How to convert glTF
to JT?

glTF is an open standard file format for 3D scenes and models. It's designed to be compact and efficient, making it easy to distribute and render 3D content on various platforms and devices.

glTF files contain information about the 3D scene, including geometry, materials, animations, and more. They can be used in different applications, from gaming and virtual reality to augmented reality and web-based 3D experiences.

Support of glTF in CAD Exchanger

CAD Exchanger can import and export glTF 2.0 files in binary (.glb) and text (.gltf) format. Such support includes:

• polygonal representations;
• assembly structure;
• names;
• colors, materials, textures;
• user-defined properties;
• PMI as polylines (export only).

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Pros of the format

Efficiency

All the basic data (vertices, triangles, normals, UV coordinates, etc.) are contained in binary form and can also be further compressed. Besides, the file structure is carefully organized to ensure that there is no extra or redundant data. Thus, the file contains only the necessary information to define the 3D scene, without any unnecessary clutter. By eliminating redundant data, glTF files become more lightweight and easier to process.

Cross-Platform Compatibility

It is an open standard supported by a wide range of platforms and applications. This allows for seamless integration between different software, making it easier to share and view 3D models across various devices. Whether it's a web browser, a virtual reality headset, or a mobile device, glTF ensures that your 3D content can be experienced on different platforms without any compatibility issues.

Cons of the format

Lack of Backward Compatibility

glTF has seen rapid development and improvements over the years, which means that older versions may not be fully compatible with newer software or engines. This can be a challenge if you are working with older files and need to use them in a newer environment.

Limited support of advanced features

For more advanced usage scenarios it may be important that this format has limitations in the areas of animation and lighting. In particular, there is inadequate support for keyframe animation with cubic interpolation, animation of rotation angles, and tension-continuity-bias animation curves. glTF also doesn't support lights and multiple attenuation models.

FAQ

What are the glTF file extensions?

glTF files typically have the extension ".gltf" or ".glb". The ".gltf" extension is used for the textual representation of the glTF file format. It is a human-readable JSON file that contains all the necessary information to define the 3D scene structure, including geometry, materials, animations, and more.

The ".glb" extension represents the binary version of the glTF format. It is a binary file that contains all the data, including the scene hierarchy, geometry, textures, and more, in a compact and optimized manner.

How to open an .glTF file?

To open this file, you will need a compatible software application, for example, CAD Exchanger Lab. Launch the software and navigate to the 'New file' option. Browse your computer's directories and locate the .gltf file you want to open. Then select it and click "Open". Once the import process is complete, the .obj file should be loaded into the software, allowing you to view and interact with the 3D model and associated data.

History of glTF format

This format was initially introduced by Khronos Group in 2015. The initiative aimed to create a common, royalty-free specification for efficient transmission of 3D content, with a focus on real-time applications and web delivery.

The first version, glTF 1.0, was released in 2015, providing a foundation for 3D asset transmission. Building upon the success of glTF 1.0, the Khronos Group released glTF 2.0 in 2017, which brought significant improvements and expanded capabilities. glTF 2.0 introduced a more efficient binary file format, enhanced support for physically-based materials, skeletal animations, and more advanced rendering features. It also introduced a clear separation between the JSON scene description and binary data, allowing for more efficient transmission and loading.

Since then, glTF has gained widespread adoption and support across the industry. Numerous software tools, engines, and platforms have embraced glTF as a standard for delivering 3D content. The format continues to evolve with regular updates and extensions, addressing new requirements and advancing the state of 3D content transmission.

The JT format is a widely used lightweight 3D data format designed for efficient visualization, collaboration, and sharing of complex 3D models and assemblies. JT files retain the fidelity of the original 3D models while minimizing file size, enabling fast loading and efficient data transmission. The format supports features like precise geometry, polygonal meshes, product structure, PMI, and animations.

Support of JT in CAD Exchanger

CAD Exchanger can import files compliant with the JT formats from 8.0 to 10.5 and ISO14306:2012 and export files compliant with the JT formats 9.5 and ISO14306:2012. Such support includes:

• B-Rep representations;
• polygonal representations (incl. multi-LODs);
• assembly structure, including via external files;
• names;
• user-defined and validation properties;
• PMI;
• colors, materials, textures;
• layers.

