IMPORT & EXPORT FORMATS EXPLAINED
Some formats can be put in Revit as stand alone objects (DWG, DXF, DGN, SAT, SKP), others are converted into Revit objects and saved as a Revit file (ADSK, FBX, IFC).
All formats have problems of various types. The more complex the model being exported or imported the greater the likelyhood of problems and inaccuracies.
Always cut back complexity to the minimum required before exporting or importing.
Test workflows before committing to them.
Use the most suited format for the software being imported into. This may mean within a workflow exchange the export format from Revit may be different from the import file format provided (e.g. Revit export=DWG, Import recieved back=IFC).
ADSK
This format is touted by AutoDesk as their 'standard' data exchange format for components.
It contains 3D geometric data plus other schedulable descriptive data.
Currently it is primarily designed to be used by AutoDesk Inventor.
IMPORTING
Use for:
Components made in Inventor.
Comments:
You do not import an ADSK file, you open it with Revit.
Opening or loading an ADSK file automatically creates a family from the category that is based on the OmniClass assignment made on export in the authoring software.
Once opened in Revit you can save the ADSK file as a Revit family file.
You can not open an ADSK file created using Revit's own ADSK export.
EXPORTING
Use for:
Sending files to Civil Engineers using AutoDesk Civil 3D.
Comments:
You can only export a ADSK file as a 'Building Site' exchange file, not a component (i.e. family).
Revit exported ADSK files are designed for importing into AutoDesk Civil 3D, and may not work with other softwares.
The export needs a valid Gross Area plan to be in existance. If one is not Revit asks if you want to create one. After creating it you will need to start the export process again.
DWF & DWFx
This is an 'electronic paper' format like PDF.
DWF is an older proprietory format, DWFx is an open source version. Both are by AutoDesk.
You can export sheet views to create drawing sets; as individual files, or as a combined sheet single file set.
You can also export 3D views. These views become a dynamic 3D model in DWF viewers that can be rotated, cut, and have categories turned off and on.
IMPORTING
Use for:
2D sheet views only that have been marked up in AutoDesk Design Review.
Comments:
You can only import marked-up DWF & DWFx files. If there are no markups it imports nothing.
It will only import to sheet views.
You can not import a 3D DWF or DWFx.
EXPORTING
Use for:
Issuing uneditable drawings that can be marked up in AutoDesk Design Review.
Issuing 3D models that can interrogated, but not altered.
For importing into some clash detection softwares (like Naviworks).
Comments:
You export a DWF or DWFx (not print like PDFs).
Although the export interface is quite different to the print interface, functionally they do the same thing. You have access to Print Sets and Print Settings.
The viewer - AutoDesk Design Review - is free from the AutoDesk web site. This free version allows mark-ups unlike Adobe's free PDF viewer. 3D views can also be marked up.
Recipients of 3D DWF files require a reasonably powerful (i.e. less than 3 years old) computer to view and manipulate the file.
DWG, DXF & DGN
DWG is AutoCAD's format. Also used by AutoCAD based products like AutoCAD MEP and Civil 3D.
DXF is DWG in an open source exchange format.
DGN is Bentley's Microstation, Triforma, Bentley Architecture format.
They can be 'flat', i.e. only in 2D, or made of 3D objects.
IMPORTING
Use for:
Backgrounds.
Survey information.
2D details when creating those details from scratch in Revit would take longer.
Placing contextual elements when you don't have a Revit version, such as trees, people, etc.
Comments:
Backgrounds:
Link into appropriate views only (always tick Current View only).
Always bring in Center to Center NEVER Origin to Origin. CAD usually have insert points hundreds of kilometers away.
Do NOT explode.
2D Details:
Do NOT import or link into a Revit project file.
Import the DWG into a new Detail Component Family file, explode it, clean up and make changes.
Load the new family into the project file.
Contextural Elements:
Do NOT import or link directly into a Revit project file.
Import the DWG into a new Family file of an appropriate cuttable category (NOT Entourage, Furniture, Plants Plumbing). If you use Conceptual Massing it will behave like a Mass in your project. Use Generic Model if nothing is suitable.
Do NOT explode a 3D DWG import. Doing so causes it to disappear.
Load the new family into the project file.
If you imported a 3D DWG file directly into a project file it will not be cut by sections, they display as an elevation in section views. However they will be cut by a 3D scope box in a 3D view.
EXPORTING
Use for:
Providing backgrounds to consultants using AutoCAD products.
Comments:
The process to export sheets and views as DWGs is similar to exporting DWF files (which is similar to printing).
3D objects can be exported as polymeshes or ACIS solids.
Not all software can read ACIS solid files so polymesh files are a safer export format.
DWG probably produces the most accurate export in most cases.
