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X3D Ontology for Semantic Web

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The X3D Ontology for Semantic Web provides terms of reference for semantic query of X3D models.

Motivation | Download | Design and Design Patterns | OWLDoc | Queries | References | Tools | TODO | Contact

🔖 Motivation to top

Extensible 3D (X3D) Graphics is the royalty-free open standard for publishing, viewing, printing and archiving interactive 3D models on the Web.

The X3D Semantic Web Working Group mission is to publish models to the Web using X3D in order to best gain Web interoperability and enable intelligent 3D applications, feature-based 3D model querying, and reasoning over 3D scenes.

Motivating insights:

"The answer to your question is the response to the query." Jim Hendler and Dean Allemang
"Trying to use the Semantic Web without SPARQL is like trying to use a relational database without SQL." Tim Berners-Lee
"The proof of the pudding is in the eating." Wiktionary

To learn more about publishing 3D graphics on the Web, please see What is X3D? and X3D Version 4 Overview.

🔖 Download to top



Version Control

All work is maintained using subversion at Sourceforge version control under a non-viral Web3D Consortium open-source license (text).

🔖 Design to top

The current X3D Ontology is reasonably stable as we work to make X3D models queriable in interesting ways. These representations fully match the functionality of X3D4.

TODO. More work remains for the X3D Ontology. Expected progression, with adjacent steps typically in tandem:

  1. Continued review of .ttl representations generated from X3DUOM.
  2. Establishing satisfactory URI matching website URL, e.g. (website request pending).
  3. Building an extensive set of SPARQL queries.
  4. Autogenerate and publish RDF-A for all X3D examples, following patterns in Leslie Sikos' book.
  5. Defining use cases for queries and demonstrating examples.
  6. Define similar/corresponding triple constructs for different 3D formats, building upon Leslie's 3dmo.ttl exemplars.
  7. Investigate existing vocabularies and tools for visual 3D shape search including potential analysis and annotation of models.
  8. Use Apache Daffodil (DFDL) to actually parse and subsequently query those other formats coherently.

🔖 Design Patterns

  1. Triple names. Each triple must be uniquely named. Please note that these names are ID labels that can be matched and reported, but the text used for each name cannot be reasoned against.
  2. FontStyle and ScreenFontStyle nodes each have a style field. This has been renamed as styleSelection to avoid query collisions when contained in a Web page.
  3. More to follow.

🔖 Queries to top

X3D Semantic Web Working Group efforts include defining use cases for queries and demonstrating examples, which will like follow three general patterns:

build.all.log.txt and build.SPARQL.query.tests.log.txt each provide a full set of queries and responses. These build logs help practitioners compare results and track progress (or setbacks).

🔖 Graph (triple store) SPARQL Query         SPARQL Response Description



X3dOntologyQuery_01.rq X3dOntologyQuery_01.rq.txt Metaquery (against X3D Ontology itself) to list all properties with corresponding domains and ranges.
X3dOntologyQuery_02.rq X3dOntologyQuery_02.rq.txt Metaquery (against X3D Ontology itself) to list nodes and statements (concrete owl:Class) with inherited node types and object types.
X3dOntologyQuery_03.rq X3dOntologyQuery_03.rq.txt Metaquery (against X3D Ontology itself) to list all geometry nodes.
X3dOntologyQuery_04.rq X3dOntologyQuery_04.rq.txt Metaquery (against X3D Ontology itself) to list all X3D default simple-type field values (ontology annotationProperties).
X3dOntologyQuery_05.rq X3dOntologyQuery_05.rq.txt Metaquery (against X3D Ontology itself) to list all X3D literals (enumeration constants).



