[Chimera-users] Calculating and showing the Mass center of Volume Segments

[Tom Goddard]

Hi Claudius,

   My previous script to place a marker and the volume center of mass 
had a bug as you noticed.  It placed the marker in the global coordinate 
system but calculated it in the volume coordinate system.  These are 
different if you move or rotate the view before using the script.

   Here's the fixed volumecenter.py script.  I changed a few lines at 
the end.  It now makes a new model for each center marker you create and 
the coordinates are correct.  You still need to choose the volume data 
set in the volume dialog before running the script.

     Tom


> Hello Tom,
>
> I'm very sorry to bother you again, but the Script only works fine if 
> I only load one map. As soon as I got another MRC loaded, it sets the 
> marker on absurd positions no matter what I selected in volume viewer 
> or anywhere else.
>
> With best regards
>
> Claudius
>
> *Von:*Tom Goddard [mailto:goddard at sonic.net]
> *Gesendet:* Dienstag, 15. November 2011 02:36
> *An:* Schmidt, Claudius
> *Cc:* 'chimera-users at cgl.ucsf.edu'
> *Betreff:* Re: [Chimera-users] Calculating and showing the Mass center 
> of Volume Segments
>
> Here is a Python script to place a marker at the center of mass of a 
> map at points above the displayed contour level.  You open your map 
> and then open the script (menu File / Open) to create the marker.  For 
> marking more than one map, just highlight the map in the volume dialog 
> by clicking on its histogram or name and open the script.  The grid 
> index of the center point will be reported in the reply log (menu 
> Favorites / Reply Log).
>
> I will make the Chimera "measure" command do this calculation and 
> marker placement in the future.  This is a busy month so it will be 
> some time before I get to that.
>
> I've attached the script and also put it on the Chimera Python scripts 
> web page:
>
> http://plato.cgl.ucsf.edu/trac/chimera/wiki/Scripts
>
>   Tom
>
>
>
> There isn't any Chimera command to identify the center of mass or a 
> density map or place a marker/atom there.  But that seems useful.  A 
> Python script can easily do it.  I'll see if I can give you a Python 
> script at the end of today, or maybe add an operation to the Chimera 
> "measure" command to do this job.
>
>     Tom
>
>
> Hello,
>
> I got a volume map that I segmented in 4 parts. Now I wanted to 
> measure how the parts are coordinated to each other. As the 
> Axes/Planes/Centroids menu can only create planes by atoms I wanted to 
> place atoms in the mass- center of each segment. Is there any way to 
> realize that?
>
> Or do you have any other way to measure the angles. To explain what 
> I'm trying to measure: Example you have 4 segments, I call them a b c 
> d. I want to measure how the axis that is formed by a and b, forms an 
> angle to c and d, or how ist he angle of the plane formed by a b and c 
> compared to ab and d . All for segments are basically the same objects 
> just turned and rotated.
>
> With best regards
>
> C. Schmidt
>
>
>
>
>
>
>
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