Need Help Understanding Curve Parametrization

Hi, this is a simple script where I want to extract a curve of a particular length from an existing curve.

Let us say we need a curve of 1500mm, equidistant from some point on the curve. I take some random point on the curve and get the parameter of the curve at that point lets say parameter A.

I remap 1500 with the curve length and get a parameter value which I divide by 2 and then add and subtract with Parameter A. After using these two new parameter values to shatter the curve however, I dont get the curve with the length of 1500.

Can someone help me with this :confused:

curve parametrization.gh (15.5 KB)

if you are dealing with Lines then parameter and Length walk at the same speed, but if you are dealing with Curves in general then parameter and length will probably walk at different speeds…
despite that, instead of using parameter, I would suggest to always use Evaluate Length to get portion of Curves with a given Length, because it’s going to work fine whatever type of Curve you’ll get

curve parametrization_Re.gh (14.0 KB)

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This method, moves shatter at the start, and evaluates length from both ends of the split curve. Gives you parameters on the original curve using CCP and simplifies output using sub curve

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Does this work for you?


curve parametrization_2024Oct17a.gh (12.9 KB)

P.S. This version replaces your fixed point with Point On Curve (blue group), which works fine except for Linear Dimension between the pipe endpoints which cuts the corner instead of following the pipe!

curve parametrization_2024Oct17b
curve parametrization_2024Oct17b.gh (12.1 KB)
curve parametrization_2024Oct17b2

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Thank you everyone, I learned that I need to use Evaluate Length and when doing such kinds of operations. Appreciate the quick responses from all :smiling_face_with_three_hearts: