[Chimera-users] vop add

Tom Goddard goddard at sonic.net
Wed Jan 14 14:50:51 PST 2015


Hi Francisco,

  If you average two maps with “vop add #0,1 scale 0.5,0.5” then where the maps do not overlap the density value will be reduced by averaging when one map has a point inside the structure and one map has the point outside.  Another approach to “merging” would be to take the maximum of the two maps with "vop maximum”. If you really want to average the maps where both are greater than some threshold density, but where only one is greater than the threshold you simply use that map’s value then you will get discontinuities in the merged map at the boundary where both maps are above the threshold.  So I wouldn’t recommend that but it could be done with “vop threshold” to make a 0/1 mask for each map where it is above threshold, add those two masks to get the number of map values (0, 1 or 2 for each grid point) then divide the sum of the maps by that map.  Oops, there is no "vop divide”, only a “vop multiply”.  I don’t think you want to do that, but if you do let me know and I will add a vop divide to divide one map by another point-wise.

	Tom


> On Jan 14, 2015, at 6:49 AM, Fco Javier Chichón wrote:
> 
> Dear all
> 
> I would like to merge several volumes.
> Not all the voxels of the two volumes fit, so when I used vop add command, Chimera add the densities instead of average them.
> 
> Anyone know how to do that?
> 
> Thanks
> 
> -- 
> =======================================================
> Francisco Javier Chichón García
> 
> Centro.: Centro Nacional de Biotecnología
> Dept.: Macromolecular Structure
> Lab.: S1-S0.1
> Tel.: (+34) 91585-5497:4690
> =======================================================
> 
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