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What is a glTF file?

glTF (GL Transmission Format) describes a 3D scene as a hierarchy of nodes, with meshes, materials, textures, cameras and animations. Its goal is to minimize the size of 3D assets and the processing needed to display them, so that the same file can be loaded quickly by web browsers, game engines, AR/VR applications and mobile viewers.

A glTF asset can be stored in two ways. The .gltf form is a JSON file that references binary buffers and images, either as separate files or embedded in the JSON. The .glb form packs everything into a single binary file, which is easier to share and faster to load. The format can also be extended with additional JSON data and official extensions, for example for mesh compression.


glTF vs. GLB

Feature.gltf.glb
StructureJSON file, with separate or embedded binary data and imagesSingle binary container
ReadabilityThe JSON part can be read and edited as textNot human-readable
Number of filesOften several (JSON, .bin, textures)One
Typical useDevelopment, debugging, pipelinesDistribution, web viewers, AR/VR apps
ContentSame scene descriptionSame scene description

What Is glTF Used For? Applications and Industry Use Cases

glTF has become a standard delivery format for real-time 3D: product configurators and e-commerce viewers, web-based design reviews, augmented and virtual reality, digital twins of products, production systems and facilities, and game engines. Its compact, run-time optimized structure makes it well suited to streaming 3D content to any device.

For software developers, glTF export is the bridge between engineering data and these experiences. An application can read native CAD models, tessellate them and publish lightweight glTF or GLB assets that web and XR viewers can display without any CAD software.


Challenges or Common Pitfalls

glTF is a visualization format. Converting a CAD model to glTF replaces exact B-rep geometry with meshes, so the result is meant for display, not for engineering changes or manufacturing. Choosing the right tessellation quality is a balance between visual fidelity and file size.

Some CAD content needs special care. Mirror transforms, for instance, change the handedness of an object and are not valid instance transforms in a glTF scene, so they must be handled during conversion. Compression extensions such as Draco greatly reduce file size, but the target viewer must support them.


How Spatial Helps

Our 3D InterOp SDK writes glTF files in both .gltf and .glb form, a capability introduced in Release 2023 1.0. You can export facet data imported from any format that 3D InterOp reads, or authored in your application, and multi-level assemblies are written as a glTF scene graph.

Exported models keep their color and transparency, and wires, points and PMI can be included through a visualization data option. World orientation can be set at product structure, reference or part level, and Draco mesh compression is enabled by default to reduce file size, with settings to turn it off or tune quantization.

Combined with native CAD import, this lets your application turn engineering models into compact, web-friendly 3D assets for visualization, virtual experiences and digital twins. Check the 3D InterOp documentation for supported glTF versions and current limitations.

Dassault Systèmes

Siemens

Autodesk

Standards

Other

  • Pro/E / Creo
  • Rhino
  • MicroStation DGN
  • AVEVA
  • Smart3D

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