4 Ways to Coordinate Data between Revit and Civil 3D

In a perfect world (and, hopefully, in reality) no one would choose to work in a silo on a complex building project. Whether you're primarily an Autodesk Revit user or a Civil 3D user, you've likely encountered a situation that requires you to work directly with someone using the other software program. There is Revit and civil 3d interoperability available to us.

Though data is handled differently in Revit and Civil 3D, there are multiple ways that you can coordinate to make collaboration a pain-free process. Read on to learn how you can share your project data in a meaningful way.

#1: Create Shared Coordinates

You have the ability to create a shared coordinate base point between Civil 3D and Revit. In versions prior to 2018, this was available as a subscription add-on. Beginning in version 2018, this functionality is built directly into the software. As all Civil 3D users know, when you're working on a Civil 3D project, you work inside a coordinate system. In Revit, every project has internal coordinates for the elements in the model, but those coordinates are applicable to that project only. Creating a shared base point in Revit ensures that when you bring information from Civil 3D into Revit or vice versa, it ends up in the correct location.

#2: Import Civil 3D Surfaces into Revit

There are multiple ways that you can bring your Civil 3D surface data into Revit. You can export the surface data into an XML file and import that into Revit or you can link the AutoCAD data from Civil 3D as background information in Revit. To export the data and import it into Revit, select Export to LandXML from the Output tab and choose exactly what data you want to export, and, then, import into your Revit project from the Site Designer tab. When importing the LandXML, you can use the shared coordinate point that you created to position the imported surface data correctly.

#3: Import Civil 3D Corridors into Revit

Civil 3D corridors can be brought into Revit as AutoCAD solids. If you have roadway corridors, for example, you can select the corridor model and Extract Corridor Solids to create solids of all the roadway elements, including curbs, gutters, paving, and sidewalks. In Revit, you can either Link or Import the CAD file to insert the newly created corridor solids.

#4: Import a Revit Model into Civil 3D

From your Revit project, you can export a Building Site as an ADSK exchange file. This export function allows you to select exactly which attributes to export, such as building footprint, building model, property lines, and the site model. In Civil 3D, you can insert the Building Site from the Import drop-down menu. When you import the information into Civil 3D, you also have the option to display or hide each attribute that you exported from Revit. This imports the Building Site as a solid object in Civil 3D. If you are hoping to interact with the terrain model or individual components, you need to explode the object and create a surface from the TIN lines. You can also export the Revit project as AutoCAD linework. However, in this scenario, there is no reference back to the Revit model, and the surface will, therefore, not update in the Civil 3D drawing if changes are made.

Webinar Q&A

When the Civil 3D XML is imported into Revit, is this a surface or a volume that can be cut into sections?
It's actually just its own type of object. Again, to create that as an actual surface item, you're going to actually have to explode that and turn those TIN lines into a surface. Now, they are 3D objects and you can view them as a section, but they are not considered to be a section or an actual surface item.

Now, remember, inside of Civil 3D, whenever I select an object, I always get my ribbon changes based on how I want to work with something. You'll notice that when I select this site object, nothing changes on my ribbon. So it doesn't really recognize it as anything. So, for instance, if I was going to try to draw a section and here and I select this again, it doesn't think that it's a surface or solid object or anything like that. I would actually have to project this object into a profile view, a section view, or something along those lines. It's really just a 3D reference object from Revit.

If I delete the XML file, will I lose the surface in Revit?
No, you will not lose the surface because it was already imported.

Can I assign material to this object in Revit?
So, if I do bring in an XML file, yes. Inside my surface area, when I bring in an XML file, and I'm inside of the site designer, it recognizes it as an actual object inside of Revit. So that's something you can assign a material to.

The shared point looks like it coordinates the Revit model and Civil 3D horizontally. How do you handle the vertical coordination (i.e. placing the building at the correct FFE)?
So, when I set the survey base point, I just put in northing and easting. But, what you can do, is when you match that up to your finished floor elevation, for instance, go to the 3D view and look at the survey point. If you select it, you'll see that elevation is right there as well. So it's not just X, Y or northing and easting, but I can set the elevation information of that base point as well.

Do the Civil 3D and Revit shared coordinates match when you import the file from Civil 3D into Revit?
Yes, they do. That's the whole point of the shared coordinate there. Now, of course, Revit doesn't actually work with coordinate systems the same way. But you're kind of, in a way, tricking the Revit environment into a world coordinate system, or a state plane coordinate system there. So yes, those coordinates do match. You're just telling the coordinate inside of Revit, "hey, this is the coordinate out in the real world."

In Revit, are Civil 3D imported objects and surfaces editable or will these need to be reconstructed in Revit?
If you import the XML file and it creates a Revit surface, yes, you'll notice that it will work within the Site Designer, so you can actually edit the terrain and work with it. When you select that object, it is going to be a Revit-based surface at that reference point.

If you created a toposurface in Revit, would you be able to create a volume in Civil 3D?
It depends on how you get that information over to Civil 3D. If you create it as a building site, no, you're not going to be able to. But, what you could do is export the toposurface from Revit not as a building site, but a CAD drawing, which would export the triangulation lines as 3D lines. Then, when you bring that into Civil 3D, you could create a surface out of that and create your volumes from there.

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