Curve.PointAtParameter for Nurbs bug?

Hi,
does anyone have an explanation why when using Curve.PointAtParameter on a nurbs curve the first point is placed with an offset? This happens both at the start and the end of the curve… and it makes no sense to me.

See attached photo for the result I was expecting, where I used a normal Line element and got a consistent distribution of points.

Hello,
here may be a potential lead to your problem

cordially
christian.stan

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NURBS = Non Uniform Rational B-Spline. The non-Uniform aspect is the important bit.

Unlike uniform geometry (ie: a line) the formula defining any nurbs curve doesn’t have uniformly spaced parameters. I discussed this in some detail in a Dynamo office hour way back in like 2021: 08 - Computational Geometry: Model / Physical types​ with Dynamo - YouTube
(time might be3 a bit off so check around that location).

You can also test this yourself using a NurbsCurve.ByPoints node where you use only 3 points and adjust the X and Y value of the middle point (keeping it between the start and end point).

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Thanks! This workaround works! :partying_face:

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It’s a bit more clear now :smile: thank you for the explanation!

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