Hi Yuhong,

I don't know what kind of map you have. If it is a single-particle electron microscope reconstruction, then the most common way to determine resolution is Fourier shell correlation. The original 2-d micrographs are divided into two sets and two 3-d maps are computed and then you see how far out in frequency the maps agree. Chimera does not do 3-d reconstructions so this would have to be done before analysis in Chimera. In the Chimera Fit in Map dialog it will suggest a default resolution under Options "Use simulated map from atoms at resolution...". The default is 3 times the grid plane spacing. Often the map grid spacing is chosen to be about 1/3 the resolution -- a level of oversampling that provides nicer visualization.

I don't understand your origin question. Maybe you mean how do you find the center of symmetry of a symmetric map. The measure symmetry command can do that. For example, "measure symmetry #0" if your map is model #0. Here is documentation.

http://www.cgl.ucsf.edu/chimera/current/docs/UsersGuide/midas/measure.html#symmetry

Tom

Hi friends,

Firstly, I was wondering how to know the resolution of my map since one day I opened volume viewer...tools...fit to segments. And I found that there displaying "density map resolution". So my question is whether that number is the correct resolution of my map?

Secondly, in the volume viewer...corrdinates I can know the origin index, but how can I know the origin?

These questions may seem to be stupid, but I just want to know. So hope to hear from you very soon!

Best Wishes,

Yuhong Lee