker.jt 9.5, example_block_jt10.3.jt 10.3), one file per version. Other point releases have no corpus file. Confidence is high for those three versions and low beyond. The assembled appearance of CoffeeMaker.jt was not checked visually.

What Poka does not read

  • The assembly structure and placement: the scene-graph segment is decompressed but only its first element header is read and there is no transform handling, so assemblies are likely drawn in part coordinates rather than assembled (judgement, not rendered)
  • Colours and materials; v8 shapes with texture or colour bindings are refused
  • Geometry kinds other than Tri-Strip Set shapes (found by GUID; not checked whether any corpus file holds other kinds)
  • Lower levels of detail (only the highest tier is drawn), PMI, properties and part names
  • Normals are decoded for v8 only
  • Unknown codecs are errors, not guesses
  • JT 8.1: its test file is not in the corpus, so that test skips

Background

The Library of Congress record says Siemens AG acquired the format in 2007 and that the specification was accepted as an ISO Publicly Available Specification on 18 September 2009, published as ISO 14306:2012 (based on JT 9.5) and replaced by ISO 14306:2017. It gives no first-publication year, so none is stated here. Poka decodes the triangle-strip shape geometry of JT 8, 9 and 10 files, not the whole product structure.

Versions

Version Identifier Poka Note
JT 8.x Version 8.x Read Shape geometry decodes (poka-jt/src/v8.rs), including the lossless-vertex variant. The corpus evidence is a JT 8.0 cylinder file; the JT 8.1 box test skips because its file is not in the corpus.
JT 9.x Version 9.x Read Topologically compressed shapes decode (poka-jt/src/v9.rs, topo.rs); the ISO 14306:2012 edition is based on JT 9.5.
JT 10.x Version 10.x Read Shape geometry decodes; the table of contents uses a wider entry from version 10 (poka-jt/src/main.rs).

Libraries

Libraries Poka uses or has assessed for this format, with the status, licence and language the registry records.

Software that uses it

  • Siemens JT

Sources