How to recreate the same curve using minimum points

Hi ,
I am trying to recreate the exact same curve using minimum or least number of points. I have given a shot but I see I am loosing the geometry as shown in fugure. I am trying to get rid of undesired points using concept of curvature.

How can I recreate the entire curve with min points without loosing the geometry ?
query1.3dm (36.6 KB) (13.8 KB)

with the rebuild node it should work fine. make sure your degrees are 3 or more to get something that’s not a polyline.

Thanks @benedict for your repsonse. I want to obtain all those points (Minimum number of points ) used to recreate the curve. Can you please help as in Gh file ?


the geometry i8n your file is not internalized. Also I am not sure to understand what you want to get in the end. the same curve but with less points or the same curve with given points?

I need the same curve but with less points (Minimum number of points) and thier co-ordinates.

like this? (3.2 KB) (13.8 KB)
optimize.3dm (48.1 KB)

Referring to gh file I have attached I am deleting off the points in red i.e whenever a segment of curve approches a straight line I am deleting off those points. But on doing so I am loosing a bit of originality of the curve.

Is there any way I can fix this ?


Just looking at this, your initial curve has 36 control points which, given the amount of twists and turns is rather a good number. Some control points may seem superflous, but they are necessary to constraint the curve in neighbouring sections.

The rebuild operation leads to a 62 points polyline, so better keep the original ?

Do you want to approximate your curve by a polyline ? A PolyArc ? Or keep a NURBS curve ?

In the first case I’ve made a C# script that removes the “best” vertex each time until a target count is reached.

In the last case I’ve made another C# script that searches for vertices that can be removed - in this case, 4 - without affecting the shape too much.

Hope this helps… (20.3 KB)


Since your goal seems to be to fit a polyline into a three degree curve, you should know that there is no optimal solution. You can always just do an approximation of sorts and lose some definition/curvature here and there. Less fidelity translates to fewer sample points.

Like @magicteddy, I have a couple of curve resampling scripts, but it would be good to first know what you’re end goal is?

2023-03-19 09-26-57.2023-03-19 09_28_17

Similar to @magicteddy’s script, I get an acceptable result in terms of fidelity at around 70 to 80 points, depending on which method I use.

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whenever a segment of curve approches a straight line I am deleting off those points

Hey @magicteddy first scipt is exactly what I wanted. As your name says its truly magic ! I really appreciate your help. However I was trying to convert the C script into grasshopper as I am unfamiliar with coding. Althogh I have understood the logic.

I was womdering If you can help me to do it in grasshopper. I have given it a shot though.
It would be really helpful if you can help me. (16.7 KB)

My script implements a while loop in which the same list of points gets updated at each iteration. This is impossible to reproduce using standard GH components - which is why I chose to use C#.

If you absolutely need to use components, you’ll need Anemone or Hoopsnake plugins to simulate loops.

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