Hi friend, Thanks for you kindly answer. But maybe I didn't make my origin question clear. Let me explain it. According to the chimera documentation, "Origin index refers to the grid indices of the XYZ origin "(http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/volumeviewer/volume...). But the origin I mentioned before actually refers to the origin of the map. And apparently they are different, So I want to know where can I obtain "the origin of the map" instead of the origin index. Hope to hear from you very soon. Yuhong Lee ________________________________ 发件人： Tom Goddard <goddard@sonic.net> 收件人： Yuhong Li <leon1991@yahoo.cn> 抄送： "chimera-users@cgl.ucsf.edu" <chimera-users@cgl.ucsf.edu> 发送日期： 2012年5月3日, 星期四, 上午 2:01 主题: Re: [Chimera-users] About resolution and origin 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#s... 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