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Pros of the format

Advanced compression and economical data representations

Advanced compression and economical data representations

This file format employs advanced compression techniques to reduce file sizes without compromising the quality of the content. This enables efficient transmission and storage of 3D models and other visual data.

In addition to compression, JT excels in economical data representations. The format is structured in such a way that it is relatively easy to read in a selective manner. Files typically have smaller file sizes than STEP files with comparable geometry. This is achieved by efficiently representing mesh data through topological compression algorithms, which take advantage of the connectedness between mesh patches. Despite the economical representation, JT files maintain their integrity and provide a comprehensive visualization of the original content.

Great meshes support

The format is designed to handle complex 3D mesh data efficiently, making it ideal for applications that require high-quality mesh representation. JT allows for the precise encoding of mesh data, including vertex positions, normals, texture coordinates, and more. It supports both triangular and polygonal meshes, enabling the representation of intricate geometric shapes with smooth surfaces.

Moreover, JT provides robust support for mesh attributes and properties. This means that additional information, such as material properties, colors, and transparency, can be associated with individual mesh elements or the entire mesh.

Cons of the format

Proprietary legacy

While the ISO standardization brought greater openness and interoperability to this format, the legacy of its proprietary history can still be observed in certain cases. It's worth noting that the specifications for JT 7.x and earlier versions were not publicly accessible, and the format was essentially proprietary, so there were difficulties in reading and writing this format in other CAD software. Fortunately, these versions of files are not used much these days.

Implementing full-fledged JT support can be a demanding task. It requires a deep understanding of the intricacies of the format's specifications and algorithms. This can be a barrier for smaller software developers or independent implementers who may not have the resources or expertise to fully grasp and implement the complexities of the format. As a result, the quality of JT support can vary significantly.

Another consequence of the proprietary nature of the JT format is its lack of openness. The latest JT precise geometry representation is based upon the Siemens PARASOLID, which means a high-quality implementation of the format must also be able to read and write this format.

FAQ

Is JT format specification publicly available?

Yes, it is. The JT Open Program, an industry consortium dedicated to promoting the widespread use of JT as a 3D data format, provides the JT file format specification to the public. It offers various resources, including technical documentation, whitepapers, and specifications related to the JT format. These resources can be accessed on the official JT Open Program website.

What are JT file extensions?

The JT format typically uses the file extension ".jt" to denote JT files. It is worth noting that alternative file extensions may also be used in certain cases, depending on the software or system. However, ".jt" remains the most commonly used and recognized extension for JT files across different platforms and applications.

How to open a JT file?

To open this file, you will need a compatible software application, for example, CAD Exchanger Lab. Launch the software and navigate to the 'New file' option. Browse your computer's directories and locate the .jt file you want to open. Then select it and click "Open". Once the import process is complete, the .obj file should be loaded into the software, allowing you to view and interact with the 3D model and associated data.

History of JT format

The JT format, also known as Jupiter Tessellation, has a long history that traces its origins back to the 1990s. It was developed by Engineering Animation Inc., a company specializing in computer graphics and visualization software. EAI created the JT format as a lightweight and versatile solution for visualizing and sharing 3D data in industries such as manufacturing and engineering.

In 2001, EAI was acquired by UGS Corporation, which later became Siemens Digital Industries Software. Siemens recognized the potential of the JT format and continued its development, expanding its capabilities and promoting its adoption in various industries. Over the years, Siemens has worked to enhance the format, improve its compression techniques, and ensure compatibility with a wide range of software applications.

The JT format gained further recognition and acceptance when it was standardized by the International Organization for Standardization in 2012 as ISO 14306. This ISO standardization solidified the JT format's position as a reliable and widely supported file format for 3D visualization and data exchange. Today, the JT format continues to evolve and is utilized by numerous companies and industries worldwide for effective collaboration, efficient data sharing, and immersive 3D visualization.