Join Paul F. Aubin for an in-depth discussion in this video Linking AutoCAD DWG files, part of Revit 2018: Essential Training for Architecture (Imperial).
- [Voiceover] When working in Revit projects, it's pretty common to need to access data that's created in some other CAD program. The most popular CAD program is AutoCAD and its DWG format. So if you want to access a DWG or other CAD file in Revit, one of the easiest things to do is to link it. So here on the Insert tab, I have this Link CAD button. And when I click that, it's going to allow me to access CAD files in a variety of formats. DWG, of course, is the default. But you can use DXF or DGN for MicroStation or even SketchUp files.
So I'm going to leave that set to DWG, and I'm going to select this AutoCAD floorplan right here. So let's say that I had a designer that worked up a floorplan in AutoCAD and they sent it over to me. And now I want to use that as the basis to create some Revit geometry. Before I click open, I'm going to want to check a few of the settings here. So let's start with the colors and the layers. The colors, if we leave it set to Preserve, is going to use those bright primary colors that you see in the Preview over on the right. And they may not be easy to read on a white background.
So if you want to leave it in color, it's usually a better choice to pick Invert. Now Black and White is also an option, and that's a good choice if you're going to print out the CAD file along with the Revit project. Now for layers, I'm going to leave it set to All, but there are a few other options. You could choose only the visible layers or specify the layers you wanted. But I think All in this case makes the most sense. Import Units, usually Auto-Detect does the job. But if you need to, you can choose one of the specific unit choices there instead to force it to come into the correct scale if it's not working with Auto-Detect.
Correcting lines that are slightly off axis is not a bad idea for floorplans. Perhaps the only time you might want to uncheck that is when you have a really, really large file like a very large site plan file. And then in some cases, unchecking that can be desirable if there's some accuracy issues when it comes in. For the positioning, there are several choices. The default is Origin to Origin. I'm going to accept that for this example. If we don't like where it comes in, we can always move it before we continue. But Origin to Origin, a lot of folks would prefer that as a first choice.
Now over here, Current view only is a setting that controls how Revit will interpret this imported CAD file. Now let's be clear. The CAD file is just 2D line work. There's nothing 3D about it, and there's nothing in that file that Revit will understand as native objects. However, if you leave Current view only unchecked, even though it's 2D geometry, it'll still treat it like it's part of your model and it will show in all views: 2D views, 3D views. If you check this box, then the CAD file will be treated as view specific information, current view only.
And in this case, meaning it will only appear in my level one floorplan. So I'm going to check Current view only. I'm inverting the colors. I'm bringing in all the layers, auto-detecting the units, and I'm going to bring it in at Origin to Origin and click Open. Now the origin for the Revit file is right about in the middle. And so, you can see that the lower lefthand corner of this file kind of came in right about that location. So that's the Origin to Origin. Now, if you move your mouse near the file and you're not able to select it. Right? Notice that I can highlight it? And when I click to select it, the whole thing selects as a single element.
If you're not able to do this, there's one of two possible reasons why that is. We have several selection toggles available to us in Revit. And two of them might be affecting this file. The first one is the selectability of links. And the second one is the selectability of pinned elements. Now you can access these selection toggles in two places in the interface. The first is down in the lower righthand corner on the status bar. And Select Links is right here. And Select Pinned Elements is right here. However, if you prefer, you can also find those toggles here in a menu just below the Modify tool.
So you need to make sure that both Select Links and Select Pinned Elements are both checked and turned on. If either one of these is turned off, you won't be able to select this file. So just make sure that both of those are active before we continue here. So just make sure that both of those are toggled on if you want to be able to select the file. Now let me just briefly comment on what pinned is. Pinned prevents the object from moving. So if you were to unpin it, you could move it. And I'll undo that. And with it pinned, it won't be able to move.
So if you don't like where the origin put the file, unpin it and move it to the location where you want it to go. Okay, I'm going to zoom in on this file. And what I want to do is use this as the basis to create some Revit geometry. Now whether or not it's pinned or whether or not you can select it, you'll still be able to snap to it. So if I go to Architecture and I go to the Wall command, choose the wall type I want. I'm going to pick a generic 12-inch wall. Notice that it will see object snaps in this file: endpoints, intersections.
It will see those points, even the edges of walls and so forth. If you look really carefully, notice that it also does something kind of interesting here. It's sensing the two parallel lines. Now those are just lines. They're not a wall. But it's sensing where they are and it will snap right down the middle and I'm able to trace over the CAD file and get those walls to be right in the correct location. Now I'm going to press Esc once, change the type to something thinner for the interior like generic 5-inch.