X3dHelloWorldQuery_01.rq X3dHelloWorldQuery_01.rq.txt Query HelloWorld.ttl to count number of Shape nodes, with expected result = 2 nodes.
X3dHelloWorldQuery_02.rq X3dHelloWorldQuery_02.rq.txt Query HelloWorld.ttl to show url values within an ImageTexture node.
X3dHelloWorldQuery_03.rq X3dHelloWorldQuery_03.rq.txt Query HelloWorld.ttl to show title given to model within a WorldInfo node.
X3dHelloWorldQuery_04.rq X3dHelloWorldQuery_04.rq.txt Query HelloWorld.ttl to show contained geometry, appearance, material and texture field SFNode values within each Shape node.
X3dHelloWorldQuery_05.rq X3dHelloWorldQuery_05.rq.txt Query HelloWorld.ttl to show all nodes in 'children' field contained within any Group node.



X3dSanCarlosCathedralAltarQuery_01.rq X3dSanCarlosCathedralAltarQuery_01.rq.txt Query SanCarlosCathedral Altar.ttl to show the number of shapes composing the altar.
X3dSanCarlosCathedralAltarQuery_02.rq X3dSanCarlosCathedralAltarQuery_02.rq.txt Query SanCarlosCathedral Altar.ttl to show url addresses of all textures used within the scene.
X3dSanCarlosCathedralAltarQuery_03.rq X3dSanCarlosCathedralAltarQuery_03.rq.txt Query SanCarlosCathedral Altar.ttl to determine Background skyColor values.



HelloX3dAuthorsAnimationChainQuery_01.rq HelloX3dAuthorsAnimationChainQuery_01.rq.txt Query HelloX3dAuthorsAnimationChain.ttl to determine ROUTE parameters of interest.
AllDocumentMetaInformation.rq AllDocumentMetaInformation.rq.txt Query HelloX3dAuthorsAnimationChain.ttl to identify all document meta information.
DocumentMetaProperties.rq DocumentMetaProperties.rq.txt Query HelloX3dAuthorsAnimationChain.ttl to identify specific document meta properties of interest.



DocumentMetadataValues.rq DocumentMetadataValues.rq.txt Query MetadataNodeExamples.ttl to list all values found in Metadata nodes.


Several thousand XML-based .x3d models in the X3D Example Archives have been converted into .ttl Turtle triples, using the X3dToTurtle.xslt conversion stylesheet.

Both .ttl and SPARQL query results are available for each model, as illustrated in the screenshot for the HelloWorld example catalog entry.

Comprehensive conversion and test-query results for all models in X3D Resources, Examples: Scene Archives for X3D are listed in build.turtle.all.log.txt. This is a comprehensive set of unit tests for X3D ontology, xslt model conversion into .ttl, and SPARQL query.

🔖 References: Books, Papers and Workshops, Specifications to top


  1. Dean Allemang, James Hendler and Fabien Gandon, Semantic Web for the Working Ontologist: Effective Modeling for Linked Data, RDFS and OWL, third edition, ACM Books, 2020.
  2. Jakub Flotyński, Knowledge-Based Explorable Extended Reality Environments, Springer, 2020.
  3. Don Brutzman and Leonard Daly, X3D for Web Authors Morgan Kaufmann Publishers, Elsevier, April 2007.
  4. Bob DuCharme, Learning SPARQL, second edition, OReilly Media, Sebastopol, 2013.
  5. Leslie F. Sikos, Mastering Structured Data on the Semantic Web: from HTML5 Microdata to Linked Open Data, Apress Springer Science+Business Media, New York, 2015.
  6. SPARQL on Wikibooks covers both the language and a powerful Web-based GUI, the Wikidata Query Service SPARQL endpoint.
  7. William Kent and Steve Hoberman, Data and Reality, Technics Publications, third edition, 2012. "A timeless perspective on perceiving and managing information in our imprecise world." (excerpts) (goodreads) (Owen Ambur)
  8. Jose E. Labra Gayo, Eric Prud’hommeaux, Iovka Boneva, and Dimitris Kontokostas, Validating RDF Data, Synthesis Lectures on the Semantic Web: Theory and Technology, Vol. 7, No. 1, DOI: 10.2200/S00786ED1V01Y201707WBE016, Morgan & Claypool, 2018.

