Tuesday, November 20, 2012

Revit 2013/AutoCAD MEP 2013 IFC Improvements

This post is part of an AU class this year, MP1465, Supercharge Your AutoCAD® MEP 2013. It came up as we started working with outside vendors that are solid AutoCAD MEP users, but not Revit users - and that's what we're using.

First up, know the rules:
- Architecture and Structure items convert pretty nicely, with ACAD Arch walls converting to Revit walls. You may need to swap some styles, check justifications, etc. but getting the overall model works pretty well.
- MEP objects come into Revit from ACAD MEP as in-place families, but if you setup your import options, and have your classification definitions assigned to MEP objects in ACAD MEP, then they come in as "pipes, pipe fittings, duct, etc.". Be aware - they don't have the same behavior as a duct, pipe, etc. that was created with native Revit tools. But you can add connectors as needed to make these types of connections.

Here's the excerpt from the class (or as I like to call it, the "tease")...

IFC stands for Industry Foundation Class, and it’s a file format that is universally shared between CAD platforms. The intent is that an object in a program like AutoCAD MEP can be converted into the same type of object in Revit, or other BIM applications.

In order for an object to be exported to IFC, it has to have an object classification assigned. To look at the default styles go to ProgramData\Autodesk\MEP 2013\enu\Styles directory and open the IfcShareBldgElements (MEP).dwg file.
In the style manager, look at the classification definitions under Multi-purpose objects. IFC properties can be assigned to these objects:


Once the items are selected, the classifications tab lists the information associated with an MEP object that will be exported:
To use these in a file, and assign them to MEP objects, you have to copy them into your current drawing. Use copy and paste in the style manager to add both classification definitions to the current drawing.
Select OK to exit the style manager. Now that they’re in the drawing, you can edit the properties of objects to assign the classification. I’ll grab the ductwork, and then go to the properties palette:
For most other parts, IFC Type Classifications are mapped to MvPart Objects (such as equipment, panels, and devices) automatically. This classification is added in the Autodesk Catalog Editor by default. You can modify this classification or add more classifications to the content library in the Autodesk Catalog Editor.

Once you’ve added the correct classifications to MEP objects, review the IFC export settings. From the application menu, select the Export tool, and then select IFC. The options are located on the export dialog, and the object tab lists all objects that loaded into a drawing – you can choose to add or remove objects as needed.
After you review the options, you can run the export. The IFC file is created in the project folder. To test this, I’m going to open the file in Revit. Before doing this, open the IFC Import options on the Application menu, under Open:
Before importing an IFC file, you need to go through and map IFC class names to Categories and sub-categories. This tells the MEP object what is used to control its display in Revit.
Once the IFC file is imported, it will appear something like this:
The imported objects take on most of the characteristics of the equivalent objects in Revit. You may need to check IFC mappings in both the AutoCAD MEP file and the Revit file during this process, but this represents a major leap in compatibility between the applications.
Be aware that imported objects may not completely take on the behavior of a normal duct. For example, the duct is treat like a duct with properties assigned, but it does not include the connection, system or sizing behavior. You have to add a connector to attach duct to it.
I don’t care what anybody says…this is really cool…
Happy BIM'ing - see you in Vegas!

1 comment:

alekz said...


Thanks for your post, it's very helpful.

I have an issue related to this workflow. Hopefully I can pose the question in a manner that's easy to understand....When assigned property set definitions to an MVpart in AutocadMEP, a list of Psets come up based on type classification. How do I know which of these property set definitions pertain specically to the part? An example would be a diffuse. When I try to assign the tables, indeed the list comes up, with diffuser being one of the tables, but I also get others that dont seem closely relational.

How do you go about choosing the right tables for the right part?

Thank you in advance!