Hi Steinar,
This parameter is used to put priors on the angles. You're right that by
default the center of the prior changes from one iteration to the next.
You can change this by explicitly providing rlnAngleRotPrior (&Tilt/Psi
too!) in the input STAR file. Thereby, the center of the prior will be
kept fixed at that angle. The angles are searched +/- 3 sigma_ang values,
but with a Gaussian fall-off in prior probability. You could therefore
perhaps set the prior to 7.5 degrees?
HTH,
Sjors
> Dear all
>
>
> I've been trying to figure out how the --sigma_ang flag (or --sigma_rot,
> tilt and psi) is used to chose which angles are used for 3D refinement in
> RELION.
> So far I haven't come across it in literature or documentation for (maybe
> it has and I've completely missed it...). So I thought my best choice was
> just to ask here. How does it work?
> If I want to run a refinement and restrict my angles +-15 deg, can this be
> done? I suspect the answer is 'not quite' since it seems this parameter is
> adaptive and changes over the course of the refinement.
>
>
> Many thanks,
>
> Steinar
>
>
> Rosenthal lab
>
> The Francis Crick Institute
>
>
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--
Sjors Scheres
MRC Laboratory of Molecular Biology
Francis Crick Avenue, Cambridge Biomedical Campus
Cambridge CB2 0QH, U.K.
tel: +44 (0)1223 267061
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