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ifcOWL an ontology for building data Pieter Pauwels Ghent University
ifcOWL an ontology for building data
Pieter Pauwels Ghent University
WHAT IS BIM / WHAT IS IFC?
Building Informa>on Modelling
ISO standard file format
• Industry Founda>on Classes • Managed by BuildingSMART • Schema specified in EXPRESS informa>on modelling language
• Number of versions: IFC2X2 – IFC2X3 – IFC4
buildingsmart-‐tech.org
The EXP file
BUILDING AN IFCOWL ONTOLOGY FOR DESCRIBING BUILDING DATA
implementa>on proposals 2005-‐2012
• Diverse sugges>ons in academic research to make IFC available as an OWL ontology to allow the usage of seman>c web technologies
Ø Schevers and Drogemuller, 2005 Ø Beetz et al., 2009
• General purpose ini>a>ve to convert EXPRESS schemas and STEP file to OWL ontology, not focused on IFC
Ø Krima et al., 2009(OntoSTEP) Ø Barbau et al., 2012 (OntoSTEP)
• From 2012 onwards, increasing uptake in research and developments
=> many different ifcOWL structures floa>ng around
• Need for formalisa>on and standardisa>on => combine efforts and proceed in a more formalised, standard fashion => role of standardisa>on bodies: W3C, BuildingSMART
Towards a recommendable and usable ifcOWL ontology
• When: 2nd half of 2014 • Who: Pieter Pauwels (Ugent) and Walter Terkaj (ITIA-‐CNR) • What: dis>ll ONE recommended conversion procedure for conver>ng an
EXPRESS schema into an OWL ontology, based on earlier efforts. • Results:
– Conversion procedure documented in ar>cle manuscript and separate slideshow
– Implemented in JAVA (hcps://github.com/mmlab/IFC-‐to-‐RDF-‐converter/tree/BS) and C++ converter
– Resul>ng ontologies: • hcp://linkedbuildingdata.net/resources/IFC4_ADD1.owl • hcp://linkedbuildingdata.net/resources/IFC2X3_TC1.cl
conver>ng EXPRESS schema to OWL IFC
Schema
Simple data type
Defined data type
Aggrega>on data type SET data type -‐-‐-‐-‐-‐-‐-‐-‐
LIST & ARRAY data type -‐-‐-‐-‐-‐-‐-‐-‐
Constructed data type
SELECT data type -‐-‐-‐-‐-‐-‐-‐-‐ ENUMERATION data type -‐-‐-‐-‐-‐-‐-‐-‐
En>ty data type
Acributes -‐-‐-‐-‐-‐-‐-‐-‐
Derive acr WHERE rules
Func>ons Rules
ifcOWL Ontology owl:class + owl:DatatypeProperty restric>on owl:class owl:class -‐-‐-‐-‐-‐-‐-‐-‐ owl:ObjectProperty restric>on on
ifc:hasSet -‐-‐-‐-‐-‐-‐-‐-‐ indirect subclass of ifc:List owl:class -‐-‐-‐-‐-‐-‐-‐-‐ owl:unionOf ( owl:classes ) -‐-‐-‐-‐-‐-‐-‐-‐ one of ( owl:NamedIndividuals ) owl:class -‐-‐-‐-‐-‐-‐-‐-‐ object proper>es -‐ -‐ -‐ -‐
ifcOWL ontologies available
Ifc2x_all_lf.exp IFC2X2_ADD1.exp IFC2X2_FINAL.exp
IFC2X2_PLATFORM.exp IFC2X3_Final.exp IFC2X3_TC1.exp
IFC4.exp IFC4_ADD1.exp
not supported not supported not supported not supported IFC2X3_Final.owl / .cl IFC2X3_TC1.owl / .cl IFC4.owl / .cl IFC4_ADD1.owl / .cl
hcp://www.linkedbuildingdata.net/resources/IFC2X3_Final.cl hcp://www.linkedbuildingdata.net/resources/IFC2X3_TC1.cl hcp://www.linkedbuildingdata.net/resources/IFC4.cl hcp://www.linkedbuildingdata.net/resources/IFC4_ADD1.cl
CLASSES INDIVIDUALS OJECT PROPERTIES
RESTRICTIONS
I WANT TO HAVE IFCOWL INDIVIDUALS
Op>on 1 – Manual modelling from scratch using an ontology editor
1. Not all IFC restric>ons (rules, derive acributes, func>ons) available in ifcOWL => no complete consistency checking
2. Tedious and error-‐prone process
limita>ons
Op>on 2 – Automa>c modelling from scratch using APIs
im = ModelFactory.createDefaultModel(); im.setNsPrefix("ifcowl", ontNS); im.setNsPrefix("inst", baseURI); for (int i = 0; i < inst.getList().size(); i++) {
OntClass cl = ontModel.getOntClass(ontNS + typeName); Resource r = im.createResource(baseURI + typeName + "_" + inst.getLine_num(), cl);
}
1. Not all IFC restric>ons (rules, derive acributes, func>ons) available in ifcOWL => no complete consistency checking
2. Need to build modelling applica>on anew, relying on a different sopware library at the basis
limita>ons
Op>on 3 – Conversion of exis>ng IFC SPFF Files
Free open file-‐to-‐file conversion service: hcp://smartlab1.elis.ugent.be:8889/IFC-‐repo/
1. Two dis>nct applica>ons, two dis>nct models -‐> versions can go out of control 2. The converter can become a bocleneck
limita>ons
COMMUNITY EFFORTS
Joining / combining ini>a>ves
W3C LBD Community Group BuildingSMART LD Task Force
linkedbuildingdata.net
www.w3.org/community/lbd/
…
linkedbuildingdata people
LDAC event
