Revit BHoM conversion - BHoM/Revit_Toolkit GitHub Wiki

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Revit_Toolkit provides bi-directional conversion between Revit and BHoM. This conversion is an integral part of Push and Pull Adapter actions - besides simply translating Revit elements into BHoM objects, it ensures correctness of the units and, in general, allows representing Revit objects outside of Revit context.

Sections below explain the practicalities of that process, while its code mechanics is discussed in Push details and Pull details sections.

Due to multidisciplinarity of both BHoM and Revit, conversion from Revit is not always a singular problem: some elements can be converted into multiple BHoM types, depending on user's discipline preference set in RevitPullConfig. Table below contains a matrix of possible converts organized by discipline.

Revit Category	Revit Type	BHoM Physical	BHoM Structural	BHoM Envinronments	BHoM Architecture	BHoM Facade
Grids	Autodesk.Revit.DB.Grid	BH.oM.Geometry.SettingOut.Grid	BH.oM.Geometry.SettingOut.Grid	BH.oM.Geometry.SettingOut.Grid	BH.oM.Geometry.SettingOut.Grid	BH.oM.Geometry.SettingOut.Grid
Levels	Autodesk.Revit.DB.Level	BH.oM.Geometry.SettingOut.Level	BH.oM.Geometry.SettingOut.Level	BH.oM.Geometry.SettingOut.Level	BH.oM.Geometry.SettingOut.Level	BH.oM.Geometry.SettingOut.Level
Walls	Autodesk.Revit.DB.Wall	BH.oM.Physical.Elements.Wall	BH.oM.Structure.Elements.Panel	BH.oM.Environment.Elements.Panel	BH.oM.Physical.Elements.Wall	BH.oM.Facade.Elements.CurtainWall
Floors / Foundation Slabs	Autodesk.Revit.DB.Floor	BH.oM.Physical.Elements.Floor	BH.oM.Structure.Elements.Panel	BH.oM.Environment.Elements.Panel	BH.oM.Physical.Elements.Floor	BH.oM.Physical.Elements.Floor
Roofs	Autodesk.Revit.DB.RoofBase	BH.oM.Physical.Elements.Roof	BH.oM.Structure.Elements.Panel	BH.oM.Environment.Elements.Panel	BH.oM.Physical.Elements.Roof	BH.oM.Physical.Elements.Roof
Structural Columns	Autodesk.Revit.DB.FamilyInstance	BH.oM.Physical.Elements.Column	List<BH.oM.Structure.Elements.Bar>		BH.oM.Physical.Elements.Column
Structural Framing	Autodesk.Revit.DB.FamilyInstance	BH.oM.Physical.Elements.Beam / BH.oM.Physical.Elements.Bracing	List<BH.oM.Structure.Elements.Bar>		BH.oM.Physical.Elements.Beam / BH.oM.Physical.Elements.Bracing
Windows	Autodesk.Revit.DB.FamilyInstance	BH.oM.Physical.Elements.Window		BH.oM.Physical.Elements.Window	BH.oM.Physical.Elements.Window	BH.oM.Facade.Elements.Opening
Doors	Autodesk.Revit.DB.FamilyInstance	BH.oM.Physical.Elements.Door		BH.oM.Physical.Elements.Door	BH.oM.Physical.Elements.Door	BH.oM.Facade.Elements.Opening
Curtain Panels	Autodesk.Revit.DB.Panel	BH.oM.Physical.Elements.Window		BH.oM.Physical.Elements.Window	BH.oM.Physical.Elements.Window	BH.oM.Facade.Elements.Opening
Ceilings	Autodesk.Revit.DB.Ceiling	BH.oM.Architecture.Elements.Ceiling		BH.oM.Environment.Elements.Panel	BH.oM.Architecture.Elements.Ceiling	BH.oM.Architecture.Elements.Ceiling
