Rhino WIP Feature: Improved Rebuild command for Curves

Serengeti (Rhino WIP)
1

In Rhino WIP, Rebuild now uses new adaptive rebuild technology to match the shape of the input curve with higher accuracy compared to (the now renamed) RebuildOld, given the same number of control points.

image
image852Ă—474 7.08 KB

What is Rebuild?

The Rebuild command reconstructs selected curves or surfaces to a specified degree and control point number.

Why would you use it?

Curves with many control points generate complex surfaces which are difficult to edit downstream. Rebuilding curves to lower the count while maintaining the curve shape within tolerance is key when modeling. Surfaces created from simple curves will be easy to use for form finding or manipulating with other commands.

Some examples where Rebuild is useful:

  • To rebuild section curves made from scans (mesh objects)
  • To rebuild curves to the same amount of control points (useful for Loft and Sweep commands)
  • To rebuild curves that are a result from intersections of surfaces

User Interface

We’ve redesigned the dialog box to include the options for the new Rebuild command.

image (13)
image (13)564Ă—698 35.5 KB

Kink Splitting options are available only after you start rebuilding one or more polycurves.

Examples

Rebuilding a curve with many control points to a single span degree 2 curve:

image
image852Ă—474 7.08 KB

rebuild-ex1.3dm (57.2 KB)

Rebuilding a degree 2 polycurve containing 3 arcs to a degree 5 curve with 7 control points:

image
image1065Ă—970 11.9 KB

rebuild-ex2.3dm (59.6 KB)

Try it out…

Download the Rhino WIP

18 Likes
Rhino WIP Features
2

Does that mean that the new Elmo technology will not be used for rebuilding surfaces in Rhino 9, and implementing it is postponed for Rhino 10 instead?
I read in another topic that it “may” be developed for Rhino 9, too, but the new topic’s name makes me wonder about that.

3

This is awesome! Have 1% wondered about this everytime I’ve typed “Elmo” for the past decades. What are the Grasshopper equivalent commands?

5

I did some tests with some of my files using the new Rebuild and RebuildOld commands; the new command is approved. :raising_hands:

1 Like
6

I imported a logo (.svg or .ai) in Rhino and used it a project then exported to blender also 3ds max but couldn’t extrude it.

Then I extruded the logo in Rhino and exported to blender and 3dsmax.

The logo has soooo many points like you show “original” curve. With Elmo, that kind of problem will not be existed, I hope.

Thank you so much…..

One question,

I use simplifycurve command if I get a drawing from someone or making 2d from a mesh.

Does Elmo rebuild multiple curves at once and rebuilding curves make Rhino running faster and smaller files?

7

This new rebuild technology can potentially rebuild with fewer control points at the same deviation, but pls try it on your files and share the results. Again, Rebuild currently doesn’t have all the features of the commandline version of Elmo.

1 Like
8

no, but there are no guarantees yet that this new tech can be applied. In Dale’s words:

For v9, we are investigating if the new algorithm can be used to improve surface rebuilding. If it works better, we’ll add it to v9.

1 Like
9

Lets hope that it can be implemented, because rebuilding a dense surface into a single-span degree 5 with 6 control points is a chaotic nightmare now. :slight_smile:

At least new “Rebuild” command is a good start for simplifying dense curves. It seems like the perfect way to clean up some fonts, too.

2 Likes
10

In current WIP, you will now see this dialog for Rebuild:

image
image724Ă—1096 72.4 KB

Kink splitting options are only available once you start rebuilding one or more polycurves.

Access to old Rebuild is still available as RebuildOld

5 Likes
11

Great new feature. Is this Rebuild Command also available in RhinoCommon? If not, is it planned for Rhino 9?

12

This looks lika a major improvement. Thanks! E.g. offset curves often have LOTS of control points and it is always a lot of work to simplify them while keep them parralel. Even if my workaround works well I love saving time! Looking forward to the GH component.

13

Hi, Cool, but does this mean the new rebuild curve is still a three-point simple curve? or a Bezier curve, so when outputting as a dxf for profiling on cnc machines, it will have lots of points again?
on some cnc machines, they can’t handle Bezier curves and need simple 3-point curves but not loads of them….

14

no, not yet, I will update this thread when that becomes available

1 Like
15

@adrian to convert curves to lines and arcs, Rebuild is not the right tool. You should use Convert for that.

1 Like