Papers and Workshops

  1. Pascal Hitzler, "A review of the semantic web field," Communications of the ACM, Vol. 64, No. 2, January 2021. "Tracing the triumphs and challenges of two decades of Semantic Web research and applications." Includes video overview.
  2. Metadata and Semantics for Web3D Workshop ( at Web3D 2019
  3. Preservation, Access, and Reuse: Advancing 3D and VR Strategy in the Research Library (pptx) by Jamie Wittenberg, Indiana University at Web3D 2019
  4. X3D Ontology for Semantic Web was presented as a "Lightning Talk" at US Semantic Technologies Symposium (US2TS). Raleigh North Carolina, 9-11 March 2020.
  5. R.C. Jackson, J.P. Balhoff, E. Douglass, N.L. Harris, C.J. Mungall, and J.A. Overton, ROBOT: A tool for automating ontology workflows. BMC Bioinformatics, vol. 20, July 2019.


  1. X3D Specifications: Schema and DOCTYPE Validation provides assets commonly used for XML validation of X3D scenes.
  2. X3D Recommended Standards provide a coordinated set of steadily evolving ISO standards which are Royalty Free (RF) and publicly available for any use.
  3. OWL 2 Web Ontology Language, Document Overview (Second Edition), W3C Recommendation, 11 December 2012.
    The OWL 2 Web Ontology Language, informally OWL 2, is an ontology language for the Semantic Web with formally defined meaning. OWL 2 ontologies provide classes, properties, individuals, and data values and are stored as Semantic Web documents. OWL 2 ontologies can be used along with information written in RDF, and OWL 2 ontologies themselves are primarily exchanged as RDF documents. This document serves as an introduction to OWL 2 and the various other OWL 2 documents. It describes the syntaxes for OWL 2, the different kinds of semantics, the available profiles (sub-languages), and the relationship between OWL 1 and OWL 2.
  4. RDF 1.1 Semantics, W3C Recommendation, 25 February 2014.
    This document describes a precise semantics for the Resource Description Framework 1.1 [RDF11-CONCEPTS] and RDF Schema [RDF11-SCHEMA]. It defines a number of distinct entailment regimes and corresponding patterns of entailment. It is part of a suite of documents which comprise the full specification of RDF 1.1.
  5. SPARQL 1.1 Query Language, W3C Recommendation, 21 March 2013.
    RDF is a directed, labeled graph data format for representing information in the Web. This specification defines the syntax and semantics of the SPARQL query language for RDF. SPARQL can be used to express queries across diverse data sources, whether the data is stored natively as RDF or viewed as RDF via middleware. SPARQL contains capabilities for querying required and optional graph patterns along with their conjunctions and disjunctions. SPARQL also supports aggregation, subqueries, negation, creating values by expressions, extensible value testing, and constraining queries by source RDF graph. The results of SPARQL queries can be result sets or RDF graphs.
  6. RDF 1.1 Turtle: Terse RDF Triple Language, W3C Recommendation, 25 February 2014.
    The Resource Description Framework (RDF) is a general-purpose language for representing information in the Web. This document defines a textual syntax for RDF called Turtle that allows an RDF graph to be completely written in a compact and natural text form, with abbreviations for common usage patterns and datatypes. Turtle provides levels of compatibility with the N-Triples format as well as the triple pattern syntax of the SPARQL W3C Recommendation.
  7. Time Ontology in OWL, W3C Candidate Recommendation, 25 March 2020.
    OWL-Time is an OWL-2 DL ontology of temporal concepts, for describing the temporal properties of resources in the world or described in Web pages. The ontology provides a vocabulary for expressing facts about topological (ordering) relations among instants and intervals, together with information about durations, and about temporal position including date-time information. Time positions and durations may be expressed using either the conventional (Gregorian) calendar and clock, or using another temporal reference system such as Unix-time, geologic time, or different calendars.

🔖 Tools to top

Many tools are available for Semantic Web development. Here are the primary ones used for this work.

🔖 Contact to top

Questions, suggestions, additions and comments about this X3D Ontology for Semantic Web page are welcome. Please send them to Don Brutzman and Jakub Flotyński (email brutzman at and flotynski at
Master version of this X3D Ontology for Semantic Web page is available online at and available in Sourceforge version control.
Updated: 28 September 2021