Dear Jianhao,
There is a slightly silly way.  The “vop add” command is really for adding multiple maps together, but I’ve noticed that if you only specify one map, it makes a copy of it.  For example, if I already have a map #0, command:

vop add #0

...makes another map #1 that is the same.  Its name includes “resampled” but the histogram looks identical.
I hope this helps,
Elaine
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Elaine C. Meng, Ph.D.
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco

> On Aug 23, 2017, at 9:25 PM, C.J. <biocjh@gmail.com> wrote:
>
> Dear specialists,
>
> Is there a command line to creat a model copy of a opened EM map in the window?
> Thank you!
>
> Best regards!
> Jianhao