detect the centerline of 3D data points

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Penny 2017-12-8

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评论： ng 2019-8-20

Hello, everyone. I am trying to detect the centerline of a set of 3D points. These 3D points are plotted and the figure is attached.

Does anybody know how to detect the centerline of these 3D data points. The equation of this centerline may be z = k1*x+k2*y+b; The coordinates of the 3D points are stored in X, Y, Z.

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Matt J 2017-12-8

Do the points lie on the surface of a circular cylinder, or some more general surface?

Penny 2017-12-8

Yes, the points lie on the surface of a circular cylinder. But not a regular cylinder

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Matt J 2017-12-8

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编辑：Matt J 2017-12-8

在 MATLAB Online 中打开

If the parametric equations for the line is L(t)=m+t*d, the following should give a good estimate of m and d, as long as the sampling of the surface is uniformly distributed,

A=[X(:),Y(:),Z(:)];
 m=mean(A,1).';
 A=A-m.';
   [~,~,V]=svd(A,0);
    d=V(:,1);

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Matt J 2019-8-20

编辑：Matt J 2019-8-20

I am beginning to think it could be because the top and bottom edges of the cylinder are not perpendicular to the expected axis which is why there is the slight angle.

That would definitely contribute, but even more generally than that, we don't expect exact results when fitting noisy data.

ng 2019-8-20