Assigning Property Values in ARCHICAD (Based on IFC Property Mapping)

For general information on setting up the Property Mapping preset: see Property Mapping for IFC Import.

For each imported element, ARCHICAD attempts to execute the applicable mapping rules.

A mapping rule is applicable if the ARCHICAD Property is available to the element (based on its Classification).

The value of the mapped IFC property is assigned to the element’s corresponding ARCHICAD Property. (It is a custom value.)

Example: Mapping Rule Applied

We have set up a mapping rule in the Property Mapping for Import preset of the current IFC Translator. According to this rule, the IFC property called Example_A is mapped to the ARCHICAD Property called Product Info A.

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A Column, with an IFC data called “Example_A”, is imported from an IFC file.

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Element’s Data in Source IFC File (as seen in Model Viewer)

The mapping rule is successfully applied: the Column element generated during import has a property called Product Info A, which is assigned a custom value (in ARCHICAD Element Settings, the Property value is displayed with the unlinked icon - it is no longer linked to its default value, set in Property Manager.)

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Target ARCHICAD Property with Custom Value, after Element Import from IFC

Example: Non-Existent IFC Data

If a mapping rule refers to IFC property data that do not exist for the incoming element, then the element’s ARCHICAD Property value becomes Undefined.

Two mapping rules are shown. One of them refers to an IFC data (Example_C) that does not exist for the element being imported.

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Element’s Data in Source IFC File (as seen in Model Viewer)

As a result, this mapping rule will assign the custom value of <Undefined> to the target ARCHICAD Property.

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Target ARCHICAD Property with Custom <Undefined> value, after Element Import from IFC

Incompatible Data Types

If the mapped IFC element has a value, but it cannot be interpreted by the corresponding ARCHICAD Property (e.g. incompatible data types): no custom Property value is assigned. The element uses the ARCHICAD Property’s default value.

Note on Data Types:

IFC and ARCHICAD use different data type definitions: See Data Types for Properties in IFC and ARCHICAD. When you map an IFC Property to an ARCHICAD property, their data types do not necessarily have to coincide. ARCHICAD attempts to convert the data.

If data conversion is not possible, the Session Report provides details on which elements’ IFC data could not be converted.

Example

Two mapping rules are shown. One of these maps the “Example_A” IFC data (a string-type IfcLabel) to the Thermal Transmittance ARCHICAD Property, which is a String-type value. The mapping rule is successfully applied: the element generated during import shows a String-type custom value for the ARCHICAD Property of Thermal Transmittance.

The second mapping rule maps the “Example_A” IFC data to the Combustible ARCHICAD Property, which is a True/False type value. The data types do not match, so the mapping rule gets a Warning icon.

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Mapping Rule to “Combustible” Property Referencing Incompatible Data Type

The targeted ARCHICAD Property does not get any custom value: it remains linked to its default value.

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Property Mapping with Incompatible Data Types: No Change to ARCHICAD Property Value

If no mapping rule applies to an element’s given Property, then no custom Property value is assigned. The element uses the ARCHICAD Property’s default value.

Conflicting Mapping Rules

The mapping table may include several IFC Properties mapped to the same single ARCHICAD Property. In this case, ARCHICAD will use the most specific rule. (The order in which the rules appear in the mapping table does not matter.)

In case of two or more equally specific mapping rules: the rules are ignored, and no mapping takes place.

A rule becomes more specific as its IFC data properties are more narrowly defined. (For example, IFC PropertySet data set to “Any” is less specific than if it is a defined IFC PropertySet.) Within a mapping rule, each field to the right further narrows its definition.

Here, two IFC data (Example_A and Example_C) are mapped to the same ARCHICAD Property. In this case, the more specific rule is automatically applied. Example_C is more specific, since it is narrowed down at the level of IFC PropertySet.

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In the next example:

Several Thickness-related IFC Properties are mapped to a single Thickness Property in ARCHICAD. If an imported IFC element comes with multiple Thickness properties, then ARCHICAD has no way of determining which Property value to use in ARCHICAD. Thus, the rules are ignored for this imported element, and its ARCHICAD Property value remains the default one.

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