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What is the definition of a Bridging Curve or 3D Fit Spline shape?

SledDriverSledDriver Member Posts: 116 ✭✭✭
edited June 2017 in Community Support
I have just done a test to try and align a Bridging curve over a semi circle, and at no time is the bridging curve semicircular. It is always different. It seems these differences will detract from the ability to make consistent curves, edges and surfaces etc with predictable outcome.

The bridging curve with a Magnitude of 2 and a bias of 0.5 seems to coincide with a semicircle at the end points and at the mid point, but nowhere else. This tends to suggest that at any given magnitude, the resultant bridging curve is perhaps a bit 'distorted' and not a true optimum flowing curve.

Same question for 3D Fit Splines which provide a slightly different 'distortion'.

An example of each can be seen in this document.


Best Answer


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    mahirmahir Member, Developers Posts: 1,296 ✭✭✭✭✭
    Bridging curve is not meant to mimic a circle. It's a 3D spline that connects the ends of two curves.

    3D fit spline fits a 3D spline through a series of points. Think of it as a smoother version of connect-the-dots.
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    SledDriverSledDriver Member Posts: 116 ✭✭✭
    Yes I know that! My point is that the resulting curves are perhaps not as pure/predictable as could be.

    I'm also struggling with the fact that we have these controls such as Magnitude which are totally undefined to the user. Just a number. In engineering, it would seem that we need more understanding of what these numbers mean.

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    SledDriverSledDriver Member Posts: 116 ✭✭✭
    Many thanks for your detailed reply. All very interesting.

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    philip_thomasphilip_thomas Member, Moderator, Onshape Employees, Developers Posts: 1,381
    @SledDriver ^^^^ knowledgeable and detailed because Paul wrote the code! :)
    Philip Thomas - Onshape
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