A new standard for assets that works in real time, masters PBR, is still open and is supported by all the big names? Yes, it does exist.
According to Wikipedia, “A standard is a comparatively uniform, widely recognised and usually applied (or at least aspired to) way of describing, producing or performing something that has prevailed over other ways or is at least considered a guideline”. With this in mind, the Khronos Group, a consortium of global industry members, came together to create a standard for the real-time visualisation of 3D assets. The requirements for the standard format were a platform-independent, fast and realistic representation of products as interactive 3D objects. Last but not least, the format should also be capable of augmented reality and the 3D assets should look the same on every common viewer.
After much research, discussion and negotiation, glTF (GL Transmission Format) was chosen as the leading licence-free transmission format for the three-dimensional representation of models and scenes. In order to create a legally compliant and high-quality framework, the decision was made in favour of a certification process in accordance with ISO/IEC JTC 1. The process is already underway and confirmation is expected in the course of 2022.
Why do we need a standard for this?
In the 3D format specialist group, leading international experts from Khronos members are specifying standards in the form of glTF extensions, which are aimed at a realistic representation of materials, but also take file size, metadata, etc. into account. We will read more about examples later in the article. Even if the standards are technically correctly taken into account in DCCTools, there can be very large differences in the presentation. The worst case scenario for creatives would be to painstakingly create a 3D asset in the 3D tool of their choice, only to realise that they have to spend several hours adapting it for integration on different platforms.
To avoid this additional work, the 3D Commerce standard and the certification for 3D RealtimeViewer were created. This group includes well-known representatives from all disciplines of e-commerce, such as Amazon, Ikea, Wayfair or Target, but also from the 3D asset creation and editing sector, such as Adobe, Autodesk, Blender, etc. This new demand also provides scope for new players on the market, such as UX3D GmbH from Munich, which has launched the first visual glTF editor called Gestaltor.
How is the file structured and what data is included?
glTF is short for Graphic Language Transmission Format. It contains three-dimensional scenes and models. A glTF file contains either a glTF (JSON/ ASCII) or a GLB (binary) as a possible file extension. A GLB file is completely self-contained. A glTF file can be self-contained or refer to external binary and texture resources.
The glTF standard supports 3D model geometry, appearance, scene graph hierarchy and animation. The aim was to achieve a streamlined and interoperable format for the delivery of 3D assets, while minimising file size and runtime processing. Khronos likes to draw a comparison with the established JPG format from the 2D world and refers to glTF as “JPG for 3D”.
How does glTF differ from FBX, for example?
The main difference between glTF and other established exchange formats such as FBX is the open standard versus the proprietary approach. For example, the FBX format is best used in the environment of Autodesk products. However, if the format is required for an independent 3D real-time display on the web, mobile or as an augmented reality application, there is no way around glTF. Because it is an open standard, it is even explicitly desired to develop extensions for glTF, which are then ideally also ratified as official KHR_extensions.
What is a compliant glTF? Are there non-compliant glTFs?
A valid glTF is characterised, for example, by its official extensions, which are identified by the prefix “KHR_”. They guarantee the same understanding of physically based rendering in terms of transmission, clear coat, etc.
The following official extensions are currently published:
- KHR_draco_mesh_compression
- KHR_lights_punctual
- KHR_materials_clearcoat
- KHR_materials_pbrSpecularGlossiness
- KHR_materials_ior
- KHR_materials_sheen
- KHR_materials_specular
- KHR_materials_transmission
- KHR_materials_unlit
- KHR_materials_variants
- KHR_materials_volume
- KHR_mesh_quantisation
- KHR_texture_basisu
- KHR_texture_transform
- KHR_xmp_json_Id
A complete list for validating a valid glTF can be found on the Khronos GitHub here: github.com/KhronosGroup/ glTF-Validator.
Where are the problems with compliant glTFs in everyday life?
The challenges we often hear from 3D artists are as follows: A 3D artist creates a 3D object in the DCC tool of choice. This can often take several hours. It is all the more annoying when the artist realises that effects or information are not displayed correctly when exporting to glTF or that some proprietary functionality cannot be mapped in glTF at all. Brand owners and product managers are annoyed when the 3D viewer in the DCC tool and the viewer on the target platform (e.g. in the web shop) are displayed differently and materials or colours are suddenly displayed completely differently. Fortunately, there is a solution for both cases: simply use products certified by 3D Commerce.
The following viewers and a glTFEditor are currently certified by Khronos (as of October 2021)
-
- UX3D: Gestaltor (glTF editor)
- Unity Technologies: Unity glTFast –
4.1.0-preview.1 - CGTrader: CGTrader Viewer – 1.11.10
- Babylon.js: Babylon.js Sandbox –
5.0.0-alpha.24 - Khronos Group, Inc: 3DC-SampleViewer
And in everyday work?
The digitalisation of objects or products traditionally begins in a CAD or design tool or using scanners. 3D digital creation tools come into play to display the result in 3D and optimise it if necessary. Up to this point, the format of the 3D object is always a proprietary format. There are some free conversion programmes or integrated exporters for converting to the real-time format. The next step is to validate the glTF again for quality control purposes and, if necessary, to optimise the size, polygon count, lighting, etc. Before the 3D object can be loaded onto the respective platform, its requirements must be taken into account. On a smaller scale, 3D artists can certainly map the process from start to finish.
