DirectShape Brep always converts to mesh

I would like to add Rhino Brep as a DirectShape into Revit but every time it is converted into mesh.

Not always, just when Revit rejects the brep geometry. There are many reasons for this. Common issues are:

  1. Edges less then a mm
  2. Too many control points
  3. Multi knot surfaces, that may be forced sweeps.

Do you have an example? We can analyze the shape, we are trying to classify what works and what doesn’t.

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I put it in the wrong words - of course, not always :).
I recreated the shape and had good results but nonetheless, maybe it is good to investigate.

The starting internalized Brep, which gives bad results is indeed a bit skewed, but also walls around that structure are like that so… However, every Brep face is planar.
I’m curious to know how to deal with Rhino geometry to be sure that I will get good results every time.

The second, good geometry is just extrusion from profile.

GH File: directshape (39.7 KB)

Thank you for this sample it is helpful.

I took the original Brep:

  1. Explode it
  2. Rebuild Edges command
  3. Join back together

The original shape now translates properly? Do you also get the same result?

When we see this the problem is that the original tolerance that the model was joined under was too big and the original join changed the edges too much. It is good to know this is one more thing that Revit is not happy with in BREPS. But, trying figure out how the model got in this state is important.

Where did this model come from? Did it get scaled larger at some point? Come from another file format?

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I made it in Rhino. It was based on some input curves I received, and I made this brep in some sketchy manner.

Rebuild Edges indeed helped me, thank you for this tip.

We will investigate it further. But something changed the edge tolerance of the brep join. Just one more thing we need to be aware of I guess.

Hi, what is the advisable tolerance for the Rebuild Edges? 0.01?

Try 10x document tolerance

Revit tolerances are

  • 0.1 mm
  • 0.0001 of a meter
  • 0.006 of an inch
  • 0.0005 of a foot
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Just to clarify, if my file is in meters and at 0.01. I gotta do 0.01x10 = 0.1
That is my rebuild tolerance?

Correct, if the goal is to remove as many out of tolerance errors as possible on Rhino to Revit geometry translations you’ll need that leeway when doing the rejoin after rebuild.

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