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Spline overshoot

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Message 1 of 7
Anonymous
279 Views, 6 Replies

Spline overshoot

I have a problem with fit point spline which overshoots the fixed points. in particular the first and last points.

I noted that another Fusion user had a similar problem i.e. spline could not be fixed to a point. 

 

Is this a bug?

Screencast attached.

 

Best regards

Bjørn

 

 https://autode.sk/2Za9LiQ

6 REPLIES 6
Message 2 of 7
g-andresen
in reply to: Anonymous

Hi Björn,

in my understanding, that's expected behavior.

If you want to have a sinusoidal course to the endpoint, you have to let the spline overshoot on both sides and then trim these ends.
The control points must in principle be set as follows:

sinusoidal splinesinusoidal spline

günther

Message 3 of 7
Anonymous
in reply to: g-andresen

Hi
And thanks for your reply, this is ecactly what I did to over come the
problem, but I just thought that I could be a Fusion problem.

Best Regards
Bjørn
Message 4 of 7
jeff_strater
in reply to: Anonymous

@bjsscp , fit point spline is not really meant to a mathematically precise curve.  It really just tries to find the "nicest" curve that fits through those points.  This is where the "overshoot" comes from.  However, each fit point also has tangent handles, which can be edited to reduce or eliminate that overshoot.  Making the initial and final spline tangent directions horizontal and vertical can help.  Then, dimensioning the lengths of those handles can give you some control over how the spline behaves at those fit points.  I can't guarantee that this is a true mathematical sine curve, but it is closer, I think, to what you want

 

 

 


Jeff Strater
Engineering Director
Message 5 of 7
g-andresen
in reply to: jeff_strater

Hi,

I think @jeff_strater  s approach is much too complicated and delivers a miserable quality.
One must also note that splines are not only determined by the position and length of the tangents, but also by their angles and curvature.
I created the above procedure again with the necessary constraints and parametrically. 

The ends don't have to be trimmed.

sinus.png

So you can better approximate the curve to the sinus.
I think the quality speaks for itself.

günther

günther

 

Message 6 of 7
Anonymous
in reply to: jeff_strater

Hi

 

Thanks for taking the time to answer, I guess what I am looking for is a way to enter a sinus function which is not possible in Fusion, but is available in Inventor.

 

Best regards

Bjørn

Message 7 of 7
Anonymous
in reply to: g-andresen

HI 

 

Thanks, this looks really nice.

I will try this.

Best regards

Bjørn

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