Classification, Revit and IFC’s

June 6, 2014
Stephan

BIM is the implementation of CAD tools such as Revit and the production of 3D.. Not correct on many levels, but this blog post will deal solely with “Classification”..

My constant refrain is that BIM is at its heart about the exchange of information and this is ONLY (i repeat) ONLY achieved when the information schema is not just non-proprietary (aka OPEN) but also able to include the breadth of information required to reflect the industry for which it is designed… IFC or “Industry Foundation Classes” is that format (it’s even been elevated to being an ISO standard ISO16739). So no, your .rvt file is not BIM, its the antithesis of BIM.

The distinction is further demonstrated when one looks at the fashion in which Revit deals with classification of objects, apart from being generally woeful the mighty Autodesk have seemingly failed to understand the correct method of defining class in the IFC’s they export. Not wanting to drag you in to overly technical details..

Revit defines object class information by using the IFC class IFCPropertySingleValue; this is a generalised property set vehicle that allows the “free hand” instantiation of information relative to a single object.

The IFC schema does however cater for the description of object class as it really is a key consideration towards information quality..

#91349= IFCRELASSOCIATESCLASSIFICATION(‘_VHsN_EQK4xY8o0_JtjxvL’,#50,$,$,(#85303),#91348);
#91350= IFCCLASSIFICATIONNOTATIONFACET(‘M42.5′);
#91351= IFCCLASSIFICATIONNOTATION((#91350));

This formal approach is key to the future ability to reference this information successfully as industry solutions mature and are driven more by information quality.

To those reading this blog post it is an opportunity to look again at your outputs and push vendors to up their game in the future..

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