SEM Family Name & ID

SEM Family Name & ID

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SpatialContainment-01

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1-Header

IFC Release: 2.3.TC1

SEM Member Names & ID

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01-Project-01, 01-Site-02, 01-Building-03, 01-BuildingStory-04, 01-Space-05

Organization: Pankow Foundation, PCI

Creation date: 28/4/2011

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Author(s): Chuck Eastman, GA Tech

Revision History:

C. Eastman, 8/6/2011

C. Eastman 30/8/2011

SEM Description:

The Spatial Containment Hierarchy is part of most Model Views. It categorizes all spatial and building elements according to the aggregation hierarchy of Project, Site, Building, BuildingStory and Space. This hierarchy of spatial elements categorize the spatial area that specific objects are associated with, by enclosure. These volumes are not fixed or predefined, but conceptual.
All Models include a Project, for identification. If it has shapes, it must also include a Site and/or Building, which provides global coordinates. BuildingStory optionally partitions a building vertically and Space partitions regions within a Story further. A Project may span over several connected or disconnected sites; similarly, a Site may incorporate multiple Buildings. Each level is defined as a one-to-many relationship. The Spatial Containment entities should be created prior to the elements that populate them, before other spatial elements are translated, in order to classify objects within this spatial hierarchy as they are created.
An Exchange consists of those within a single Project; thus one Project entity is define. Beneath the project, a Site entity is generated for each Site instance; a Building entity is generated for each one on each Site. For each story within a building, a BuildingStory element is created, in each case, as they are encountered in a model being translated.
The Spatial Containment Hierarchy SEM recognizes that large projects (and files) may be decomposed for hardware and performance reasons, among others. These are identifies within the Spatial Containment hierarchy as CompositionType. Decompositions of hierarchy members are notes as PARTIAL and their aggregation as COMPLEX. We recommend ignoring this capability and to always assign ELEMENT to CompositionType.
The containment structure is a hierarchy; all objects with shapes are classified and assigned to a single location in the hierarchy, using RelContainedInSpatial Structure. Within a Building, some objects span multiple Storys – some columns, vertical circulation, curtainwalls, for example. These would be classified as contained in the Building. This may lead to searching the Building Objects to access all the objects within a Story. To facilitate such accesses, IFC optionally supports an object instance to have multiple references into the Spatial Hierarchy, using RelReferencedInSpatialHiearchy. This can be used to reference an elevator with all the Storys it passes accesses. This optional structure is included in an optional SEM.

SEM Family Name

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Spatial Containment

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2-Relations

Identify SEMs Outside this Family that it Links With

<none>
Potential Child SEMs, if any:
(Some BuildingElement subtypes are not placed in the Spatial Containment structure and are crossed out. They are depicted later as part of Building Components. The elements now being implemented are highlighted and documented here.)
Building Element Individuals / IfcBuildingElementProxy, IfcCovering, IfcBeam, IfcColumn, IfcCurtainWall, IfcDoor, IfcMember, IfcRailing, IfcRamp, IfcRampFlight, IfcWall, IfcSlab, IfcStairFlight, IfcWindow, IfcStair, IfcRoof, IfcPile, IfcFooting, IfcBuildingElementComponent, IfcPlate
Elements that will not directly reference the spatial hierarchy are removed from this category.
IfcDistributionElement / IfcDistributionFlowElement and its subtypes, IfcFlowMovingDevice, IfcFlowSegment, IfcFlowStorageDevice, IfcFlowTerminal, IfcFlowTreatmentDevice
IfcTransportElement / (ELEVATOR, ESCALATOR, MOVINGWALKWAY)
IfcFeatureElement / IfcFeatureElementAddition, IfcFeatureElementSubtraction
IfcElementAssembly / IfcElementAssembly
IfcVirtualElement / IfcVirtualElement
IfcSpace / IfcSpace
IfcGrid / IfcGrid

SEM Family Name

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Spatial Containment

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3-Linkages

SEM Precedent Sequence <Identifies all the sequences where this SEM may be applied, with both before and after links to other SEMS its execution, and which Member(s) to use This may be a large table. Previous SEMS are shown in grey