Spaces / Rooms	Autodesk.Revit.DB.SpatialElement	BHoM.Architecture.Elements.Room		BH.oM.Environment.Elements.Space	BHoM.Architecture.Elements.Room	BHoM.Architecture.Elements.Room
Project Information	Autodesk.Revit.DB.ProjectInfo			BH.oM.Environment.Elements.Building
Analytical Surfaces	Autodesk.Revit.DB.Analysis.EnergyAnalysisSpace	BH.oM.Environment.Elements.Space		BH.oM.Environment.Elements.Space	BH.oM.Environment.Elements.Space	BH.oM.Environment.Elements.Space
Interior, Exterior, Shades	Autodesk.Revit.DB.Analysis.EnergyAnalysisSurface	BH.oM.Environment.Elements.Panel		BH.oM.Environment.Elements.Panel	BH.oM.Environment.Elements.Panel	BH.oM.Environment.Elements.Panel
Opening	Autodesk.Revit.DB.Analysis.EnergyAnalysisOpening	BH.oM.Environment.Elements.Panel		BH.oM.Environment.Elements.Panel	BH.oM.Environment.Elements.Panel	BH.oM.Environment.Elements.Panel
Families	Autodesk.Revit.DB.Family	BH.oM.Adapters.Revit.Elements.Family	BH.oM.Adapters.Revit.Elements.Family	BH.oM.Adapters.Revit.Elements.Family	BH.oM.Adapters.Revit.Elements.Family	BH.oM.Adapters.Revit.Elements.Family
Materials	Autodesk.Revit.DB.Material	BH.oM.Physical.Materials.Material	BH.oM.Structure.MaterialFragments.IMaterialFragment	BH.oM.Environment.MaterialFragments.SolidMaterial	BH.oM.Physical.Materials.Material	BH.oM.Physical.Materials.Material
Sheets	Autodesk.Revit.DB.Sheet	BH.oM.Adapters.Revit.Elements.ViewSheet	BH.oM.Adapters.Revit.Elements.ViewSheet	BH.oM.Adapters.Revit.Elements.ViewSheet	BH.oM.Adapters.Revit.Elements.ViewSheet	BH.oM.Adapters.Revit.Elements.ViewSheet
Viewports	Autodesk.Revit.DB.Viewport	BH.oM.Adapters.Revit.Elements.Viewport	BH.oM.Adapters.Revit.Elements.Viewport	BH.oM.Adapters.Revit.Elements.Viewport	BH.oM.Adapters.Revit.Elements.Viewport	BH.oM.Adapters.Revit.Elements.Viewport
Views (Plan)	Autodesk.Revit.DB.ViewPlan	BH.oM.Adapters.Revit.Elements.ViewPlan	BH.oM.Adapters.Revit.Elements.ViewPlan	BH.oM.Adapters.Revit.Elements.ViewPlan	BH.oM.Adapters.Revit.Elements.ViewPlan	BH.oM.Adapters.Revit.Elements.ViewPlan
Ducts	Autodesk.Revit.DB.Mechanical.Duct	BH.oM.MEP.System.Duct		BH.oM.MEP.System.Duct	BH.oM.MEP.System.Duct
Pipes	Autodesk.Revit.DB.Plumbing.Pipe	BH.oM.MEP.System.Pipe		BH.oM.MEP.System.Pipe	BH.oM.MEP.System.Pipe
Wires	Autodesk.Revit.DB.Electrical.Wire	BH.oM.MEP.System.Wire		BH.oM.MEP.System.Wire	BH.oM.MEP.System.Wire
Cable Trays	Autodesk.Revit.DB.Electrical.CableTray	BH.oM.MEP.System.CableTray		BH.oM.MEP.System.CableTray	BH.oM.MEP.System.CableTray
Fittings	Autodesk.Revit.DB.FamilyInstance	BH.oM.MEP.System.Fittings.Fitting		BH.oM.MEP.System.Fittings.Fitting	BH.oM.MEP.System.Fittings.Fitting
Builders Work Openings	Autodesk.Revit.DB.FamilyInstance	BH.oM.Architecture.BuildersWork.Opening			BH.oM.Architecture.BuildersWork.Opening
Mullions	Autodesk.Revit.DB.Mullion					BH.oM.Facade.Elements.FrameEdge

In case of conversion to structural BHoM types, Revit element is first queried for its analytical model, and its physical representation is used only if the former does not exist.