Let me zoom in a little closer. And I'm going to do a few more of these. Now don't try to get too precise just yet because I'm going to clean this up with a trim and extend command. But by just kind of sensing where those center lines are, you can see that you can very quickly start to trace over the line work in this CAD file. And this is the reason that I wanted the CAD file to come in, in color. Because notice that as the color slowly disappears, I can tell where I've drawn Revit geometry and where I still have work to do.
So I'm going to take this wall and just stretch it up a little bit, make it a little longer. And now, let's go to the Modify tab, and I want to clean up some of this geometry. I'm going to use this tool for that, Trim and Extend Multiple Elements. Now the way this works is, you set a boundary edge and then you can select one or more elements to either trim to or extend to that boundary edge. So for the first example, I'm going to use this exterior wall that I just drew and I want to extend this wall and this wall.
So notice how the command stays active as you click multiple objects. If you want to reset the boundary to something else, just click in empty whitespace. And now I'm going to choose this wall as a boundary instead. Revit does not care if you pick the edge of the wall or the center line of the wall. The wall itself is seen as the boundary. You can also do a crossing window like this and select multiple elements at the same time. So instead of clicking them one at a time, you can do that.
Now it's still active, and I could pick additional objects. So until you click in empty whitespace to reset that boundary, it's going to stay an active boundary. This is both a trim and extend command. So if I pick this edge as the boundary and cross through these objects right here, they will extend to that line. But then, if I pick the lower portion here, that's the part I want to keep, notice that it also serves as a trim boundary. So the same command could either be a trim or an extend.
Once I've drawn some walls, now I can go to my Door command. I'll choose an appropriate sized door. And notice that I can place these doors directly into the plan here, and they will cut holes in my Revit walls to match the underlying floorplan. And as I said before, as the color slowly disappears, you kind of know when you're finished. Now, let me go to a 3D view.
I'm going to use the default 3D view icon right here. And I'm going to spin around so you can see what we've created. I'm holding down my Shift and dragging the wheel. And notice that the CAD file doesn't show here. So recall that when we linked it in, I checked the box Current view only. And that means that the only place that the CAD file shows is over here in the level one floorplan. So you use the level one floorplan to trace the geometry. Then when you're done, you've got a full Revit model at your disposal. Now, let's say that the owner of this CAD file made some changes and saved the file.
At this point, if I want to capture those changes so that I can keep going and see if it affects the work I'm doing here, I would want to go back to the Insert tab, click on Manage Links, and then click the CAD Formats tab. Now here on the CAD Format tab, I can select the file. And if they've saved over the original version, I simply need to click Reload. However, in this case, they sent us a version with a new name. So what I want to do is select the file and choose Reload From.
I'll select the one called AutoCAD Floorplan_Updated. I'll click Open and then click OK. And now you're going to see that this adjustment has been made to the exterior wall. And the other thing that's really important to understand there is the Revit geometry is not connected to the CAD geometry. So you would still need to select the elements that need to change. And in this case, I'll use the Move command. I don't want to disjoin the geometry so I'll uncheck that. And I will snap two points. So using the object snaps, I can still snap to the underlying file, but you would need to make any changes necessary to your Revit geometry.
So linking in a CAD file is a really handy way to access data that's been created in other software and use that as a reference or a basis for creating your Revit geometry.
First, get comfortable with the Revit environment, and learn to set up a project and add the grids, levels, and dimensions that will anchor your design. Then author Paul F. Aubin helps you dive into modeling: adding walls, doors, and windows; using joins and constraints; creating and mirroring groups; linking to external assets and DWG files; and modeling floors, roofs, and ceilings.
Paul also shows advanced techniques for modeling stairs and complex walls, adding rooms, and creating schedules. Finally, discover how to annotate your drawings so all the components are clearly understood, and learn how to output sheets to DWF, PDF, or AutoCAD.
- Understanding BIM and the Revit element hierarchy
- Navigating views
- Creating a new project from a template
- Adding walls, doors, and windows
- Adding plumbing fixtures and other components
- Linking AutoCAD DWG files
- Rotating and aligning Revit links
- Working with footprint and extrusion roofs
- Adding openings
- Adding railings and extensions to stairs
- Creating stacked and curtain walls
- Hiding and isolating objects
- Adding rooms
- Creating schedule views and tags
- Adding text and dimensions
- Creating new families
- Using reference planes, parameters, and constraints
- Plotting and creating a PDF