Creating or Editing Mapping Formulas

Use formulas in the IFC mapping settings to provide more detailed control over the data that is exported for drawing objects. Field mapping formulas adjust the data for the selected object in specific IFC entity and Pset fields. Conditional mapping formulas assign IFC entities and Psets to the selected object based on specific conditions.

As described in more detail in IFC Data Mapping Expressions, a mapping formula contains expressions with constants, variables, operators, and functions. A variable is a data source from Vectorworks, such as an object parameter, record field, class name, or style data. Functions can be math functions, string manipulation functions, conditional, and selector functions.

Conditional Mapping Formulas

Use conditional mapping formulas for situations where objects do not have a simple one-to-one correspondence with a specific IFC entity or property set.

●        Some plug-in objects should be assigned to different IFC entities, depending on what the object’s settings are, or what the object’s “style” is. For example, a framing member object could be IfcBeam, IfcMember, or IfcColumn.

●        Aggregate objects generate more than one IFC entity. For example, a curtain wall object should be assigned to the IfcCurtainWall entity primarily, but its member and plate sub-elements should be assigned to the IfcMember and IfcPlate entities.

●        In some situations, different property sets might be assigned to an object, depending on conditions. For example, some building elements, such as protruding slabs, can act as shading devices. Those elements have their primary purpose as IfcSlab, but they should also have Pset_ElementShading attached to them.

For an IFC entity, a conditional formula should yield a specific IFC entity to be used for the object; if the result is empty or a non-valid IFC type, the object will not be exported. For a property set, the formula should yield a true or false value; if the value is false or if there is no result, the property set will not be exported.

Field Mapping Formulas

IFC field mapping formulas calculate and display the values of certain property set parameters, to map standard BIM data to IFC-compliant data, or to map custom property sets.

●        In the IFC Data Mapping dialog box, select a field associated with an object to display the mapping formula on the right side of the dialog box.

●        In the IFC Data dialog box, the mapping formula displays in the Data Source parameter of the selected property (see Assigning IFC Data to Objects).

Study the default data mapping formula to help you understand the data source of the mapped IFC values. Then use IFC Data Mapping Expressions to customize the default formula.

Creating Formulas

To create a mapping formula:

1. From the IFC Data Mapping dialog box, select the object, and then select the field or condition to map. The current formula displays in the pane on the right side of the dialog box. Here is an example:

 

2. Click Define Mapping or Define Condition.

The Define Mapping or Define Condition dialog box opens.

Minor syntax edits can be made directly to the formula. For example, add a prefix and/or suffix, or add concatenation or arithmetic operations to the formula. See Entering Formulas in Worksheet Cells for information about arithmetic operations.

Click to show/hide the parameters.

Parameter	Description
Obtain initial mapping value from	Select the general value to be used for mapping from the list of possible values, and then select the specific value to use from the secondary list, or enter the value
Additional Mapping values	Specifies a value set to use if the one specified above it is not available
More Choices	Adds another row of values to use in case the ones above it are not available; up to ten choices can be added (although with formulas, the number of choices can be expanded as needed)
Fewer Choices	Removes the most recently added row of values
Formula	Displays the mapping formula based on the selected building blocks

3. Build the formula by selecting the mapping values and specific parameters from the lists.

The mapping formula displays in the IFC Data Mapping dialog box.

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IFC Data Mapping Expressions

IFC Data Mapping Examples

Mapping IFC Data

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