If a Revit element is requested to be pulled and there is no explicit convert method for its type and given discipline, it will get converted into a ModelInstance, DraftingInstance or InstanceProperties. If that fails too, a BHoMObject with only basic information is returned. The conversion procedure is shown in the flowchart below.

Every time a Revit element is converted, its element type is converted along it. The information about the latter can be stored in 2 ways:

• in defining BHoM property, e.g. Construction of Wall - the characteristics of the element type as well as its parameters are converted and attached to this property (Wall.Construction contains the information about the Revit wall type and its parameters)
• in RevitTypeFragment attached to the BHoM object representing the element (in case the BHoM object does not have a defining property that could correspond to the Revit element type, e.g. Architecture.Room) - only parameters of the element type are converted and stored in the fragment to allow querying and updating them

To find out where is the Revit element type information stored inside a particular BHoM object, it is recommended to call GetRevitElementType.

Conversion from BHoM to Revit is rather simple: the BHoM object is coming through BH.Revit.Engine.Core.Convert.IToRevit, which points it to the appropriate ToRevit method that creates an element in the active Revit document. Table below contains a list of BHoM types that can be converted, together with their relevant Revit types. As a general rule, analytical objects (of types that belong to namespaces BH.oM.Structure or BH.oM.Environment) are not allowed to be pushed to Revit - their physical equivalents (objects of types from BH.oM.Physical namespace) should be used instead. So far, the only exception from that rule is BH.oM.Environment.Elements.Space.

BHoM type	Revit Category	Revit Type
BH.oM.Geometry.SettingOut.Grid	Grids	Autodesk.Revit.DB.Grid
BH.oM.Geometry.SettingOut.Level	Levels	Autodesk.Revit.DB.Level
BH.oM.Physical.Elements.Wall	Walls	Autodesk.Revit.DB.Wall
BH.oM.Physical.Elements.Floor	Floors / Structural Foundations	Autodesk.Revit.DB.Floor
BH.oM.Physical.Elements.Roof	Roofs	Autodesk.Revit.DB.RoofBase
BH.oM.Physical.Elements.Column	Structural Columns	Autodesk.Revit.DB.FamilyInstance
BH.oM.Physical.Elements.Beam	Structural Framing	Autodesk.Revit.DB.FamilyInstance
BH.oM.Physical.Reinforcement.IReinforcingBar	Structural Rebar	Autodesk.Revit.DB.Structure.Rebar
BH.oM.Environment.Elements.Space	Spaces	Autodesk.Revit.DB.Mechanical.Space
BH.oM.Adapters.Revit.Elements.ViewPlan	Views (Plan)	Autodesk.Revit.DB.ViewPlan
BH.oM.Adapters.Revit.Elements.Viewport	Viewports	Autodesk.Revit.DB.Viewport
BH.oM.Adapters.Revit.Elements.ViewSheet	Sheets	Autodesk.Revit.DB.Sheet
BH.oM.MEP.System.Duct	Ducts	Autodesk.Revit.DB.Mechanical.Duct
BH.oM.MEP.System.Pipe	Pipes	Autodesk.Revit.DB.Plumbing.Pipe
BH.oM.MEP.System.CableTray	Cable Trays	Autodesk.Revit.DB.Electrical.CableTray
BH.oM.Adapters.Revit.Parameters.ParameterDefinition	-	Autodesk.Revit.DB.ParameterElement
BH.oM.Adapters.Revit.Elements.Family	-	Autodesk.Revit.DB.Family
BH.oM.Adapters.Revit.Elements.InstanceProperties	-	Autodesk.Revit.DB.ElementType

Conversion of BHoM object properties such as Construction or FramingProperties to Revit is currently not supported - Revit element type is applied based on name matching with defining property of a BHoM object (e.g. Construction of a wall or Property of a beam). Therefore, to create a Revit element of given family type, one needs to set BHoM object's property name to same value. Example of Push using this approach is available in examples.

