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Subject: Rotate 3D object to align with xy plane From: Greg Date: 26 Apr, 2011 20:36:05 Message: 1 of 9 
Hi  I realize this is an old thread but I have a perhaps more explicit question. I have three points given in xyz coordinates. Obviously they are coplanar. Assume the origin is at the center of gravity of the three points. I wish to rotate the points such that the rotated points are in a plane parallel to the xy plane, ie z=0 plane. I seek a rotation operator that will apply this rotation to any set of points, and the inverse operator, to rotate back. I am not concerned with rotation about the z axis  ie, any rotation that puts the three points in a plane parallel to xy, and with the same distances between the pairs of points, will do. 
Subject: Rotate 3D object to align with xy plane From: Doug Schwarz Date: 26 Apr, 2011 21:27:20 Message: 2 of 9 
On 4/26/2011 4:36 PM, Greg wrote: 
Subject: Rotate 3D object to align with xy plane From: Roger Stafford Date: 27 Apr, 2011 15:34:04 Message: 3 of 9 
"Greg " <gdgibbons@aol.com> wrote in message <ip7abl$p2g$1@fred.mathworks.com>... 
Subject: Rotate 3D object to align with xy plane From: Roger Stafford Date: 27 Apr, 2011 17:19:09 Message: 4 of 9 
"Roger Stafford" wrote in message <ip9d1c$29t$1@fred.mathworks.com>... 
Subject: Rotate 3D object to align with xy plane From: Saurabh Mahapatra Date: 28 Apr, 2011 00:55:21 Message: 5 of 9 
Something to ponderrigid body math tells me that if you give me any two snapshots or configurations of a rigid body(the way you have defined your norm constraints), then there are infinitely many "permutations" of rotations that can do the job of aligning with the xy plane (and some troubling consequence that the pairs of (x,y)s you will generate will be nonunique. So, you will have to define another constraint that limits these possibilities. 
Subject: Rotate 3D object to align with xy plane From: Matt J Date: 11 May, 2011 15:57:08 Message: 6 of 9 
"Roger Stafford" wrote in message <ip9j6d$kmc$1@fred.mathworks.com>... 
Subject: Rotate 3D object to align with xy plane From: Roger Stafford Date: 11 May, 2011 18:27:02 Message: 7 of 9 
"Matt J" wrote in message <iqebkk$d1c$1@newscl01ah.mathworks.com>... 
Subject: Rotate 3D object to align with xy plane From: Matt J Date: 11 May, 2011 19:52:04 Message: 8 of 9 
"Roger Stafford" wrote in message <iqekdm$8hq$1@newscl01ah.mathworks.com>... 
Subject: Rotate 3D object to align with xy plane From: Roger Stafford Date: 11 May, 2011 20:57:04 Message: 9 of 9 
"Saurabh Mahapatra" wrote in message <ipadtp$gc8$1@fred.mathworks.com>... 
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