[Chimera-users] Gaussian filter prior to fitmap?

[Oliver Clarke]

Hi,

Would it be possible to add an option to fitmap (in either/both chimera/chimerax) to restrict the spatial frequencies used for fitting? That is, to fit gaussian filtered versions of the input maps behind the scenes, but apply the resulting transform to the unfiltered maps? Filtering maps to say 15 Å gives a much better radius of convergence in my experience - much less prone to getting stuck in local minima.

In general I also wish that when applying a gaussian filter in Chimera (or chimerax), the approximate equivalent in spatial frequency terms was indicated - e.g. if I am applying a gaussian filter of sdev x to a map of pixel size y, what lowpass filter does this effectively equate to?

Also, when one wants to fit multiple maps to a single reference (quite common when inspecting results of 3D classification), Chimera gives an error message indicating that multiple maps have been input. There is an “eachmodel true” option one can set to allow fitting of multiple maps to a single reference, but the default value is false. It seems to me that the default value for this should be true, as if the user is specifying a wildcard or model ID range for the maps to fit, this is probably the behavior they are after I think. Or maybe the error message could be altered to indicate that if this is what one wants to do the eachmodel keyword needs to be specified?

Cheers
Oli