Geometry conversion for IFC Export

These settings define how to convert the geometry of ARCHICAD elements exported to IFC.

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Export only geometries which “Participates in Collision Detection”

Exports only elements whose ARCHICAD Building Material includes the “Participates in Collision Detection” option ON. (This is set at Options > Element Attributes > Building Materials > Properties).

Use this option to export composite elements and complex profiles, which don’t have solid geometries, as real air gaps. This way, MEP engineers (who receive the ARCHICAD IFC file) can place pipes in the gaps without collision detection; only element parts which have real geometry will participate in collision detection.

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See also Collision Detection.

Export Bounding Box

Exports the dimensions of the building elements’ bounding box.

Export Geometry of IFC Type Products

Assigns a representative geometry to each Type Product. (This option is required for Concept Design BIM 2010.)

Each type (e.g. IfcFurnishingElementType) will use a representative geometry of the elements that belong to it (e.g. IfcFurnishingElement).

Use BREP geometry in current color for all elements

All model elements are exported using BREP (Boundary Representation) geometry. BREP is precise but non-parametric geometry.

The elements will be exported in the color displayed in the current ARCHICAD view, including colors defined by Graphic Overrides, Renovation Status, and Mark-Up Corrections or Highlights.

Triangulate surfaces of BREPs (effective only with IFC4 Schema)

BREP geometry is saved as triangulated surfaces - an option preferred by some model visualization applications when importing IFC files. This option - which only works if you are using the IFC4 Schema - produces a compact geometrical description, which might reduce file size.

Explode Composite and Complex Profile elements into parts

Saves composite elements and Complex Profiles as so-called “Building Element Parts”. This means that the main element (e.g. IfcWall) will be saved as a Container element without geometry, and its parts (the skins or profile components) will provide the geometry.

This export option retains the original colors of all building parts, instead of exporting the element in all one color.

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Multi-skin complex geometries (Effective only with IFC 2x3 Schema)

Note: Not applicable if “Explode Composite and Complex Profile elements” box is checked, above.

Choose how to handle components of multi-skin, complex elements exported to IFC.

This option affects multi-skin (Composite or Complex Profile) ARCHICAD elements having complex (e.g. slanted) geometry representation.

Building element parts: Creates multiple sub-elements, each with its own geometry and material information. Each sub-element is assigned the IFC material or profile that is represented by its Building Material (Cut Fill) in ARCHICAD.

Complex profiles: The complex geometry is converted to a single IFC element with a profile geometry and an IFC material. (The receiving application will not know the precise order of the different components/skins.)

Note: This option is affected by the “Partial Structure Display” (Document menu) currently in effect in ARCHICAD, if the view’s visible elements are being exported. For example, if the exported model uses “Core Only” display, then the “Complex profiles” option will have no effect on a slanted composite wall with a single core, because the visible wall consists of a single core skin.

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Elements in Solid Element Operations

Extruded/revolved: This method can retain the elements’ parameter values (such as thickness, height, location of reference line or edge). The skin structure of composite materials cannot be fully preserved because of the IFC standard’s limitations. Certain specialized sections are not retained.

This is the format usually supported by static analysis programs, in which element parameters are important, but their special cut angles (such as the slanted edge of a slab) are not important.

BREP: This method provides the most exact reproduction of element geometry, together with its specialized sections and connections. However, the element’s parameters are lost, and BREP (Boundary Representation) elements are transformed into non-editable elements. This method is useful in the “reference model” workflow.

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Elements with junctions

Extruded/Revolved without junctions: Elements are exported without the priority-based intersections, resulting in a faster export process. This option is recommended for structural analysis programs, for which the elements’ reference lines/surface information is sufficient, and detailed intersections are not required.

BREP: Elements are exported together their junctions, for precise geometry.

The difference in the two export methods is illustrated here:

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Slabs with slanted edge(s)

Extruded: Slabs will be exported with vertical edges (even though their original geometry included a slanted edge.)

BREP: Slabs will be exported with precise geometry, recreating the slanted slab edges.

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Use legacy geometric methods as in Coordination View 1.0:

Use this option if you have created your own, custom MVD that is based on the geometry methods of Coordination View version 1.0.

IFC Site geometry

Choose how to represent ARCHICAD Site Geometry exported to IFC.

ARCHICAD elements will be considered Site Geometry if they are classified using “IfcSite” as their IFC Type. (See Type Mapping for IFC Export.)

Note: If you are mapping by Element Type instead of by Classification, save the element as an Object having the Subtype “IFC Site”.

