Map properties for exporting IFC files.
By default, Civil 3D exports to IFC include a comprehensive list of Civil 3D and AutoCAD attributes and properties. The infrastructure IFC plugin provides support to control these attributes and properties. Specified attributes and properties can be excluded from the export. Furthermore, the export configuration allows for the resulting IFC property name to differ from the original Civil 3D attribute or property name. Grouping these properties into IFC property sets is also supported. Additionally, it is possible to designate the specific IFC classes to which a particular property will be applicable.
Parameter mapping for exporting IFC files is complex but easy to configure. The IFC 4.3 Extension can generate templates with estimated or default values for mapping Civil 3D entities to IFC classes. The extension uses a hierarchical system, where the most specific setting overrides the more general. You can also exclude entities from the export.
To create project specific property mapping files
- Click Add-ins tab
IFC Infrastructure panel IFC Infrastructure Save Property Templates
.
- In the Save As dialog, click Save. This creates an IFCInfraExportPropertyMapping.csv file and an IFCInfraExportPropertyMapping.json file in the folder of the current drawing.
The IFCInfraExportPropertyMapping.csv file and IFCInfraExportPropertyMapping.json files include general parameters, UDP, pipe part data, and property set data for IFC objects. If mapping files do not exist, then all properties are exported.
In the IFCInfraExportPropertyMapping.csv file, the mapping data displays in 6 columns.
- IFCPropertySet Name. Specifies the name of the property set in the IFC File.
- IFCProperty Name. Defines the property name in the IFC File.
- Active. Specifies whether or not the value is exported. Either True or False.
- Source. Specifies the object source from which the parameter is defined. Either Properties, PartData, General, or PropertySet.
- Group. Specifies the Civil 3D group containing the value.
- Civil 3D Name. Specifies the Civil 3D name of the property.
{
"Export": {
"PropertyTemplatePaths": [
"./TfNSW_Properties.ifc"
],
"PropertyManagementPaths": [
"./TfNSW_Properties.csv"
]
}
}
The IFCInfraExportPropertyMapping.json file defines how parameters are created in the IFC file, any missing entries will cause the export functionality to do a best guess but still export data. It contains an array of IFC Property Group definitions. Each entry in the array contains 4 values and an array of valid value definitions.
{
"PropertySetTemplates":[
{
"Name": "Properties",
"Description": "",
"TemplateType": "NOTDEFINED",
"ApplicableEntities": "IfcElement",
"PropertyTemplates": [
{
"Name": "AutoRebuild",
"Description": "",
"PrimaryMeasureType": "IfcBoolean"
}
]
Injected IFC Properties
It is not always practical to have Civil 3D Extended Property Sets applied to all entities exported to the IFC model, particularly Corridor shapes and links, as well as other IFC objects like the spatial structure. A typical IFC model uses an IfcProject as the primary entity from which to navigate the model.
To enhance the specification of properties for the IfcProject, a CSV file can be created in the IFC output directory. This file must have the suffix "_Project_IFC_Properties.csv" appended to the IFC file name. For instance, in the provided example project, the "exportIFC4x3" folder contains a file named "IFC_Demo_Port_Fairy_Rail_Trail_Project_IFC_Properties.csv". The contents of this CSV file enable the nomination of properties and attributes to be exported on the IfcProject entity.
IFC models typically feature a singular primary spatial structure element, which is referenced by the IfcProject. To specify properties for this element, a CSV file can be created in the IFC output directory with the suffix "_RootSpatialElement_IFC_Properties.csv" appended to the IFC file name. In the example project, the "exportIFC4x3" folder contains a file named "IFC_Demo_Port_Fairy_Rail_Trail__RootSpatialElement_IFC_Properties.csv". This entry element is commonly an IfcSite, but it can also be other facility classes such as IfcRoad or IfcRailway. This configuration is managed within the "IfcInfraConfiguration.json" file in the "IfcExportAs" attribute under "FacilityAttributes".
Civil 3D Corridor links and shapes (or solids) are dynamically calculated entities that are recalculated and regenerated. Consequently, it is not currently feasible to save extended property set data directly on the components of a corridor. However, a CSV-based method allows for the injection of properties and attributes onto corridor components, including the Corridor itself, Baselines, Baseline Regions, Subassemblies, shapes, and links. This CSV file can be generated from Dynamo (or a script) as a computed and updated output prior to export. It is possible to specify attributes and properties for a particular component by nominating its name or code. Additionally, a common property can be specified, such as nominating a shape code, to have the attribute or property generated on all shapes with that code.
The CSV file for corridor properties should be created in the IFC output directory with the suffix "_Corridor_IFC_Properties.csv" appended to the IFC file name. In the example project, the "exportIFC4x3" folder contains a file named "IFC_Demo_Port_Fairy_Rail_Trail__Corridor_IFC_Properties.csv". Within this file, a column at the end provides a description to assist in identifying where the property or attribute should be set within the IFC model.