Hi Damien, I attached a file that you can open directly in Chimera (File... Open) to show red, yellow, and blue arrows pointing along the X, Y, and Z axes, respectively. The file simply contains the following 9 lines of text: .translate 0.0 0.0 0.0 .scale 5 .sphere 0 0 0 0.5 .color red .arrow 0 0 0 5 0 0 .color yellow .arrow 0 0 0 0 5 0 .color blue .arrow 0 0 0 0 0 5 You could change the origin in the ".translate" line and the scale in the ".scale" line. This simple format for describing geometric objects is described here: <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/bild.html> You can apply the rotation/translation of one model to another (put one model in the reference frame of another) with the command "matrixcopy": <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/matrixcopy.html> So, if you have opened the arrows as model 6 and you want them to show the frame of reference of model 3, you would use the command: matrixcopy 3 6 You would use the same approach to put any type of model (not just the arrows model) in the same frame of reference as another model. I don't think there is a default reference frame of Chimera -- it may depend on the command. (Others, please correct me if I'm wrong!) For some commands, the default is the "laboratory" frame of reference, where X is horizontal in the plane of the screen, Y vertical in the plane of the screen, Z perpendicular to the screen. I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco On Nov 14, 2009, at 3:12 AM, Damien Larivière wrote:
Hi Tom, Thank you very very much for this solution! It works perfectly. I have two other questions:
Is is possible in Chimera to display a reference frame? if yes, can we display the default one of the software or the one of a 3D structure?
Also, can we modify the reference frame attached to a 3D structure so that it possible to align it with the default reference frame of the software?
My best regards Damien