My input is x,y,z coordinates of some data points lying in a tilted plane. I am trying to find a way to compute the minimum radius circle enclosing these data.
I have looked at the minboundcircle(x,y,hullflag) here: http://www.mathworks.com/matlabcentral/fileexchange/34767-a-suite-of-minimal-bounding-objects
but it only works when the points are in the x-y plane. I know I can rotate and translate my points to bring them in x-y plane, but I am looking for an easier way.
I have also considered using convhulln() but it does not work, apparently because all my points are coplanar.
Any help is much appreciated.
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First, from your previous posts and this one I see that you're doing lots of stuff with 3d geometry. I think that you will find this FEX entry very very useful: http://www.mathworks.com/matlabcentral/fileexchange/24484
However, if I understand your problem correctly I think there's a simple answer. My understanding is that you have a set of planar points and you want to find the radius of a circle tilted to that plane that would enclose them.
If the points are indeed exactly coplanar, then a minimum bounding sphere of the points in 3D would actually have the same radius as the circle you describe.
In that case, let me point you towards: http://www.mathworks.com/matlabcentral/fileexchange/34767-a-suite-of-minimal-bounding-objects
It has a minboundsphere which would do the job.
If your points aren't exactly coplanar, then what you're actually talking about is a minimum bounding cylinder, tilted to align with the plane. In that case, I think that you'll find that the easiest way to answer the question is to:
The good news is that with geom3d it's actually very easy to do this. If you don't have your plane (but you know 3 points lying on that plane), you can get it by:
myPlane = createPlane(P1, P2, P3);
Then you can get local coordinates of those points by transforming them:
Tform = createBasisTransform3d('global', myPlane); PTS_WRT_PLANE = transformPoint3d(myPts, Tform);
At this point, your task of finding a minimum bounding circle gets quite a bit easier because we're only working in 2d. John D'Errico's suite of minimal-bounding-objects also has a minboundcircle.