Scenario (Business purpose) SEMs Used
1. Partial or full project transfer, with or without geometry SEM- 01-01
2. Partial or full project transfer, with site geometry SEM-01-01 SEM 01-02
3. Partial or full project transfer, with or without site geometry and with building geometry
SEM-01-01 SEM-01-02 SEM-01-03
4. Partial or full project transfer, without site geometry, with building geometry
SEM-01-01 SEM-01-03
5. Partial or full project transfer, with or without site geometry, with building geometry and Building Stories
SEM-01-01 SEM-01-02 SEM-01-03 SEM-01-04
SEM-01-01 SEM-01-03 SEM-01-04
6. Partial or full project transfer, with or without site geometry, with building geometry and Building Stories and Spaces (Space not part of the current implementation)
SEM-01-01 SEM-01-02 SEM-01-03 SEM-01-04 SEM-01-05
SEM-01-01 SEM-01-03 SEM-01-04 SEM-01-05
7. Partial or full project transfer, with site geometry, and exterior Spaces
SEM-01-01 SEM-01-02 SEM-01-05

SEM Member Name

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SEM-01-Project- 01

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4 IFC Binding for Member SEM

Version history

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28/4/2011 (CME)

8/6 2011/(CME)

SEM Member binding diagram <biding diagram using flattened entity shapes, for the general case of SEM family; list in title the cases, if any, that this applies to without elaboration>

The SEM Member Project is typically the first SEM created. It lays out the global coordinate system and the basis for the Spatial Containment Hierarchy.

SEM Description:
IfcProject is an entity required in all exchanges, to identify the project and other base information associated with the project. It is singular, by requirement. The IfcProject is used to reference the root of the spatial structure of a building. It has the following assignments:
·  Long name :: project name used for reference purposes
·  RepresentationContext :: reference to IfcGeometricRepresentationContext
·  UnitsInContext :: the set of units used within the project
IfcProject has an associated IfcGeometricRepresentationContext that objects within the project reference. GeometricRepresentationContext defines the following items:
·  CoordinateSpaceDimension :: defines the maximum tolerance distance between two points that are assumed to be the same;
·  WorldCoordinateSystem :: most often (0.,0.,0.), using one of fcAxis2Placement3D for three-D, or IfcAxis2Placement2D for two-D.
·  True North direction :: provided as angle relative to the coordinate origin and orientation. Default is y-axis
SEM Member Methods <Identifies the Methods needed to insert a Member of this SEM Family into the existing SEM structure. Some may be optional, other always apply>
1.  The Project is the first Spatial Configuration Member. It must be assigned a name in the IfcProject.Name. It carries the default units to be applied for the project in Project.UnitsInContext.
2.  A Project, if it includes geometry, must also reference from RepresentationContexts one or more GeomtetricRepresentationContexts. It specifies the world coordinate system, TRUE NORTH, if not the y-axis of the coordinate system, and optionally precision.

SEM Member Name

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SEM-01-Site-02

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5 IFC Binding for Member SEM

Version history

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28/4/2011 (CME)

8/6 2011 (CME)

SEM Member binding diagram biding diagram using flattened entity shapes, for the general case of SEM family; list in title the cases, if any, that this applies to without elaboration

The reference below Project may be Site or Building. Site is optional within a Project,if the project consists of a single Building. IfcSite defines the spatial structure of one or more buildings. The spatial structure elements are linked together by using the objectified relationship IfcRelAggregates (see diagram) . The IfcSite references spatial elements by its inverse relationships. All objects not within the Building level should be assigned to the Site level of the hierarchy. These are typically terrain and site planning model data. These are assigned using IfcRelContainedInSpatialStructure (see BuildingElement).

