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 and implementations
  • Approved ISO standard Compressed Binary Encoding (CBE) for X3D
  • Optional gzip compression and MIME Type definitionsptional gzip compression and MIME Type definitions are included for .x3dz/.x3d.gz, .x3dvz/.x3dv.gz and .x3db.gz file extensions
    • Original compression technique of gzip compression for .wrl VRML called .wrz (TODO need reference)
  • Based on ISO standard Fast Infoset (FI) for XML compression
  • Two independent open-source implementations available
    • C++ codebase: XIOT X3D Input Output Tool library
    • Java codebase: Xj3D
    • Ongoing status: 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

• Polygon reduction
  • CAD Distillation Filter (CDF) technique allowing successive refinement of large X3D scenes into tighter X3D scenes
  • Extensible, repeatable compression-decompression 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, ensuring that 3D Model Compression, Serialization and Transmission use-case requirements are defined and met
  • 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
  • This meets most needs of digital authors for digital rights management

• 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

• 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