Smart curve rebuild / curve simplification with tolerance in Rhino?

[idigikipfer]

Hi everyone,

I’m working with curves in Rhino 8 and I keep running into the same limitation with the standard Rebuild command.

As far as I understand, Rebuild always redistributes control points evenly along the curve, regardless of the local curvature. This often leads to unnecessary control points in flat areas, while important features (sharp bends, corners, strong curvature changes) are not treated any differently.

What I’m looking for is a more “smart” rebuild / simplification workflow, for example:

• Keeping points at obvious corners or strong curvature changes
  (ideally defined by an angle threshold in degrees)

• Removing or reducing points that do not significantly influence the geometry

• Or fitting a new curve to the original one with a maximum deviation / tolerance value

• In general: adaptive point distribution instead of uniform spacing

I know this is often called curve simplification or tolerance-based curve fitting, and I’m aware that Rhino does not seem to have a direct “smart rebuild” command.

My questions:

• Is there a recommended native Rhino command, script, or RhinoCommon method for this?

• Are there Grasshopper components or workflows?

• Are there plugins that are commonly used for this in Rhino?

• What would be considered best practice in Rhino for this kind of task?

Any pointers, examples, or recommendations would be highly appreciated.

Thanks a lot!

[Helvetosaur]

My suggestion is to try Elmo in the current WIP

[brvdln (Brv)]

As suggested, “Elmo” test in Rhino WIP.

Elmo - Rhinoceros 9 - wip

Rhino WIP Feature: Elmo. A new Rebuild command for Curves

Great work, thank you. I also conducted a simple test, as discussed earlier. I think Elmo can currently reconstruct freeform curves well and can control the smoothness of the curve through options. However, if the curve is composed of straight lines and arcs, the results seem less than ideal. It still cannot fit and maintain the original shape of the straight line area very well. [image] The following image shows a curve I redrawn using the Curve command, which effectively preserves the sha…

[Rhino_Bulgaria (Bobi)]

I wish that Elmo was able to detect true arcs and nearly-arcs (very close to true arcs, albeit still not 100% arcs by definition), in order to produce degree 2 segments with the minimum control point number. In your example, the arc of the input curve object (originating from a circle) consists 3 control points, but then was replaced by a curve with 4 control points.

[idigikipfer]

Thank you, this looks like the best solution I’ve seen in Rhino so far