# Point by parameter along curve

Is there any way for placing a point on a curve by T parameter? The T parameter considers that the start of the line is T=0, and the end of the line T=1. So if I want a point to be placed in the middle of a line I place it in T=0,5 and I do not mind if the line changes its length. The same for T=0,2, etc…

I suppose that you will find a few answers. Are you working in 0.6 or in 0.7?. If the latest, just type “at parameter” in search in the library and you will find what you want

If you type “at distance”, you will find the equivalent methods for creating points (or planes and coordinate system) related the real distance.

I have seen in another post of you that you are an expert in Generative components. Here someone is trying to follow a classic GC workflow in dynamo:

http://dynamobim.org/forums/topic/how-to-subdivide-a-surface-to-polysurface-in-0-7-0/

Maybe you will find it interesting

Hello Rafael Roa,

As Eduardo mentioned you can use Curve.PointAtParamter and pass parameter as 0.5 to create point at the middle of curve. If you want to create multiple points between 0 to 1 then you can pass parameter as 0…1…#10, this will create 10 points on curve, and points will update as per curve length.

Hope this will help.

Thanks,

Ritesh

Further to Rafael’s question, is there a way to do place point (at parameter) along a spline? I see curve and surface but no spline.

yours, jp.

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The curve methods AtParameter or AtDistance take straight lines, arcs, circles, ellipse, ellipse arcs and splines (nurbscurves in Dynamo). And polycurves too.

Hello John Peterson,

PointAtParameter and PointAtDistance are methods on Curve, so it should work for any curve type.

And as Eduardo P. Roca mentioned, spline is NurbsCurve in Dynamo.

Do let me know if you are not clear.

Happy to help

Thanks,

Ritesh

Eduardo, Ritesh

Thank you for your responses. I have found the node but I now am having some difficulty with using it. If you look at the image below you’ll see an error for the simplest attempt (a mid point along the line). I have the latest build of Dynamo installed and I am trying this on Revit2014. Any suggestions? jp

Hello John Peterson,

You have to pass output of Select Model Element node to CurveElement.Curve node to get abstract curve, then you can create on that Curve using Curve.PointAtParameter.

Thanks,

Ritesh

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Do you guys know what happened to this node??? RIP???

Super Sad. Tested in both version 8 and 7.

Hi Angola,

As stated above, you need to extract the curve geometry from the model curves first with either “Element.Geometry” or “Element.Curves”.