SEM Description:
A Site plays an important role in terms of spatial coordinate coordination. The IfcLocalPlacement.PlacementRelTo relation can take 3 types of value:
1.  Reference the Project coordinate system defining a Project base coordinate system relative to the context defined by Geometric RepresentationContext.
2.  If the Project coordinate system is not to be the Site reference, then PlacementRelTo is left blank to indicate this site’s origin is the global coordinate system
SEM Methods <Identifies the Methods needed to insert a Member of this SEM Family into the existing SEM structure. Some may be optional, other always apply>
The Spatial Configuration Hierarchy consists of one instance for each element instance in the hierarchy: one project (always), one for each Site in the project, one or more Buildings for each Site; there will be optionally one or more BuildingStorey for each Building. (Spaces are defined as another level in the Spatial Containment Hierarchy.)
1.  Each Spatial Configuration Hierarchy entity is to reference the next higher level in the hierarchy that are part of, as a logical relationship. These should be assigned as encountered.
The qualification of COMPLEX or PARTIAL Spatial Containment Entities should be ignored at this time.
2.  LocalPlacement reference is made to the next higher level in the hierarchy – Prject- consistent with the logical placement.
SEM Member Name / SEM-01-Building-03 / 6 IFC Binding for Member SEM
Version history / 28/4/2011 (CME)
8/6 2011 (CME)
SEM Member binding diagram <biding diagram using flattened entity shapes, for the general case of SEM family; list in title the cases, if any, that this applies to without elaboration>
Building provides a basic element within the spatial structure hierarchy for the components of a building within a Project. If Sites are specified, a Building is associated to a Site. Multiple Buildings may be part of the same Site, in a one-to-many relationship. If a Project consists of a single Building it may optionally directly reference the Project and define the Global coordinate system for the Project.
(NOT IMPLEMENTED) In some cases, a Building may be so large and complex that it is partitioned into PARTIAL Buildings. In these cases a Building. COMPLEX provides for a collection of PARTIAL Buildings (see spatial Containment Overview). A building can also be decomposed in (vertical) parts, where each part defines a PARTIAL Building.
Elements not within the Building should be assigned to the Site level of the hierarchy; these often include parking, pahways and other exterior space uses and construction.. These are assigned using IfcRelContainedInSpatialStructure (see BuildingElement).

One or more Building entities reference the Site or Project they are part of, as a logical relationship. Each is added as encountered. (IGNORE THIS ASPECT) If a Building includes multiple other Buildings, where one Building is a “master” for the others, these are logically organized as the “master”Building being COMPLEX and the others PARTIAL. This is their logical relationship.
A Building also plays an important role in terms of spatial coordinate coordination. The IfcLocalPlacement.PlacementRelTo relation can take 3 types of value:
1. Reference the Site coordinate system when one or more buildings are to be spatially related through a Site base coordinate.
2. If the Site coordinate system is not to be the Building reference, then PlacementRelTo is left blank to indicate this Building’s origin is the global coordinate system. This ESPACIALLY applies when there is only one Building instance or no Site
All other Building attributes are optional and should follow the IFC documentation guidelines.
SEM Methods <Identifies the Methods needed to insert a Member of this SEM Family into the existing SEM structure. Some may be optional, other always apply>
The Spatial Configuration Hierarchy consists of one instance for each element instance in the hierarchy: one project (always), one for each Site in the project (optional), one or more Buildings for each Site; there will be optionally one or more BuildingStory for each Building; Spaces are optional defined as another level in the Spatial Containment Hierarchy.
Each Spatial Configuration Hierarchy entity is to reference the next higher level in the hierarchy that are part of, as a logical relationship. These should be assigned as encountered.
The qualification of COMPLEX or PARTIAL Spatial Containment Entities should be ignored at this time.
SEM Member Name / SEM-01-BuildingStory-04 / 7 IFC Binding for Member SEM
Version history / 28/4/2011 (CME)
8/6 2011 (CME)
SEM Member binding diagram <biding diagram using flattened entity shapes, for the general case of SEM family; list in title the cases, if any, that this applies to without elaboration>
BuildingStory provides a basic spatial classification within the spatial structure hierarchy for the components of a Building. BuildingStory is only defined if there is a Building. A BuildingStory has an elevation, defining the approximate height relative to others. The heights and thus the Storys are ordered. Building Story is considered the primary receiver of Spaces.
Some structurally oriented models , on the other hand, do not use Story and allocate all slabs, beams and columns to the Building in terms of spatial containment (and also coordinate system placement). A Building typically includes multiple, in a one-to-many relationship.(Ignore the following option) In some cases, a Story may be so large and complex that it is partitioned into PARTIAL Storys. In these cases a BuildingStory.COMPLEX provides for a collection of PARTIAL Storys (see spatial Containment Overview).
Objects not within the Building Story level should be assigned to the Building level of the hierarchy; these often include such multi-story objects as stairways, columns and curtainwalls. These are assigned using IfcRelContainedInSpatialStructure.

One or more Building entities reference the Site or Project they are part of, as a logical relationship. Each is added as encountered. (IGNORE THIS ASPECT) If a Building includes multiple other Buildings, where one Building is a “master” for the others, these are logically organized as the “master”Building being COMPLEX and the others PARTIAL. This is their logical relationship.
A Building also plays an important role in terms of spatial coordinate coordination. The IfcLocalPlacement.PlacementRelTo relation can take 3 types of value:
1. Reference the Site coordinate system when one or more buildings are to be spatially related through a Site base coordinate.