Choose one of the following site geometry methods, depending on which one the receiving application can read:

Solid body: Geometric representation as solid bodies, enclosed by their superficies and boundary surfaces. All faces are planar and all edges are straight lines.

Top surface only: Geometric representation of the superficies (top surface) only.

Top surface as wireframe: Geometric representation with contours and points.

Note: ARCHICAD can import all three of these IFC site geometry representations.

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Export structural openings and holes as separate elements

In this parameter, “Openings” refers to the voids occupied by Doors, Windows, and Skylights in their host element, as well as any holes in structural elements (e.g. in Beams, Slabs or Roofs).

Note: Holes created in Solid Element Operations are not considered.

In IFC, these exported openings will remain related to their host elements (e.g. Wall) and to the Door/Window/Skylight, if any.

Choose an option to specify this export parameter:

Always: The holes and voids are always exported as separate elements, regardless of the method by which their host element (e.g. Wall) is exported.

For example: A wall containing a window is exported to IFC with this option. The resulting IFC file contains three exported elements: wall, window, and the window opening (void). Their interrelationship remains intact. The exported opening/void is not a visible model element, but it is listed in the IFC file hierarchy.

For extruded/revolved elements only: Only the openings of elements exported as extruded/revolved are exported as separate elements. Elements using the BREP export method are already exported with holes in them; in this case, their openings are not added to the exported file as separate elements.

For example: A wall containing a window is exported to IFC with this option. The wall (based on other Geometry Conversion options) is being converted using the BREP method. Thus, the “openings as separate elements” does not apply. The resulting IFC file contains two exported elements: wall and window, unrelated to each other.

Match IFC Site location with:

Define location of the IFC Site entity (its coordinate system), if a Survey Point has been defined in ARCHICAD. (See also Using Survey Point in ARCHICAD, below.)

ARCHICAD Project Origin: Locate the IFC Site entity at the Project Origin if you are working close to the ARCHICAD Project Origin, yet still wish to define model coordinates relative to a national datum (using the Survey Point). This way, a far offset is stored in the IFC file not as part of the element coordinates, but rather generally. See the following illustration:

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ARCHICAD Survey Point position: Locate the IFC Site entity at the position of the Survey Point. Use this if you are working at a long distance from the Project Origin, yet you don’t want large offsets to be present in the IFC file (usually with legacy models). See the following illustration:

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Notes:

If the ARCHICAD project does not contain a Survey Point, then the IFC model’s global coordinate system origin and the IFC Site Location will be the ARCHICAD Project Origin.

If the ARCHICAD project contains multiple Survey Points (though it is recommended to use just one), then the first placed Survey Point will be used. (A warning will alert you to this.)

The program will consider the Survey Point even if it is not visible in the exported view (i.e. if it is on a hidden layer)!

Using Survey Point in ARCHICAD

ARCHICAD has a Survey Point object, which can be used as common reference point to facilitate coordination of models from different programs. In some countries, use of a particular reference point is a standard requirement when defining the project.

The position and rotation of the Survey Point defines the global coordinate system (X=0, Y=0, Z=0) of the IFC model. When defining this point position in ARCHICAD, it is recommended to consider the True North direction (use the default “Follow Project North” parameter). At IFC export, this parameter defines the direction of the Y axis in the global coordinate system.

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Notes:

In ARCHICAD, True North is defined by Project North (Options > Project Preferences > Project Location)

The Survey Point is always created at IFC Open. In case of Merge IFC, the model is imported to be aligned to the host file’s Survey Point.

For more information on Survey Point in ARCHICAD, see the Help Center article at: https://helpcenter.graphisoft.com/tips/open-bim/survey-point-is-now-supported-at-ifc-importexport/.

Mapping IFC Location Data From ARCHICAD and Revit

IFC

ARCHICAD 20 and up

Revit

IFC Global Origin

Survey Point

Survey Point

Position of IfcSite entity

Project Origin

Project Base Point

Hierarchical ARCHICAD Elements Exported to IFC

Define how to handle Curtain Walls, Stairs and Railings exported to IFC:

Convert to single element: The hierarchical element is exported as a single IFC entity, which contains within itself the geometry of all its sub-elements. The hierarchical nature of the original element (e.g. Stair, with all its separate sub-components) is thus lost.

Keep hierarchy: Retain the original element’s hierarchical structure, including sub-elements.

See also Exporting Hierarchical Elements from ARCHICAD as IFC Containers.

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