X3D Binary Compression Capabilities and Plans

Synopsis. Lots of work has been accomplished towards proper support of X3D Binary Compression for a wide variety of potential uses.

Standards

• Approved ISO standard Compressed Binary Encoding (CBE) for X3D
  • Based on ISO standard Fast Infoset (FI) for XML compression
• Optional gzip compression and MIME Type definitions
  • XML encoding (.x3dz/.x3d.gz), ClassicVRML encoding (.x3dvz/.x3dv.gz) and Compressed Binary encoding (.x3db.gz) file extensions
  • Original compression technique of gzip compression for .wrl VRML called .wrz (TODO need reference)

Polygon reduction and geometric compression

• CAD Distillation Filter (CDF) technique allowing successive refinement of large X3D scenes into tighter X3D scenes
• Extensible, repeatable compression and decompression algorithms for data-flow production chains
• Multiple filters implemented in open-source Xj3D and X3D-Edit
• Multiple other conversion and translation tools available with supporting capabilities
• X3D Canonicalization (C14N) provides standardized formatting so that digital signatures are not thwarted by whitespace variations

Binary encodings

• Plan to add a further-improved X3D Compressed Binary Encoding using now-approved W3C Recommendation for Efficient XML Interchange (EXI)
• Web3D contributed to EXI working group and XML Binary Characterization working group efforts
  • 3D Model Compression, Serialization and Transmission use-case requirements are defined and met by EXI
• Design includes compatibility with CDF techniques, XML Encryption, and XML Digital Signature for author authentication
  • Relevant example scenes maintained as part of X3D Basic Examples Archive - Security
• These capabilities meets most needs of digital authors for digital rights management (DRM)

Networking

• Several capabilities are available for flexible network transmission
• Anchor, Inline, LOD, LoadSensor, Script and Prototype nodes support successive retrieval of content once initial model is displayed
• TODO: Willing to consider further addition of progressive-mesh geometric streaming technologies, perhaps by a public Call for Contributions
  • For example, the original X3D Compressed Binary Encoding Request For Proposals (RFP)
• Intellectual Property Rights (IPR) protections for X3D specification
  • Patented technologies can be considered, but only when eventual use will be royalty free for X3D use (if eventually accepted)
  • Submitters can restrict patented submissions to working group while under consideration, if desired
• TODO: Use cases and test examples can demonstrate whether http/https and local-file url retrieval are sufficient for a network protocol
  • • Other network protocols (Web sockets, P2P channels, etc.) might be possible, but only if security restrictions can be handled satisfactorily

Implementations

• Two independent open-source implementations available
  • C++ codebase: XIOT X3D Input Output Tool library
  • Java codebase: Xj3D
  • Ongoing status is maintained on Web3D-member wiki pages: Player_support_for_X3D_components and Tool_support_for_X3D_components
• Several thousand X3D Examples available in .x3db form, encoded by Xj3D
  • TODO: Plan to similarly automate conversions with XIOT for cross-check validation testing

Looking ahead

• Web3D's X3D and CAD Working Groups each have member commitments to pursue this continued innovative work in 2012
• TODO: A workshop might be a rapid way to compare candidate technologies that might complete these capabilities
• X3D appears to have have an 80% solution already available that meets various requirements for a general 3D transmission format