glTF (GL Transmission Format)

Major game engines have integrated native glTF support for asset pipelines and runtime loading.

• Unity: Uses glTF through the UnityGLTF package for importing and exporting.
• Unreal Engine: Supports glTF via plugins and built-in importers for architectural visualization and web pipelines.
• Godot: Features built-in glTF 2.0 support as a core import format. This allows artists to create assets once and deploy them across multiple engine targets.

Essential for mobile and web-based AR/VR where bandwidth and performance are critical. Platforms leverage glTF for its ability to stream complex 3D models efficiently.

• Google's ARCore and Apple's ARKit recommend glTF (via USDZ or direct support) for AR objects.
• Microsoft uses it for mixed reality experiences.
• Meta supports glTF for 3D posts and Quest development. Its PBR material system ensures consistent visual fidelity across devices.

E-commerce platforms and configurators use glTF to display interactive, photorealistic product models. Its small file size allows for quick loading on product pages.

• Shopify supports 3D models for merchants, primarily using glTF.
• Amazon has implemented AR View, which uses compatible 3D formats including glTF.
• IKEA Place and similar apps use it to let users visualize products in their home space.

Used as a lightweight visualization and collaboration format. Heavy CAD (e.g., STEP, IGES) and BIM (e.g., IFC) files are often converted to glTF for review, marketing, and digital twin applications. Tools like Autodesk Viewer and SimScale can consume glTF to share and interact with complex engineering models in a web browser, decoupling visualization from proprietary design software.

The foundational asset format for interoperable virtual worlds and digital replicas of physical systems. Its role as a transmission format makes it ideal for streaming assets into live, persistent environments.

• Platforms like NVIDIA Omniverse use USD as a scene descriptor but glTF for individual assets.
• Mozilla Hubs and other web-based social VR spaces rely on glTF for user-generated content.
• Digital twin platforms use it to visualize IoT data in a 3D context.

As a runtime asset format, glTF is optimized for fast loading and rendering on mobile and headset hardware, which is critical for AR/VR experiences. It supports features essential for immersion:

• PBR materials for realistic lighting.
• Animations (skinned, morph target) for character movement.
• Extensions for advanced effects like KHR_lights_punctual. This makes it the preferred format for platforms like Microsoft Mesh, Mozilla Hubs, and various VR applications.

glTF acts as a foundational interoperability standard for metaverse platforms and digital twins, allowing 3D assets to move between different engines and environments. Use cases include:

• Creating persistent virtual worlds where user-generated content is portable.
• Building accurate digital twins of factories, cities, or supply chains for simulation and monitoring.
• The format's support for scenes, nodes, and cameras provides the structural hierarchy needed for complex virtual environments.

While game engines often use proprietary formats for final builds, glTF serves as a crucial intermediate or source format in the asset pipeline. It is widely supported for import/export by:

• Unity (via the GLTF Utility package).
• Unreal Engine.
• Blender and other DCC (Digital Content Creation) tools. This streamlines workflows, allowing artists to create a model once in a tool like Blender and export it as a .glb file for use across multiple engines and projects.

glTF is becoming the standard for representing 3D goods in digital marketplaces and for Non-Fungible Tokens (NFTs). Its advantages for commerce are:

• Self-contained. The .glb binary format packs all textures and data into one file.
• Platform-agnostic. Buyers can view the asset on web, mobile, or in VR.
• Standardized. Ensures fidelity and functionality are preserved when an asset is transferred. This is critical for verifying the authenticity and appearance of a 3D NFT across different wallets and viewers.

Industries use glTF for high-fidelity, interactive technical documentation and sales configuration tools. Examples include:

• Automotive: Allowing customers to visualize car models with different paint, wheels, and interiors in real-time.
• Manufacturing: Displaying complex machinery parts with exploded views and assembly animations.
• AEC (Architecture, Engineering, Construction): Sharing lightweight, interactive models of building MEP (Mechanical, Electrical, Plumbing) systems for collaboration and client review.

glTF is part of a family of 3D formats, each with distinct purposes.

• OBJ/Wavefront: A simple, text-based format for static 3D geometry and materials, widely supported but lacks scene hierarchy and animation.
• FBX (Filmbox): A proprietary, feature-rich format from Autodesk for exchanging 3D assets between authoring tools, supporting animations, rigs, and cameras.
• USD (Universal Scene Description): A high-performance, extensible framework from Pixar for composing complex, non-destructive 3D scenes, crucial for film and industrial workflows.
• glTF's role is to be the optimized, runtime-friendly counterpart to these authoring formats for web and real-time applications.

glTF is designed to natively support Physically Based Rendering (PBR), a shading model that simulates real-world light interaction for realistic materials. Key PBR components in glTF include:

• Base Color: The albedo or diffuse color of the material.
• Metallic/Roughness: A two-component model where the metallic value defines if a surface is dielectric (non-metal) or conductor (metal), and roughness defines surface micro-roughness.
• Normal Map: A texture that simulates fine surface detail without adding geometry.
• Occlusion, Emission: Additional maps for ambient occlusion and emissive surfaces. This standardization ensures assets look consistent across different rendering engines.

The glTF specification is extended via a formal extension system to support new features without breaking core compatibility.

• KHR (Khronos) Extensions: Vendor-neutral, ratified extensions that become part of future core specifications. Examples include KHR_lights_punctual for lights and KHR_materials_unlit for non-PBR materials.
• EXT (Multi-Vendor) & Vendor Extensions: Experimental or vendor-specific features, like EXT_mesh_gpu_instancing or MSFT_audio_emitter.
• Extension Declarations: A glTF file declares which extensions it uses, allowing clients to gracefully handle unsupported features. This modularity is key to glTF's adaptability.

glTF is the primary 3D asset format for web-based graphics APIs.

• WebGL: A JavaScript API for rendering 3D graphics in browsers without plugins, based on OpenGL ES. glTF's JSON+bin structure maps efficiently to WebGL buffers and textures.
• WebGPU: The next-generation web graphics API providing lower-level, more efficient access to GPU hardware. glTF is equally foundational for WebGPU, with loaders and renderers optimized for its modern pipeline. Frameworks like Three.js and Babylon.js provide high-level abstractions for loading and rendering glTF with both APIs.

To reduce file size and improve loading performance, glTF supports mesh and geometry compression.

• KHR_draco_mesh_compression: A Khronos extension that uses Google's Draco library for lossy compression of mesh geometry (vertices, indices), achieving significant size reduction with minimal visual impact.
• EXT_meshopt_compression: An extension using the Meshoptimizer library for fast, efficient compression of vertex attributes, animation, and morph target data. It is designed for fast decoding on the client side. These compression techniques are critical for delivering complex 3D experiences over the network.