by Dennis Collin
Revit can create massing forms which are useful in initial massing studies. These tools are complemented with Autodesk’s companion products such as FormIt and the new Forma products. However, what about users who still wish to do concept models with other products such as SketchUp and Rhino? This is particularly the case when more organic forms are required.
Fig 1. An accurate free form roof element modelled in Rhino.
Despite being modelled in third party solutions, geometry showing these organic forms can still be imported into Revit. These forms can be sliced for quick floor areas or have complex walls, curtain systems or roofs assigned to these surfaces. Or have some complex structural framing formed using scripting tools like Dynamo.
Fig 2. Most modelling software have close hole or patching commands to make watertight geometry.
To achieve full functionality the imported geometry needs to be a watertight volume i.e. the solid surface edges need to have no gaps. Most solid modelling packages do have a cap holes function which should remedy most leaks. I would also recommend that elements are correctly scaled with suitable units assigned in the authoring product. The element should also be close to the respective product’s origin location i.e. either centred or the origin located on a suitable geometric reference point, such as a corner or edge centre.
Fig 3. Revit families can import many formats including Rhino (3DM) and SketchUp files (SKP)
To make geometry into a usable Revit mass, the geometry needs to be imported into a Revit Mass Family. This can be done by choosing a new component family and going to the Import CAD data, choosing the appropriate file format. In recent years this also includes Rhino 3DM and SketchUp SKP files.
Fig 4. Depending on the Revit version used, other formats may be available.
Once confirmed, the geometry should appear in the family component. This component should be appropriately named and saved in a suitable location.
Fig 5. Open volumes are treated as surface elements with reduced functionality.
The key test is the loading of the component into a Revit Project. By default, a Revit mass family requires either a face or a level as a host. If Revit reports the mass as a mesh, the reason will be that the incoming geometry has leaks or gaps in the defining volume. Whilst surfaces can be utilised to form façade elements like roofs and walls , the mass cannot be used for mass slicing and initial floor area schedules. If this feature is required, corrective action needs to be taken on the original geometry. This is best done with the original software if possible.
Fig 6. Using a custom Mass family to create mass floor slices.
For quick presentation, materials can be assigned to massing components, but typically, mass elements display as transparent elements.
Fig 7. Provided the geometry is in a mass family, building elements can be added by face.
If required, these elements can be sliced with intersecting level elements, where schedules can be performed. In addition, organic wall, roof and curtain system forms can be created by using the place by face option. These elements are linked to the mass and can update if the host mass changes with an update geometry toggle.
Fig 8. Walls, Floors, Roofs, and Curtain Systems can be applied to conceptual massing families. These can be scheduled if required (Below)