If I receive an existing plan in AutoCAD 2007, can I generate a Revit model from the file in Revit Architecture 2011? Is there anything I have to do with the file, or does it have to be generated in 3D when it was built in AutoCAD?
You can use the DWG to generate a Revit model in that you can use the linework from the file to reference when creating the elements in Revit. You might want to take a look at the following external blog post from BIMUzer, which reviews the process: Starting Your Revit Model from a 2D AutoCAD Drawing. It was written for an earlier release of Revit, so some of the tools are not accessed the same way anymore (for example, in Step 1, "File –> Import/Link – CAD Formats" would be Insert > Import CAD). There is some information in the Help menu too: Using Information from Other Sources.
Hopefully this information helps! If you have any specific questions about the process please do not hesitate to ask!
Katie answered your question - but after reading it I thought you might appreciate a bit of clarification.
You cannot, as far as I know, auto-generate or convert a 3D Autocad model to a BIM 3d model. Autocad objects and blocks are not Revit elements. You have to create original Revit elements if you want it to work as intended. But you can use the original 2d or 3d model as a background to basically build a new model in Revit. Depending on the model and your understanding of Revit, you can go through the recreation process fairly quickly.
After building your new Revit model - jettison the autocad file or it will just make problems for you. Some have suggested in these discussions that AutoCad and Revit are not friendly with each other. Your best practice is to combine the two as little as possible. With the exception of 2d details that you may already have drawn up.
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