4.8.2.8 Reference Geometry

A specific form of geometry representation is the 'Reference' geometry. It is used to provide a geometry used for various forms of assessments (like for quantities, etc.) but not for display and also not for implicit Boolean operations in a voiding relationship.

EXAMPLE  An example is the use of 'Reference' representation is for opening elements that shall not be used to create a void using the IfcRelVoidsElement relationship, since the voids are already part of the 'Body' representation of the voided element.

The representation identifier of the representation is:

• IfcShapeRepresentation.RepresentationIdentifier = 'Reference'

Figure 79 illustrates an instance diagram.

Figure 79 — Reference Geometry

mvdXML Specification

<?xml version="1.0"?>
<ConceptTemplate xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" uuid="d68f9f1b-223a-4a8a-912b-b83f032a74f2" name="Reference Geometry" status="sample" applicableSchema="IFC4" applicableEntity="IfcProduct">
  <Rules>
    <AttributeRule AttributeName="Representation">
      <EntityRules>
        <EntityRule EntityName="IfcProductDefinitionShape">
          <AttributeRules>
            <AttributeRule AttributeName="Name" />
            <AttributeRule AttributeName="Description" />
            <AttributeRule AttributeName="Representations">
              <EntityRules>
                <EntityRule EntityName="IfcShapeRepresentation">
                  <AttributeRules>
                    <AttributeRule AttributeName="ContextOfItems">
                      <EntityRules>
                        <EntityRule EntityName="IfcGeometricRepresentationContext" />
                      </EntityRules>
                    </AttributeRule>
                    <AttributeRule RuleID="Identifier" AttributeName="RepresentationIdentifier">
                      <EntityRules>
                        <EntityRule EntityName="IfcLabel">
                          <Constraints>
                            <Constraint Expression="Identifier[Value] = 'Reference'" />
                          </Constraints>
                        </EntityRule>
                      </EntityRules>
                    </AttributeRule>
                    <AttributeRule RuleID="Type" AttributeName="RepresentationType">
                      <EntityRules>
                        <EntityRule EntityName="IfcLabel" />
                      </EntityRules>
                    </AttributeRule>
                  </AttributeRules>
                </EntityRule>
              </EntityRules>
            </AttributeRule>
          </AttributeRules>
        </EntityRule>
      </EntityRules>
    </AttributeRule>
  </Rules>
</ConceptTemplate>


  Link to this page