The Khronos 3D Formats Working Group has been busy on a new glTF specification, glTF 2.1, that extends glTF’s capabilities beyond holding a single asset to complex scenes. glTF 2.1 also includes improvements that streamline the journey of an asset from authoring and format conversion, through asset management and optimization, to delivery and toolchain integration. While the specification is nearing completion, the opportunity is still open for community feedback.
(Source: Khronos)
The Khronos 3D Formats Working Group released glTF 2.0 nine years ago, and this open-standard 3D asset format continues to gain widespread industry adoption. The Working Group has big plans for the next release, glTF 2.1, with expanded core features that will provide robust support for complex scenes. The Khronos group says glTF 2.1 will be “a focused, backward-compatible revision of the core specification, built around a primary motivation—making glTF work as well for large, composed scenes as it already does for single assets.”
This major update will expand glTF’s support for use cases such as digital twins, building information modeling (BIM), smart cities, geospatial representation, simulation environments, progressive scene streaming, LOD hierarchies, and large-scale collaborative environments.
Today, applications using glTF typically turn to proprietary methods or custom tooling when working with complex scenes, limiting interoperability. This new release aims to eliminate those issues.
Figure 1. glTF 2.1 complex scene features at a glance. (Source: Khronos)
glTF 2.1 means that developers building large-scale scenes now have a standardized way to compose and deliver multi-file scene graphs. Also, applications needing 3D streaming can build on complex scenes as the foundation for progressive delivery—including spatial subdivision, availability maps, LOD, and quality metrics, and streaming hints already proven at scale by the glTF extensions forming the 3D Tiles standard developed by the Open Geospatial Consortium—now integrated into core glTF.
While the Khronos 3D Formats Working Group is focused on widening the spec’s scope, it has not turned its back on glTF’s core mission as a delivery format: the efficient, reliable transmission and loading of 3D assets at runtime. Rather, complex scenes extend what glTF can deliver—complete, composed, multi-asset experiences rather than just single models—without turning glTF into an authoring format. glTF 2.1 is complementary to content creation ecosystems such as OpenUSD, in that scenes authored and assembled in creation pipelines can be delivered as self-contained and interoperable glTF assets.
“This release has been guided by a clear philosophy: address the most impactful, widely needed improvements to the core spec while keeping glTF lean, interoperable, and backward-compatible,” said Amanda Morgan, Khronos 3D Formats co-chair and senior director, Open Standards at Bentley Systems. “Each feature has gone through a structured ‘Design First’ process: Working groups agreed on purpose, scope, behavior, and relationships before any schema work began, ensuring that every addition earns its place in the core.“
In addition, glTF 2.1 will deliver quality-of-life improvements, each yielding efficiencies in development and deployment pipelines:
Figure 2. glTF 2.1 other improvements to eliminate areas of development and deployment friction. (Source: Khronos)
The glTF 2.1 specification is being developed openly on the glTF 2.1 GitHub; and community feedback is welcome as the specification is finalized.
Discussions will also be held at the seventh annual glTF Ecosystem Forum during Siggraph on July 23 from 2:00–7:00 pm, giving attendees the opportunity to share feedback and engage with the Working Group directly on the glTF 2.1 roadmap and the wider glTF ecosystem; space can be reserved here.
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