FBX
This format is designed to exchange files used in gaming and animation.
In Revit it is provided to export completed models to 3D Studio Max for rendering.
IMPORTING
Use for:
Not possible to import an FBX file.
Comments:
EXPORTING
Use for:
Sending Revit models to 3D Studio Max or Maya for rendering, animating, creating game scenery.
Comments:
Can crash Revit sometimes.
Takes materials, lights and camera settings of view exported. If you have multiple views each one will need to be exported.
gbXML
This format is designed to feed data into energy analysis programs. Originally specifically for a Californian government web site.
It exports rooms and other energy related data rather than physical geometry.
IMPORTING
Use for:
Not possible to import a gbXML file.
Comments:
EXPORTING
Use for:
Sending data to energy analysis software.
Comments:
The gbXML systems makes a lot of assumptions, all based on USA norms and expectations. This makes it pretty useless for energy analysis anywhere but the USA.
IFC
The international open source format for transfer of BIM information.
In theory IFC maintains the BIM functionality of objects when transferred between softwares.
AutoDesk products are notorious for being the worst at creating and importing IFC files.
IMPORTING
Use for:
Backgrounds.
Comments:
You do not import an IFC file, you open it with Revit. You can then save it as a Revit file. If you link an IFC file Revit creates a Revit linked file from the IFC file.
Revit converts what it can into Revit categories, everything else into a non-standard Generic Models category. This category has only Identity Data and Phasing parameters.
It only imports objects, not annotation or sheets.
Curves are turned into segments of flat faces.
It is rare for every object to be imported unscathed. Problems particularly occur with voids and openings. Often objects will not display properly, with stray extended lines (possibly relocated sweep paths).
Because of this the accuracy of the import should not be relied on.
IFC files become Revit files objects so will be cut by sections (unlike DWG or SAT files).
EXPORTING
Use for:
Providing backgrounds to consultants.
For import into some clash detection and analysis softwares.
Comments:
The objects you want to export in an IFC file must exist in the Revit file you are doing it from. You can not export objects in a linked file.
Revit categories are mapped to standard IFC categories. This can be controlled by setting IFC export options (found at the bottom of the list in the export menu). In theory Revit categories and sub-categories can be excluded from the export, but when I tried it didn't work.
Not all IFC parameters are in Revit files by default. They can be imported by copying and pasting a schedule from an AutoDesk supplied Revit file. Sometimes doing this causes Revit to crash.
Tick Split walls and columns by levels when exporting. This will add all the projects levels.
Also tick Current view only to restrict objects being exported.
Don't export Light Fixtures or Electrical Fixtures if possible (turn them off in the view before exporting), as the light source mass gets exported as an object.
SAT
An ACIS solids file format. ACIS is a standard for describing the geometry of solid objects, as opposed to mesh objects made of infinitely thin planes.
IMPORTING
Use for:
Simple objects created in Rhino or AutoCAD.
It is the preferred export method from Rhino - Rhino changes the shape of objects when converting to a mesh.
Comments:
Do NOT import or link directly into a Revit project file.
Import the SAT into a new Family file of an appropriate cuttable category (NOT Entourage, Furniture, Plants Plumbing). If you use Conceptual Massing it will behave like a Mass in your project. Use Generic Model if nothing is suitable.
Link SATs used as backgrounds, use import for individual SAT elements.
You can explode SAT imports into Revit lines, but only if they are 2D, which is pointless because all SAT objects are 3D. So exploding a 3D SAT import causes it to disappear.
SAT files imported directly into a Revit project file will not be cut by sections, they display as an elevation in section views, but imported SAT files can be cut by a 3D scope box.
EXPORTING
Use for:
Putting Revit models into Rhino.
Comments:
SAT files can be extremely large.
SAT files contain no information about materials.
SKP
This is the format of Google SketchUp, a 3D drawing program.
There is a free version of SketchUp, and many component libraries.
Sketchup uses infinitely thin planes to model, and mimics curves using segmented flat planes.
IMPORTING
Use for:
3D backgrounds.
Placing contextual elements when you don't have a Revit version, such as trees, people, etc.
Comments:
Do NOT import or link directly into a Revit project file.
Import the SKP into a new Family file of an appropriate cuttable category (NOT Entourage, Furniture, Plants Plumbing). If you use Conceptual Massing is will behave like a Mass in your project. Use Generic Model if nothing is suitable.
Do NOT explode a SKP import. Doing so causes all 3D objects to disappear.
Load the new family into the project file.
If you imported a SKP file directly into a project file it will not be cut by sections, they display as an elevation in section views. However they will be cut by a 3D scope box in a 3D view.
EXPORTING
Use for:
It is not possible to export SKP files from Revit.
Comments: