Re: [R] is there a way to visualize 3D normal distributions?

From: Ben Bolker <>
Date: Fri 03 Feb 2006 - 09:55:47 EST

Michael wrote:
> shape3d only gives rigid sphere... not the free form ellipsoid that I
> want...

   one or the other of us is missing something.

    after running demo(shapes3d)
[to define ellipsoid3d] and rgl.clear(),

s1 <- ellipsoid3d(qmesh = TRUE, trans = diag(4)) shade3d(rotate3d(scale3d(s1, 1, 1, 2),

                  angle=pi/4, x=0, y=1, z=0),
         col = "red")


  produces an ellipsoid with radii (1,1,2) rotated by pi/4 around the y axis. I'm too lazy to figure out how to translate a variance-covariance matrix into a scaling/rotation matrix (the scale will want to be something like eigen(v)$values*qnorm(0.975) for a 95% contour, the rotation matrix is some function of the eigenvectors), but it seems to me that this will produce any ("free form"?) ellipsoid you want.

     Ben Bolker mailing list PLEASE do read the posting guide! Received on Fri Feb 03 10:05:45 2006

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