Some architects like to begin their design in CAD software tools. CAD drawings are then imported/linked in Revit to be used as references/underlay. REVIT model geometry is then built by tracing over elements in CAD file. Another popular reason to import CAD files into Revit is to use them for detailing purposes. If you already have some details drafted in CAD, you may import them in Drafting view and use them in Revit.
You can either import a CAD file or you can link it. If you expect the CAD file to change, it is best to link it. If the CAD file is revised, then you can simply reload the linked files in Revit and see those changes. However, if you do not expect the CAD file to change, it is best to Import it. Importing a CAD file will increase the size of the Revit project file, but in turn will use less memory.
Link a CAD file containing the Ground floor layout of the sample project into Revit and place it on the “00 Ground Level” Floor Plan as shown below.
Files required for this tutorial:
If you do not have the following files, please download them from here.
“Ground Floor Layout_For Import.dwg”
Make sure that you have the CAD file “Ground Floor Layout_For Import.dwg” and have prepared it as per the tips in step 2.
Prepare CAD file before importing:
Open your CAD program and make sure you have done the following:
Have only those geometries/layers in the CAD file which are necessary for you to use in Revit (this will reduce the file size and the memory required in Revit). You may also choose to Freeze the layers which are not required.
Many CAD users like to put layouts, elevations, sections, etc all in one CAD file. Do not crowd multiple drawings in one CAD file while importing in Revit. For example, if you are importing a layout drawing of a particular floor, try to have only that layout in the CAD file. If necessary, copy the geometry you would like to import and paste it into a new CAD file, to avoid any unnecessary references.
Purge your file before importing.
Check if drawing units and file units are consistent.
If you need Xrefs, then bind them in your drawing. If you do not need them, unload/remove them.
Copy the original file before modifying for import. Just in case, if you need to get back to the original version.
To Link a CAD file in Revit:
Open the tutorial file ‘TutorialImportCAD_Input_LearningRevitOnline.rvt’ in Revit. This project file already contains model geometry for basement floor, grids, levels and section views.
Navigate to the floor plan of “00 Ground Level”.
Go to Insert tab -> Link -> Link CAD (If you would like to import a CAD file not link it, you may chose to go to Insert tab->Import-> Import CAD)
A Link CAD Formats dialog box will appear. Use following Settings:
Check the “Current View Only” checkbox if you want this CAD file to be visible only in the view it is being imported (Ground Level Floor Plan). If you do not check this box, the CAD file will appear in all views, including 3D views.
Colors: Preserve (if you want to preserve the colors of the layers in CAD file).
Layers: All (If you choose to import only visible layers in CAD or choose Specify option if you would like to import only selected layers. The selection option will appear during the import process).
Import Units: “Ground Floor Layout_For Import.dwg” used for this tutorial has been created in Imperial Units (Inches) while the model in Revit is being created in Metric Units. To import this file correctly, choose “Inch” in the Import units.
Positioning: Auto-Center to Center (this will place the center of the CAD file to the center of the Revit view). Choose other options if you would like to place the CAD file Origin-Origin / By Shared Coordinates.
Place at: 00 Ground Level is seelcted by default as we are trying to import the CAD file in the active view.
After selecting all the Settings as above, click Open. This will import the CAD file in the view.
However, note that CAD file imported is not at the correct position.
To move the CAD file to the right position, use Move tool.
Select the object (in this case, the imported CAD file).
Go to Modify panel -> Modify -> select Move tool.
Alternatively, use “MV” as a keyboard shortcut.
Click to enter move start point. In this case, it would be the top left corner intersection of the center line in the CAD file. This will be the base point for moving the CAD file.
Click to enter move end point. In this case it would be the intersection of Grid 1-A.
Click Esc to end the Move tool.
Once the position of the CAD file is correct, it is best to PIN it. It will prevent you to move/ delete the file by mistake.
To Pin the CAD file:
Select the CAD file.
Go to Modify panel -> Modify -> select Pin tool.
Alternatively, use “PN” as a keyboard shortcut.
The CAD file is now pinned.
Click Esc to end the Pin tool.
NOTE: If you would like to Unpin the CAD file,
Select the CAD file.
Go to Modify panel -> Modify -> select UnPin tool.
Alternatively, use “UP” as a keyboard shortcut.
The CAD file will be unpinned.
To give the visibility of an Underlay for the CAD file (in order to avoid confusion between Revit model geometry and visible geometry of CAD file), the imported geometry can be set to halftone or some of the layers can be turned on/off.
To control the visibility of the CAD file:
Go to View tab -> Graphics panel -> Visibility Graphics -> Visibility Graphics Override dialog box will appear.
Alternatively, use “VG” as a keyboard shortcut.
Go to Imported Categories tab.
Check the checkbox for halftone.
TIP: To turn on/off particular layers, use checkbox besides the layer names.
Note that the CAD file in the drawing area is now grey/halftone.
As we have linked the CAD file, it will be possible to see the changes if the CAD file is updated by reloading it.
To Manage the linked CAD file:
Go to Insert tab -> Link panel -> Manage Links -> Manage Links dialog box will appear.
Go to CAD formats tab.
The linked CAD file will be listed here. Select the row of the linked CAD file.
Click Reload to reload the file from the same path.
Use Reload From… option if the path of the file is changed.
If you would like to unload the file from your project, choose Unload. You can at a later stage, use Reload to reload it in your project.
If you would like to completely remove the file from your project, choose Remove. You cannot Reload the linked CAD file, if you have removed it. You will need to link the file again.
After completing all the steps above, Save your project file.