Tips & Tricks

Direct exchange of 3D models between Revit and ARCHICAD

The American ARCHICAD supplyer, BIM6x, has released a free plugin for ARCHICAD, which allows you to import and export files directly to Revit in RVT or RFA format. You can read more about the plugin and download directly from BIM6x's website.

Besides the fact that it quite makes it obvious to open Revit files in ARCHICAD, the new plugin also means that it now also is possible to open Revit files on a Mac…

The plugin is based on Teigha technology from the Open Design Alliance, which also develops the technology behind the DWG translator, which we already know from ARCHICAD. With a little help from GRAPHISOFT, BIM6x has transformed this into a coherent and useful solution in ARCHICAD.

There are 3 import and export options with the smart plugin:

  • Import RFA objects like GDL-0 objects (door, window or object) from RFA files in version 2011-2018
  • Hotlink 3D geometry from RVT files in ARCHICAD from Revit 2011-2018
  • Export the ARCHICAD model as 3D geometry as RVT files to Revit 2017

Let's first look at the export to Revit. As the illustration above shows this is completely painless. There are some different settings that are mainly allows yout to determine which properties to export.

It’s important to note that it’s only geometry that is exported - that is, not drawings - and the objects do not turn into walls, doors, decks, roofs and stairs in Revit, but are only shown as geometry ("in place mass"). If you want to have a wall in ARCHICAD translated into a wall in Revit, you must use IFC. - But the quality of the 3D model is high with correct geometry, as well as surfaces. The image below shows my test model opened in Revit:

Another option is to link RVT files into ARCHICAD, which is also easy, using the same method as when Hotlinked Modules and IFC are linked into the model:

The entire linked model belongs to a layer that allows you to turn the entire linked model on and off with just one click. You can also control whether the floors of the floors must be kept as in the Revit file, or if you want to force them to follow the floor placement of the ARCHICAD project.

In addition, one can also control whether properties and materials must be imported from the Revit file, and in which detail curved building parts must be displayed, so that the model does not become too rough or too heavy to handle. By default, Revit's categories are created as separate layers and with Layer Extension "RVT", so that these layers can easily be distinguished from the rest:

Layers can be controlled by Revit's categories, making it easy to turn object types on and off, since all objects in ARCHICAD are imported as GDL objects. A wall from Revit does not become a wall in ARCHICAD, but "just" an object. If you want to have the building parts to the correct types in ARCHICAD, you must use IFC files rather than RVT files. - But the linked model turns out really nice in ARCHICAD:

Although the 3D model is translated very well, it’s difficult to say the same for the plan view, since all building parts are translated into GDL objects:

However, sections and accomodations work just fine.

The last option is to import Revit Families as GDL objects. Again, it's super easy! As an example, I've downloaded some windows from www.bimobject.com made only for Revit:

The objects are then imported into ARCHICAD, and again there are some options to you have to decide upon as you progress:

It almost goes without saying, and there aren’t many clicks before the window is in the ARCHICAD file directory:

Here you can set very few options, but also see some of the data that is included in the import from Revit. Then just put the window in a wall:

It works fine, but there may be slightly different problems with the geometry, such as a small distance between the window and the wall, which can be difficult to live with. On the plan, the window's icon is also a little poor:

Generally speaking, there are a number of challenges by opening and saving Revit files directly in ARCHICAD. It’s only the 3D model's geometry that is brought over and not the drawings. One can either open and save the entire 3D model, which results in a really nice geometry, but where everything becomes GDL objects in ARCHICAD or "Masses" in Revit - or you can also import Revit Families individually, where windows and doors are categorized correctly, but only partially displayed correctly in the model.

The quality of the exchange is thus greater using IFC or GDL objects specifically developed for ARCHICAD. So this new plugin does not change anything about the fact that cross-disciplinary exchanges should still be the IFC and that manufacturers still need to develop BIM objects for both Revit and ARCHICAD. - But if one day you find that you only have access to the Revit file, then there is now a solution that actually works at a reasonable level.

Some of the benefits of IFC rather than direct translation of Revit files are:

  • Parametric components
  • Objectives that follow the objects
  • Information on constructions, eg. carrying capacity and composite building parts
  • The structure of the building parts, such as. that a window belongs to a wall
  • The ability to filter the contents of the model upon import
  • Control of the model's zero point with the "Survey Point" object
  • Translation of the module network

Another reason for continuing to adhere to the IFC is that Autodesk does not document how their file format works. This means that the Open Design Alliance has tried to develop their own translator until they have found a solution that works. Therefore, the RVT / RFA conversion will always be a version after the latest Revit version, and you won’t be able to guarantee that this will work in the future. Who knows if BIM6x will continue to invest in the development of a Revit translator and whether it remains a free solution? Conversely, it’s also possible that the Open Design Alliance will be better and better at translating Revit files, so that the quality, property data and object types will improve in the future. - Imagine if the drawings can be translated one day, then Sheets in Revit become Layouts in ARCHICAD with all the graphics correctly translated!

So nothing has changed. It is still the IFC that is the current standard for exchange between Revit and ARCHICAD. Manufacturers should still make specific BIM objects for both Revit and ARCHICAD. ARCHICAD is still at thefront of the field when it comes to managing a wide variety of software-specific (proprietary) file formats, such as RVT (Revit), RFA (Revit Families), 3DM (Rhino), SKP (Sketchup), 3DS (3DStudio), Artlantis, Google Earth, DWG (AutoCAD) and DGN (Microstation). ARCHICAD is still one of the very best BIM programs in terms of being able to import and export files in open standards, such as IFC, DXF, PDF, JPEG, TIFF, MGEP, MPEG4, PNG and GIF. Not to mention that ARCHICAD can save to previous versions of its own file format. - Anything that makes life easier for users!

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About Thomas Graabæk

Thomas Graabæk has been working 10 years as an architect, with a clear interest in the digital tools used for sketching and detailing, but also with 3D modeling and visualization. Since 2006 he has been working as a BIM Manager, and his main focus has been BIM in general and particularly OpenBIM, trying to bridge collaboration between disciplines and software platforms. Since 2012 he is a partner at BIM Equity.
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