A limited ability to create Revit types is provided by BH.oM.Adapters.Revit.ClonedType object - pushing it creates a clone of an existing Revit element type with a new name, which then can be updated freely.

The last two rows of the table, Family and InstanceProperties, correspond to an action of loading the families or chosen types to the model - this works only in combination with FamilyLibrary.

It is possible to push almost any Revit element using ModelInstance and DraftingInstance, explained in more detail below.

There are three powerful generic types in Revit_Adapter that can wrap any Revit element. These are:

• ModelInstance - any Revit view independent element that has Location property
• DraftingInstance - any Revit view dependent element that has Location property
• InstanceProperties - any Revit ElementType or GraphicsStyle

The above types can be used on Push to create Revit elements that do not have a correspondent BHoM type, e.g. mechanical equipment, generic annotations or filled regions - examples of these can be found in examples.

The usage of ModelInstance, DraftingInstance and InstanceProperties on Pull has been explained in Conversion from Revit paragraph.

The table below presents geometry conversion methods offered by Revit_Toolkit.

Revit type	Supported conversion direction	BHoM type
Autodesk.Revit.DB.XYZ	< - >	BH.oM.Geometry.Point
Autodesk.Revit.DB.XYZ	< - >	BH.oM.Geometry.Vector
Autodesk.Revit.DB.Plane	< - >	BH.oM.Geometry.CoordinateSystem.Cartesian
Autodesk.Revit.DB.Line	< - >	BH.oM.Geometry.Line
Autodesk.Revit.DB.Arc	< - >	BH.oM.Geometry.Arc / BH.oM.Geometry.Circle
Autodesk.Revit.DB.Ellipse	< - >	BH.oM.Geometry.Ellipse
Autodesk.Revit.DB.NurbSpline	< - >	BH.oM.Geometry.NurbsCurve
Autodesk.Revit.DB.HermiteSpline	- >	BH.oM.Geometry.NurbsCurve
Autodesk.Revit.DB.Analysis.Polyloop	- >	BH.oM.Geometry.Polyline
Autodesk.Revit.DB.PolyLine	- >	BH.oM.Geometry.Polyline
Autodesk.Revit.DB.CurveLoop	< - >	BH.oM.Geometry.PolyCurve
Autodesk.Revit.DB.Solid	< -	BH.oM.Geometry.ISurface
Autodesk.Revit.DB.Solid	< -	BH.oM.Geometry.BoundaryRepresentation

In a special case where Revit requires an unbound curve (e.g. in case of floor outlines) closed BHoM curves are split in half to create a continuous loop consisting of two unbound Revit curves.

It is worth noting that pushing BHoM geometries directly to Revit is not allowed - they always need to be wrapped into some type of object (if are meant to be pushed as primitives, ModelInstance or DraftingInstance is recommended. Similarly, on pull, each geometrical Revit element will be wrapped into a non-primitive BHoM type.

Revit element parameters can be pulled from and pushed to Revit together with an element. That is possible thanks to the fragment-based scheme explained in Handling of Parameters section. Besides that, the information about identity of Revit elements correspondent to the BHoM objects is stored in RevitIdentifiers fragment as explained in BHoM vs Revit identity.

On top of the above, it is possible to create an entirely new parameter definition in Revit: either a project parameter or shared one. This is done by pushing the BH.oM.Adapters.Revit.Parameters.ParameterDefinition object.

It is possible to pull a material take-off of any Revit element on Pull. It can be achieved by using RevitPullConfig with PullMaterialTakeOff property set to true. Once that is done, RevitMaterialTakeOff fragment will be added to each pulled BHoM object, which can then be converted into an ExplicitBulk using MaterialTakeoff query.

It is likely that the adapter will generate warnings on converts. This is related to the fact that each Revit object consists of a multitude of information that often cannot be translated to BHoM one to one. It is important to read warning messages as they usually explain what issue has been found.

Error messages, on the other hand, usually mean that a serious issue occurred on convert: either the object has not been converted due to an error in the method, or the conversion method simply does not exist. Same as with warnings, error messages should provide detailed information about the problem.