Hi Kyle, It seems all would depend on the definition of local. Maybe you can mask or volume-erase or vop zone (around your current marker) to remove or zero the parts that you consider to be nonlocal, then measure center of mass of the resulting map? I don’t know how well that would work, however. Related links: <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/measure.html#center> <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/mask.html> <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/vop.html#zone> <http://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/voleraser/voleraser.html> I was also thinking about some kind of filtering or binning (e.g. other vop options), but that might reveal a low-res maximum rather than a center of mass. 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 Mar 16, 2016, at 1:45 PM, Morris, Kyle <Kyle.Morris@warwick.ac.uk> wrote:

Dear Chimera dev and community,

If I have approximately placed a marker into my volume density, is there a way to recentre this marker according to the centre of mass of the local density rather than the centre of mass of the whole volume?

Many thanks for your help!

Best wishes, Kyle