樓宇智能化IFC的前端設備數(shù)據(jù)描述！
樓宇智能化屬于電氣領域，處于IFC標準中的專業(yè)領域層。在IFC4標準中定義為IfcElectricalDomain。IfcElectricalDomain支持的類型主要有IfcFlowTerminalType(終端設備類型)、IfcFlow SegmentType(終端分段類型)、IfcFlowFittingType(終端燈具類型)、IfcFlowStorageDeviceType(終端存儲設備類型)、IfcFlowControllerType(終端開關類型)、IfcDistributionControlElementType(配電控制類型)和IfcEnergyConversionDeviceType(能量轉換設備類型)。
其中IfcFlowTerminalType定義的實體有Outlet(插座)、LightFixture(燈具)、Lamp(光源)、ElectricAppliance(電器設備)、AudioVisualApplication(音視頻設備)、CommunicationsAppliance(通訊設備)。樓宇智能化中的前端設備主要有攝像機，屬于音視頻設備，因此可以用AudioVisualApplication來表示，下面對樓宇智能化中的前端設備進行基于IFC標準的數(shù)據(jù)描述。
AudioVisualApplication的Express-G圖表示如圖。
AudioVisualApplication的Express描述如下：
ENTITY IfcAudioVisualApplianceType
SUBTYPE OF IfcFlowTerminalType; //IfcAudioVisualApplianceType是IfcFlowTerminalType的子類型
PredefinedType: IfcAudioVisualApplianceTypeEnum;
WHERE //形式限制
CorrectPredefinedType: (PredefinedType <>
IfcAudioVisualApplianceTypeEnum.USERDEFINED) OR((PredefinedType=
IfcAudioVisualApplianceTypeEnum.USERDEFINED) AND EXISTS
(SELF\IfcElementType.ElementType));
END_ENTITY;
AudioVisualApplication屬性間的繼承關系如下：
ENTITY IfcAudioVisualApplianceType
ENTITY IfcRoot
GlobalId: IfcGloballyUniqueId;
OwnerHistory: OPTIONAL IfcOwnerHistory;
Name: OPTIONAL IfcLabel;
Description: OPTIONAL IfcText;//定義
IfcRoot的四個屬性
ENTITY IfcObjectDefinition
INVERSE //反轉屬性，明確定義實體之間“雙向”的一對多或多對多關系
HasAssignments: SET OF IfcRelAssigns FOR RelatedObjects;
Nests: SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy: SET OF IfcRelNests FOR RelatingObject;
HasContext: SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy: SET OF IfcRelAggregates
FOR RelatingObject;
Decomposes: SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations: SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcTypeObject
ApplicableOccurrence: OPTIONAL IfcIdentifier;
HasPropertySets: OPTIONAL SET [1:?]
OF IfcPropertySetDefinition;
INVERSE
Types: SET [0:1] OF IfcRelDefinesByType FOR RelatingType;
ENTITY IfcTypeProduct
RepresentationMaps: OPTIONAL LIST [1:?]
OF
UNIQUE IfcRepresentationMap;
Tag: OPTIONAL IfcLabel;
INVERSE
ReferencedBy: SET OF IfcRelAssignsTo Product FOR RelatingProduct;
ENTITY IfcElementType
ElementType: OPTIONAL IfcLabel;
ENTITY IfcDistributionElementType
ENTITY IfcDistributionFlowElementType
ENTITY IfcFlowTerminalType
ENTITY IfcAudioVisualApplianceType
PredefinedType: IfcAudioVisualAppliance TypeEnum;
END_ENTITY;
