Hi Hernando, I could not reproduce this problem. As an example I fetched EDS (2fo-fc) 1a0m and PDB 1a0m. The map is #0 and the atomic structure #1. Using Volume Viewer menu Features... Coordinates shows that the map's voxel size is 0.37 0.37 0.36719 Then I try command: molmap #1 6.0 The molmap map's voxel size from that command is 2. Then I try command: molmap #1 6.0 onGrid #0 The molmap map's voxel size from that command is 0.37 0.37 0.36719 which is correct for the #0 grid. Tested in Chimera version 1.17.3 ... there is also a new release 1.18 that I haven't downloaded yet (I mostly use ChimeraX now), but I don't expect any difference. If you have a current version of Chimera but still keep having this problem, you can use Help... Report a Bug but we would need details of how to reproduce the problem, which may include specific data. Make sure that what you think is the voxel size agrees with what Chimera thinks is the voxel size. I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco

On Jul 18, 2024, at 9:44 AM, Hernando J Sosa via Chimera-users <chimera-users@cgl.ucsf.edu> wrote:

Dear Chimera

I am using the molmap command with the option onGrid but the results are not what I would have expected.

With a loaded map (#0) and an atomic model(#1)

The command:

molmap #1 6.0 onGrid #0

generates a map with a voxel size of 6.768 even though the loaded map #0 has a voxel size of 0.846

Trying to force the voxel size with

molmap #1 6.0 onGrid #0 gridSpacing 0.846

produces the same result as the onGrid option overrides the gridSpacing option.

How can I produce a map using molmap that has exactly the same dimensions and voxel size of map #0?

Thanks

H.