#### 5.4.3.8 IfcGrid

| Grille
| Raster

IfcGrid ia a planar design grid defined in 3D space used as an aid in locating structural and design elements. The position of the grid (ObjectPlacement) is defined by a 3D coordinate system (and thereby the design grid can be used in plan, section or in any position relative to the world coordinate system). The position can be relative to the object placement of other products or grids. The XY plane of the 3D coordinate system is used to place the grid axes, which are 2D curves (for example, line, circle, arc, polyline).

The inherited attributes Name and Description can be used to define a descriptive name of the grid and to indicate the grid's purpose. A grid is defined by (normally) two, or (in case of a triangular grid) three lists of grid axes. The following figures shows some examples.

A grid may support a rectangular layout as shown in Figure 78, a radial layout as shown in Figure 79, or a triangular layout as shown in Figure 80.

> NOTE The PredefinedType denotes the type of grid that is represented by IfcGrid. The instantiation of IfcGridAxis's has to agree to the PredefinedType, if provided.

> NOTE The grid axes, defined within the design grid, are those elements to which project objects will be placed relatively using the IfcGridPlacement.

Figure 78 — Grid rectangular layout | Figure 79 — Grid radial layout | Figure 80 — Grid triangular layout

> HISTORY New entity in IFC1.0.

> IFC4 CHANGE The attribute PredefinedType has been added at the end of the attribute list.

Informal Propositions:

Grid axes, which are referenced in different lists of axes (UAxes, VAxes, WAxes) shall not be parallel. Grid axes should be defined such as there are no two grid axes which intersect twice (see Figure 189). NOTE Left side: ambiguous intersections A1 and A2, a grid containing such grid axes is not a valid design grid; Right side: the conflict can be resolved by splitting one grid axis in a way, such as no ambiguous intersections exist. | Figure 81 — Grid intersections

## Electrical System Design

Instance diagram

Identity

The Identity concept applies to this entity.

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  | R |  |  | R | R | R
Export |  |  |  |  |  |  |  | R |  |  | R | R | R

Spatial Containment

The Spatial Containment concept applies to this entity.

Placement

The Placement concept applies to this entity.

The local placement for IfcGrid is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.

- The PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of the same IfcSpatialStructureElement, which is used in the ContainedInStructure inverse attribute, or to a spatial structure element at a higher level, referenced by that.
- If the relative placement is not used, the absolute placement is defined within the world coordinate system.

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  | R |  |  | R | R | R
Export |  |  |  |  |  |  |  | R |  |  | R | R | R

Grid

The Grid concept applies to this entity as shown in Table 24.

GridType | UCurve | VCurve | Description
--- | --- | --- | ---
RECTANGULAR | IfcLine | IfcLine | For ceiling grids, lines along each axis are perpendicular and have regular offsets. Standard sizes in U.S. are 2x2 feet and 2x4 feet.
Table 24 — IfcGrid Grid

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  | R |  |  | R | R | R
Export |  |  |  |  |  |  |  | R |  |  | R | R | R

XSD Specification:

<xs:element name="IfcGrid" type="ifc:IfcGrid" substitutionGroup="ifc:IfcProduct" nillable="true"/>
<xs:complexType name="IfcGrid">
<xs:complexContent>
<xs:extension base="ifc:IfcProduct">
<xs:sequence>
<xs:element name="UAxes">
<xs:complexType>
<xs:sequence>
<xs:element ref="ifc:IfcGridAxis" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute ref="ifc:itemType" fixed="ifc:IfcGridAxis"/>
<xs:attribute ref="ifc:cType" fixed="list-unique"/>
<xs:attribute ref="ifc:arraySize" use="optional"/>
</xs:complexType>
</xs:element>
<xs:element name="VAxes">
<xs:complexType>
<xs:sequence>
<xs:element ref="ifc:IfcGridAxis" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute ref="ifc:itemType" fixed="ifc:IfcGridAxis"/>
<xs:attribute ref="ifc:cType" fixed="list-unique"/>
<xs:attribute ref="ifc:arraySize" use="optional"/>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="PredefinedType" type="ifc:IfcGridTypeEnum" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcGrid

| SUBTYPE OF (IfcProduct);

UAxes | : | LIST [1:?] OF UNIQUE IfcGridAxis;
VAxes | : | LIST [1:?] OF UNIQUE IfcGridAxis;
WAxes | : | OPTIONAL LIST [1:?] OF UNIQUE IfcStrippedOptional;
PredefinedType | : | OPTIONAL IfcGridTypeEnum;

| INVERSE

ContainedInStructure | : | SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

| WHERE

HasPlacement | : | EXISTS(SELF\IfcProduct.ObjectPlacement);

END_ENTITY;

Attribute Definitions:

UAxes | : | List of grid axes defining the first row of grid lines.
VAxes | : | List of grid axes defining the second row of grid lines.
WAxes | : | List of grid axes defining the third row of grid lines. It may be given in the case of a triangular grid.
PredefinedType | : | Predefined types to define the particular type of the grid. IFC4 CHANGE New attribute.
ContainedInStructure | : | Relationship to a spatial structure element, to which the grid is primarily associated. IFC2x CHANGE The inverse relationship has been added to IfcGrid with upward compatibility

Formal Propositions:

HasPlacement | : | The placement for the grid has to be given.

Inheritance Graph:

ENTITY IfcGrid

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcObjectDefinition

| INVERSE

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 IfcObject

ObjectType | : | OPTIONAL IfcStrippedOptional;

| INVERSE

IsDeclaredBy | : | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares | : | SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy | : | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy | : | SET OF IfcRelDefinesByProperties FOR RelatedObjects;

| ENTITY IfcProduct

ObjectPlacement | : | OPTIONAL IfcObjectPlacement;
Representation | : | OPTIONAL IfcProductRepresentation;

| INVERSE

ReferencedBy | : | SET OF IfcRelAssignsToProduct FOR RelatingProduct;

| ENTITY IfcGrid

UAxes | : | LIST [1:?] OF UNIQUE IfcGridAxis;
VAxes | : | LIST [1:?] OF UNIQUE IfcGridAxis;
WAxes | : | OPTIONAL LIST [1:?] OF UNIQUE IfcStrippedOptional;
PredefinedType | : | OPTIONAL IfcGridTypeEnum;

| INVERSE

ContainedInStructure | : | SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

END_ENTITY;

Link to this page