JT Import-Export Component


The Open CASCADE JT Import-Export SDK provides Open CASCADE Technology-based applications with the capability to:
  • read a JT file into a JT model;
  • write a JT model into a JT file;
  • create, explore and modify JT models.
Based on this SDK, it is possible to implement powerful JT visualization functionality using LOD management, object’s culling and multi-threaded processing of parts (integration in customers’ applications is available as additional service). The following kinds of data can be stored in a JT model provided by this SDK:
  • assembly tree;
  • mesh representation (triangulation) at different Levels Of Detail (LOD) of the whole JT model and its parts;
  • names, colors and transparency of JT parts.
The Open CASCADE JT Import-Export SDK also provides:
  • Late Loading mechanism to delay loading of the data associated with parts of the JT model until they are actually needed;
  • data compression by JT standard compression algorithms.
The Open CASCADE JT Import-Export SDK provides converters:
  • from an OCAF (Open CASCADE Application Framework) document to a JT model, to transfer the hierarchy of names, colors and meshes of the OCAF document to the JT models;
  • from a JT model to an OCAF document, to transfer the hierarchy of names, colors and meshes of the JT model to the OCAF document.
The first converter is especially useful when data from other widely used CAD formats (such as STEP, IGES, DXF, ACIS, Parasolid and other native formats) read by the corresponding interfaces need to be converted to JT format. This SDK contains examples (Draw commands) of using these converters.


  • Reading of JT format versions 8.1, 9.5 and 10.0;
  • Writing in JT format version 8.1.
This SDK supports the following capabilities of JT format:
  • LOD by elements “Vertex”, “Tri-Strip Set” and “Primitive Set”;
  • attributes “Geometric Transform” and “Material”;
  • properties “Late Loaded” and “String”;
  • all node elements except for “Switch”;
  • “Data Compression and Encoding” by all “Encoding Algorithms”, compressions “ZLIB” and “LZMA”.


  • Faster data reading and reduced size of written data thanks to parallel processing.
  • Data conversion between different versions of JT format.
  • Full access to supported JT structures.
  • Convenience and flexibility of exchanging JT data with OCAF documents.
  • No third-party license required.
  • Source code can be licensed.


The JT SDK is based on the latest version of Open CASCADE Technology, and requires no other external software. It is available on all platforms supported by the corresponding version of Open CASCADE Technology. Operational mode and possible limitations are described in the documentation accompanying the module.
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