## pymol-users

 [PyMOL] Principal Axes of Rotation From: Sean Law - 2009-06-02 22:41:59 Attachments: Message as HTML ```Hi, For the past couple of days I've been trying to find a way to rotate an object in order to show a front and side profile for publication. However, rotating with respect to the x, y, or z axes does not produce the correct result (even after moving the center-of-mass of the structure to the origin). What I need is a way to determine the principal axes of rotation for a given selection so that rotation about any one of these axes does not produce a "wobble" effect. I've even tried drawing a rectangular box around the object and then drawing an axes through the centroids of opposing faces but I still see wobbling. I've basically exhausted all of my attempts at this problem. Any help or suggestions would be greatly appreciated. Sean _________________________________________________________________ Create a cool, new character for your Windows Live™ Messenger. http://go.microsoft.com/?linkid=9656621```
 Re: [PyMOL] Principal Axes of Rotation From: gilleain torrance - 2009-06-03 10:02:08 ```Hi, I might be wrong, but might it be that you need the axis through the structure that minimises the distance of all the points to it. Or, to put it another way, the least-square-plane through the structure, the normal to that plane, and a thir axis perpendicular to both. If this is the case, you are in luck, as I already made such a thing: http://pymolwiki.org/index.php/Bounding_Box this script was designed to make a minimal bounding box (not just an axis-aligned one). I think that it does this, although my geometry is not good enough to know if I am right. Anyway, you already mention joining opposite faces of the box - well just use the axes calculated half-way through the first function. Hope this helps. gilleain On Tue, Jun 2, 2009 at 11:41 PM, Sean Law wrote: > Hi, > > For the past couple of days I've been trying to find a way to rotate an > object in order to show a front and side profile for publication.  However, > rotating with respect to the x, y, or z axes does not produce the correct > result (even after moving the center-of-mass of the structure to the > origin).  What I need is a way to determine the principal axes of rotation > for a given selection so that rotation about any one of these axes does not > produce a "wobble" effect.  I've even tried drawing a rectangular box around > the object and then drawing an axes through the centroids of opposing faces > but I still see wobbling.  I've basically exhausted all of my attempts at > this problem. > > Any help or suggestions would be greatly appreciated. > > Sean > > ________________________________ > Create a cool, new character for your Windows Live™ Messenger. Check it out > ------------------------------------------------------------------------------ > OpenSolaris 2009.06 is a cutting edge operating system for enterprises > looking to deploy the next generation of Solaris that includes the latest > innovations from Sun and the OpenSource community. Download a copy and > enjoy capabilities such as Networking, Storage and Virtualization. > Go to: http://p.sf.net/sfu/opensolaris-get > _______________________________________________ > PyMOL-users mailing list (PyMOL-users@...) > Info Page: https://lists.sourceforge.net/lists/listinfo/pymol-users > Archives: http://www.mail-archive.com/pymol-users@... > ```