Maybe now I find the answer to my own question, the command combinations molmap onGrid and vop resample can solve my problem. 

Zhihai 
On Jan 22, 2016, at 9:00 PM, 李智海 <21620101152414@STU.XMU.EDU.CN> wrote:

Hi,

Here I want to calculate a model-to-map FSC curve. If I am not wrong, firstly I am supposed to convert the pdb file to a density map. So I was just wondering in Chimera, how to use command molmap to generated a map with the same pixel size and dimensions as the corresponding map?

Any help will be high appreciated.

Best,

Zhihai Li