Getting models from Revit into Unity?

Hi everybody,

I have a question but first let me tell you about my situation:

We're using Revit (I'm testing with Revit 2009 MEP) at my company and I'm investigating the possibilities of using Unity to create interactive walkthroughs (gamestyle). The trouble is, Revit really only exports fbx, ascii, dwf, dwg and dxf. Since Unity should be able to import fbx and dxf files, I tried that.

Here's my question: I do see the import settings dialogue but can't seem to do anything to make the model visible. Am I doing something wrong or is it Revit?

I'm using the trial version of unity Pro. Apart from AutoCAD and Revit, we don't have any other 3D CAD package.

Hope you can help.

Sicerely,

Remco Boersma

This might be a long shot, but as far as I can tell without having a real try but by judging what I can find on the net, Revit seems to create (and therefore export to FBX) spline (or NURBS) data instead of polygons, just as most CAD tools do for mesh quality reasons.

Unity is not able to convert those NURBS data to polygons, which it needs, and that might be why you are left with no imported object. (Just confirmed that by trying to import some NURBS data from Maya to Unity via FBX 2011.)

The solution, given that I'm correct with my conclusion about Revit using NURBS, is quite simple: Tesselate your objects.

Tessellation means breaking down your NURBS objects in Revit to polygonal meshes. Unfortunately I can't point you to how you can do that, but I bet that you can find the solution in the Revit documentation, now that you know what to look for. You might probably fiddle around with the tessellation resolution a bit to find a good compromise between a high poly count and visual quality, but judging from my experiences with Catia and PowerEngineer you will end up with pretty nice meshes.

I hope that helps. :)

When looking at the imported Model (in the Assets window), do you see it in the Preview window (at the bottom)? If so, then it could be a problem with scale - the default Import Settings are set to 0.01. Try setting them to 0.1 or 1, then drag-drop the Model onto a scene and see if it shows up.

It could also be a missing Texture - you need to move it to the Assets folder, then apply it by hand, to your Material. It doesn't get done automatically.

For a temporary fix, you could try exporting it from fbx to another format such as obj. Or perhaps you could try importing the fbx file and then re-exporting it as another fbx file.

Here are a few free options:

since a few days I import large REVIT files to unity and other than material attachment problems it works great! I can run around my project in unity like in a game( wow)…I used Unreal render engine before and failed .

The previous described problem with scaling the model however is correct. once you find your model( fbx file) in the project browser you drag it into your scene…click on its name in the Hierarchy list to check if is there.

-change its scale parameters and ( Inspector)
-did you ever try to import a 3dmax model as a test object? If you succeed here you at least now , that you are on the right path.
good luck!

btw our engineers here use Naviswork for clash detection…works perfect, but unity is way more fun I have to admit!

are any of you still using Revit to port models into Unity? I am have issues with scales. Everything I bring in appears very small, and would like to know the perfect scaling factor to increase the models in Unity. Is Unity metric?

BIM-VR plugin can handle this, QQ gourp: 295342506

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There’s also an online tool available that will do what you want. It takes any autodesk fbx, (including Revit) and converts the materials for use in Unity and Unreal Engine. I’ve used it a lot myself and it’s worked really well for me:
http://materialconverter.com