Dear developers, I am trying to compare the center of mass of multiple cryo-EM maps and models. The receptor is the same in all cases, just the ligand bound in the binding pocket varies. I want to show a directionality to how the ligands are binding in the pocket between the structures, so I have aligned the maps and models together and am attempting to run "measure center" and "measure inertia" to initiate this comparison. However, when I run these commands, the output markers and ellipsoids are not positioned in an aligned fashion as their parent objects, but rather in there initial positions before alignment, which is not useful for comparisons of the subtle movements between structures. Additionally, if I could get the measurements to work on the aligned structures, is there a tool in ChimeraX that would allow me to draw vectors from a reference point to the center of masses? Furthermore, is center of mass the correct parameter for comparison of densities that are variable in shape? (e.g. comparing the relative position of a long and flat density to a short a globular density?) Thank you! Sincerely, -- Kevin C. Felt PhD Candidate - Chakrapani Lab Department of Physiology and Biophysics School of Medicine Case Western Reserve University