CV-2x3-156 (aka CV-06-156)

Agreement on exporting CAD presentation layer for elements [modified 2011-03-20 & 2011-05-03]

Based on          IFC2x3

Initiator            ISG Meeting-Amsterdam

Effects              Extended Coordination View

Date                    2008 06 24

Description:

The CAD presentation layer assignment, IfcPresentationLayerAssignment, is assigned to an element by:

    * mandatory assignment to a single CAD presentation layer for the whole element, using the assignment of IfcShapeRepresentation to IfcPresentationLayerAssignment)

          - NOTE: if the wall have different assignments to CAD presentation layer (e.g. one per each wall material layer) it is the task of the sending application to decide about the "main" CAD presentation layer.

    * optionally, individual wall, slab, or plate material layers can have an additional assignment to CAD presentation layer (different per material layer) when using the IfcMaterialDefinitionRepresentation assignment).


Addition 2011-03-2020

Initiator: Coordination View Version 2.0 Model View Definition

The original agreement has been extended to all elements having shape representation (the word "wall" has been replaced by "element" in the agreement text above). For all subtypes of IfcElement (with the exception of IfcFeatureElement subtypes, and IfcVirtualElement) that have a representation provided by one or many IfcShapeRepresentation's the following requirement applies:

    * for all IfcShapeRepresentation with the RepresentationIdentifier="Body" the inverse relation LayerAssignments to IfcPresentationLayerAssignment shall be provided.

    * for all other IfcShapeRepresentation, having an RepresentationIdentifier not equal to "Body", the inverse relation LayerAssignments to IfcPresentationLayerAssignment may be provided, but it is not required.


Addition 2011-05-03

Initiator: Coordination View Version 2.0 Model View Definition

The following clarification has been added:

    * the IfcPresentationLayerAssignment for the "Body" representation, and the other representations (like "Axis", or "FootPrint", if assigned to a CAD presentation layer) can be either the same CAD presentation layer or different onces.

    * if the subtype of IfcElement has aggregated parts, and those parts have the "Body" shape representation, then the parts are required to have an assignment to the CAD presentation layer. See also Implementer Agreement CV-2x3-119. If the IfcElement (representing the whole) has an own shape representation (required to be different to "Body" by CV-2x3-119) it maybe assigned to a CAD presentation layer but is not required to.


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