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Extract the Envelope

Data and Spatial visualization

Extractions are twofold: the invisible part is the set of data that pertain to the spatial unit at hand. On these data, processes can be run to provide metrics / indicators (surfaces and volumes, space types and usage, energy transfer, life cycle, reuse, ...).

The visible part is there to help understand the structure of the spatial unit, but also to identify issues, such as components that exibit misclassification and other anomalies.

Extraction based on object properties

Construction Objects (Walls, Slabs, Columns, Beams, Doors, Windows, ...) have standardized property sets Pset_WallCommon, Pset_SlabCommon, Pset_ColumnCommon, PsetBeamCommon, Pset_DoorCommon, Pset_WindowCommon, ... that typically have one of their properties related to the fact that is object is (or is not) external.

Therefore it is possible to select external objects based on that information.

Extraction of the envelope of Duplex_A_20110907_optimized

Hereunder, we have the result of the extraction. Top and bottom slabs are not included (data issue). Party walls are also marked as external (data issue). We have highlighted the upper party wall.

BIMCollab display of Duplex_A_20110907_optimized envelope

Extraction of the envelope of IFC Schependomlaan

Hereunder, we have the result of the extraction. We have hidden the top slabs (roof) to see inside the building. We have highlighted a floor slab to be sure that we can see through the construction to the floor.

BIMCollab display of IFC Schependomlaan envelope

Extraction of the envelope of NordicLCA_Housing_Concrete_BuildingPermit

Hereunder, we have the result of the extraction. We have hidden the top slabs (roof) to see inside the building. We have highlighted a floor slab to be sure that we can see through the construction to the floor.

We have also the slabs of the terraces which are rightly marked as external but should be removed from the envelope with a more sophisticated filtering (= some more python code).

BIMCollab display of NordicLCA_Housing_Concrete_BuildingPermit envelope

Extraction of the envelope of NordicLCA_Office_Concrete_BuildingPermit

Hereunder, we have the result of the extraction. We have hidden the top slabs (roof) to see inside the building. We have highlighted a floor slab to be sure that we can see through the construction to the floor.

BIMCollab display of NordicLCA_Office_Concrete_BuildingPermit envelope

The IfcEnvelopeExtractor

There are other ways to extract the envelope of a building, but often limited to the geometry which is not our main focus.

It is however worth mentioning the IfcEnvelopeExtractor. It enables users to automatically extract the building shell of an IFC-model and convert it to a CityJSON model. Automating this process allows designs to be quickly and easily analyzed on a city scale without the need for lengthy manual conversions. This is one of the steps required to close the gap between architecture/BIM and city scale models.