The challenge begins with the generation of several hundred assets per day. Currently, parts of the processes can already be implemented semi-automatically. Many platform operators are working together with tool manufacturers to standardise and automate processes. The biggest challenges currently lie in the various platform requirements with regard to the size of the geometry, referenced material representation, quality assurance, etc. In particular, there is still no consensus on the realistic representation of materials in real time: the furniture and clothing industries demand realistic representation of wood, stone, glass, fabrics, etc. This will be all the more important if e-commerce develops even more strongly and printed catalogues are phased out, as IKEA, for example, announced in a press release at the end of last year. We expect to see a standardised solution for displaying some materials in the coming months. As an open source DCC tool, Blender is naturally widely used and is therefore very often chosen as a reference tool for exchanging formats. The Khronos Group has therefore also commissioned the development of a state of the art importer and exporter for glTF. As long as Blender supports all official glTF extensions, they will be exported correctly. To test whether a glTF is valid and all Khronos extensions work, the official sample viewer from Khronos is available at github. khronos.org/glTF-Sample-Viewer-Release. If you want to go deeper into the analysis, you will do yourself a favour by installing the Gestaltor, because an analysis is started as soon as the glTF is loaded and an error report is output in the logger.
Gestaltor
For those who want to integrate the format deep into their pipeline: Gestaltor is the first visual glTF editor that allows you to work natively with the glTF and GLB file formats in compliance with all official Khronos glTF standards (glTF 2.0 and higher) – which we have developed. In principle, the Gestaltor can be operated like any conventional DCC tool. The special thing about it is that only the functionalities relevant to glTF are deliberately included. So you can be sure: The result is always 100% glTF. No more, but also no less – WYSIWYG (What You See Is What You Get). It offers a powerful interface to massively accelerate workflows in the 3DAsset pipeline. The core functionalities are viewing, checking, editing, optimising and creating scenes. 3D content creation in standard DCC tools remains completely unaffected by the workflow. Gestaltor acts as the final link in the workflow to create a 100% valid glTF.
Gestaltor is officially 3D commerce certified by the Khronos Group. This means that all glTF and GLB files created in Gestaltor will look the same on the upcoming certified viewers from Amazon, Babylon.js, CGTrader, Emersya, Epic Games (Unreal Engine), Facebook (Spark AR), Google ( & Scene Viewer), Samsung (Internet Browser on Android), SketchFab, Unity and many others. In the private sector, the community version of Gestaltor tends to be used to open glTFs and to add or remove assets or slightly change the colour, lighting or materials. In the commercial sector, we know that digital agencies use Gestaltor for customer solutions in the augmented reality sector. In expert forums, we read that there is currently no other alternative on the market that can be used to display transmission effects in real time, for example. We usually work with Gestaltor’s enterprise customers in the form of a strategic project to optimise its use in existing 3D workflows.
Manufacturers are often looking for a way to visualise special materials or effects in real time. To this end, our experts develop a prototype in close consultation with the customer, which is then integrated into Gestaltor as an experimental extension. This is what happened with the KHR_materials_iridescence extension.
What are the next steps for Gestaltor?
One of our main priorities in the further development of Gestaltor is to always be 100% in line with the glTF standard; i.e. as soon as official CHR extensions are ratified, we aim to be the first tool to integrate them. Thanks to the very open exchange with Gestaltor customers and strategic project partners, we have prioritised some features higher or added them to the roadmap. Without giving too much away, by the end of 2021, we will have overhauled the entire UI, added an experimental CHR material iridescence extension, a sophisticated material import (pbr2gltf2) and basic animations. The ambitious plan is that we will continue to establish Gestaltor as the world’s leading DCC tool for glTF.
What is coming in the next versions of glTF?
We are currently seeing a big movement from many industries towards glTF. Automotive manufacturers are already in the process of completely converting their 3D visualisation pipelines for human machine interfaces to glTF and open standards. Representatives of standards for videos and audio files are currently discussing with Khronos sensible options for delivering this data with glTF as well. For the fast-moving consumer goods industry, there are several factors in favour of adding glTF to the pipeline. Firstly, a high-quality 3D real-time asset can replace product photography, and the official extension for metadata khr_xmp_json_ld could be used to supply all information from EAN codes to product descriptions.
What role will Khronos play in the future?
The role of the Khronos Group seems to be constantly strengthening through the development of many useful standards. With the development of the mixed reality market, OpenXR as a standard is here to stay.
Even the otherwise very restrictive Apple Safari browser is opening up to WebGL 2.0 support by the end of 2021. Games built with the Vulkan standard, such as Fortnite or all games on Google’s Stadia, are also proving to be relevant on the market. And it is not yet possible to predict what else will emerge in the direction of WebGPU. Of course, all developments in the direction of augmented reality and metaverse speak in favour of glTF, with Spark AR, Snap AR, TikTok AR, NFT in art and the digital fashion industry etc. opening up promising business models. If you want an overview of all the standards at a glance, you can find them on the official website at www.khronos.org.
What is the future of standards?
The demand for standards from major market players in all industries has become so great that even competing advocates of proprietary formats are sitting down at the same table to reach joint compromises. For us, this is a sign that sooner or later no technology provider will be able to avoid open standards. Just as USD is a valid framework for the internal co-operative exchange of 3D computer graphics, we believe that glTF is the optimal format for the exchange of 3D real-time graphics across platforms to the outside world.
What requirements for interoperable formats such as glTF will we see in 2040?
A democratic desire for non-proprietary solutions could become the norm – business models may change to the extent that users decide what they want to consume with which devices and technologies, and a requirement is established that content and usability are the same regardless of the platform. But we will see.
