Hi everyone,

I am getting stuck for finding a solution to determine the radius of culvature on a curve located in 3D coordinate system, which helps me to check the radius of any point in a 3D curve.

I know in Rhino 3D or in AutoCAD I can check it freely. But in Revit, there is no such function like that.

If you have this curve in AutoCAD file link it to Revit and use bimorph package to get the geometry of it.

@ingenieroahmad Hi, I have BimorphNodes package, but I don’t see any nodes for the purpose checking the radius of curvature.

when you get the geometry you can deconstruct the polycurve to curves and get the required redius.

It’s a good idea but not enough for me haha.

Look at the photo below. I used the node Curve.ApproximateWithArcAndLineSegments and received almost lines instead of arc. With lines, I can’t define the radius. Sometimes, I have a nurbscurve extremely smooth which deconstructing it only give me lines.

The diagram you posted indicates the solution.

Take a sampling of three points on any section of the curve. Draw an arch through the 3 points, and pull that radius.

Some loose design script on my phone which can serve as your guide (likely a typo in there - you can map to nodes or try editing as needed):

```
crv = nurbsCurve;
n = distanceOfRadiusSample;
o = offsetDistance;
pnts = Curve.PointAtSegmentLength(crv,[n-o,n,n+o]);
targetArc = Arc.ByBestFitThroughPoints(pnts);
sampledRadius = targetArc.Radius;
```

I feel myself so silly by keep paying attention in the math function than having a look at the geometry.

Thank you for the hint.