Arch IFC

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L'atelier architecture contient un importateur (IFC). Le format IFC est un format de plus en plus répandu pour l'échange de données entre les applications BIM, utilisés en architecture et en ingénierie.

L'importateur est toujours en cours de développement et dépend d'un logiciel externe open-source appelé IfcOpenShell. Il n'est pas fourni avec FreeCAD et doit être installé sur votre système. Si IfcOpenShell est correctement installé, il sera détecté par FreeCAD et utilisé pour importer des fichiers IFC. Il est toujours possible de forcer l'utilisation de l'ancien importateur IFC python qui ne dépend pas d'IfcOpenShell en activant l'option associée dans les paramètres de préférences Arch. Ce dernier importateur a été arrêté et ne pourra importer qu'un petit sous-ensemble d'objets IFC.

The use of IfcOpenShell is highly recommended, since it is much faster and more powerful than the internal parser. IfcOpenShell supports all IFC2x3 and IFC4 entities that carry geometry information, not all of them can be converted to Arch objects, those that can't will be imported as simple Part shapes.

Importing

All IfcProduct-based entities from IFC2x3 or IFC4 files will be imported into the FreeCAD document. The IFC preferences settings allow you to set how the IFC objects are imported: as full parametric Arch objects, as non-parametric Arch objects, as non-parametric Part shapes, or as one Part shape per floor. Each of these types looses some information over the previous one, but is lighter on resources, which allows to open bigger files. A last type allows to discard entirely the importing of Arch objects, which is useful for structural analytic models.

If parametric Arch objects are used, for all IFC types that have an equivalent in the Arch Module, the corresponding type is used. For the others, a generic Part shape is created. All Arch objects, parametric and non-parametric, will carry the full set of IfcProperties attached to each object.

IfcAnnotation objects are also imported, as well as linear and curve-based IfcStructuralItem-based entities.

Enabling the show debug messages in the IFC preferences settings will print a report indicating if any object from the IFC file failed to import.

Exporting

Exporting to IFC files will export all the selected objects and their descendants. To export a whole building or a whole floor, it is only needed to select the building or floor object. Arch objects will be exported with the type set in their "Role" property. Their IfcProperties are exported as well, and if these objects have an IFC UID from a previous import, the same UID will be kept at export. Objects that are not Arch objects are exported as IfcBuildingElementPRoxy.

IFC files are exported as IFC2x3 or IFC4 depending on your version of IfcOpenShell, which can be compiled with any of the IFC schemas.

If the shape of exported objects is based on an extrusion or a boolean operation, the operation and components will be correctly exported to IFC. If not, the object's shape is exported as IfcFacetedBrep. If the shape contains curves, these will be faceted.

Links

Tutorial Import/Export IFC - compiling IfcOpenShell