[x3d-public] X3D Working Group Minutes, 2 SEP 2022: X3D glTF feature comparison

Fri Sep 2 11:53:31 PDT 2022

The Extensible 3D (X3D) Working Group coordinates all Web3D Consortium
technical development efforts.  Working groups are essentially driven by the
efforts of participants. They focus on issues and technologies that produce
improvements to our open standards, always achieving results that are
royalty free for any purpose.  All efforts are geared towards improving a
coordinated set of steadily evolving ISO standards including X3D Version 4.

*	Web3D Consortium Working Groups
*	https://www.web3d.org/working-groups

Attendees: Bill Benman, Anita Havele, Dick Puk, Don Brutzman.

1.	Today we worked to update the following comparison spreadsheet (HTML
version below, .pdf also attached).

*	Features Comparison X3D 4.0 and glTF 2.0
*
https://docs.google.com/spreadsheets/d/1x0DnRtg33AuOA_aSl70L41Gq5m6TFt4t/edi
t#gid=1010586376

Comments and improvements to these feature comparisons are welcome.  Have we
expressed everything precisely and correctly?

2.	We further considered recent news regarding World Wide Web
Consortium (W3C) getting rechartered as a 501c3 non-profit organization, and
how that might influence Web3D Consortium which is chartered as a 501c6
non-profit organization.

*	W3C will become a public-interest non-profit organization. W3C is
replacing its original Hosted model and boosting its crucial web standards
work.  In the months leading to the launch of a new legal entity in January
2023, we will release further details.  
*	https://twitter.com/w3c/status/1542135556007763968
*	https://www.w3.org/2022/06/pressrelease-w3c-le.html.en

3.	Next week we will consider Web3D inputs to a draft Metaverse
Standards Forum (MSF) document regarding feature sets for technical
interoperability.

Consortium and community members are welcome to participate.  As usual, we
meet each Friday.

*	X3D Working Group, Fridays 0900-1000 pacific
*
https://us02web.zoom.us/j/81634670698?pwd=a1VPeU5tN01rc21Oa3hScUlHK0Rxdz09

Web3D Consortium membership has value.  Please consider joining to maximize
your ability to benefit and influence.

*	Join the Web3D Consortium
*	https://www.web3d.org/join

Have fun with X3D and glTF!   8)

Features Comparison X3D 4.0 and glTF 2.0

2 August 2022

References

X3D 4.0 specification

https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-DIS/Part01/
Architecture.html

glTF 2.0 specification

https://github.com/KhronosGroup/glTF/tree/master/specification/2.0

IEEE 3D Body Processing Paper 

https://standards.ieee.org/downloads/3DBPWhitePaper.pdf

IEEE 3DBP Features 

https://docs.google.com/spreadsheets/d/15wCQ8CHJnQD_tmwaRPFfZqBe6KJzE1CzOKd2
XOlPL4M/
<https://docs.google.com/spreadsheets/d/15wCQ8CHJnQD_tmwaRPFfZqBe6KJzE1CzOKd
2XOlPL4M/edit#gid=416054782> 

IEEE 3DBP Working Group

https://standards.ieee.org/develop/wg/3DBP.html

Value Proposition

X3D is a file format allowing 3D scenes to be used by a wide variety of
applications.

X3D can be used by Web browsers and other viewers, authoring tools, 3D
Printing applications, text editors, and XML tools.

X3D is the appropriate choice if the primary goal is saving your interactive
3D scenes for use over time and multiple applications.

glTFT (GL Transmission Format) is a specification for efficient transmission
from server to client.

glTF is the appropriate choice if the primary goal is viewing 3D scenes in a
Web browser.

Technology Comparison Summaries

X3D: A royalty-free open ISO standards file format and run-time architecture
to represent and communicate 3D scenes and models.

X3D: Data Interchange and Rendering format, useful for both general Web
deployment and diverse 3D applications.

X3D: Interoperability with other "vertical" functional domains and
international Web standards.

X3D: Metadata Support is thorough, working groups are currently mapping to
external metadata vocabularies.

X3D: Stable long-term archival stability and re-usability, two decades of
proven capability.

X3D: Ensure portability and consistency across multiple file formats,
programming languages and platforms.

X3D: Forward/backward compatibility and extensibility are specification
goals that have been demonstrated successfully for 20 years.

X3D: Strong intellectual property rights (IPR) policy, no cost-bearing
patents allowed, IPR fully aligned with W3C Web standards.

X3D: Strong community, wide industry compatibility, many
importers/exporters, many standards-organization liaisons.

X3D: Full Inline support for glTF features, especially compressed geometry
plus advanced lighting model planned for X3D version 4.

glTF is a royalty-free specification for efficient transmission and loading
of 3D scenes and models.

glTF: Transmission format designed for applications rendering using WebGL or
OpenGLES.

glTF: A run-time delivery system for highly optimized mesh data for
rendering, delivered from source to client.

glTF: Always changing to support the fast changing GPU, a delivery system
for highly optimized mesh data for rendering.

glTF: Backward compatibility, archivability, are not listed as specification
goals. 

glTF: Strong community, good industry support.

Feature 

X3D Support v4.0

glTF Support (v2.0 binary + ASCII)

Triangular meshes

Yes

Yes

Points and lines

Yes

Yes

Quad meshes

Yes

No

Primitive shapes: box, sphere, cone, cylinder, text

Yes

No

NURBS curves and surfaces

Yes

No

CAD Structure (assemblies)

Yes

No

Animation (general)

Yes

Yes

Picking (touch/over TouchSensor, PickableGroup)

Yes

Yes

Clipping planes

Yes

Yes

Human animation: skeleton, skin, motion

Yes, including anatomically correct humans 

Yes, ad hoc anatomy

Morph targets

HAnim displacers

Yes

Skin/joint animation

Yes 

Yes

Scripting

Yes

No

Extensibility by authors (prototype mechanism)

Yes

No 

Metadata Structures

Complete support, now mapping vocabularies

Partial, in separate files

Annotation

Planned X3D v4.1; experimental support now

No

Material

Yes

Yes 

Physically Based Rendering, advanced lighting

X3D v4.0, matching glTF

Yes (e.g. metallic-roughness model)

Custom Shader

Yes (multiple shader languages supported)

No

Bump mapping

Yes

Yes

Occlusion map

Yes

Yes

Emissive map

Yes

Yes

Normal map

Yes

Yes

Image (2D) texturing

Yes (image files or embedded pixel map)

Yes

Texture mapping

Yes

Yes

Volume (3D) textures, imaging

Yes

No

Movie (2D + time) texturing

Yes (optional support for streaming)

No

Audio

Yes (optional support for streaming)

No

Spatial 3D Audio

Yes

No

Inline

Supports X3D, scripts, glTF

?

Formats/encodings

ASCII (XML, ClassicVRML, JSON, languages)

Binary & ASCII (JSON based)

Binary: .x3db, Efficient XML Interchange (EXI)

Inline glTF

Security

Yes (optional signature and encryption in XML)

No inherent encryption

(X3D note: collection of animation displacers equivalent to HAnim morph
target)

all the best, Don

-- 

Don Brutzman  Naval Postgraduate School, Code USW/Br        brutzman at nps.edu

Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA    +1.831.656.2149

X3D graphics, virtual worlds, Navy robotics https://
faculty.nps.edu/brutzman

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