Out-of-plane tilt angle range vs. restraint

[Carsten Sachse]

Dear Luca,

On Dec 23, 2014, at 13:45, Luca Galbusera wrote:

Dear Sachse,

I would like to ask you a question about how segmentrefine3D works. 

I don't understand the difference between the parameter "LR/MR/HR/MaxR out-of-plane search restraint" and the parameter "Out-of-plane tilt angle range”. 

Looking at the source, I see that "Out-of-plane tilt angle range" it's used to produce different tilting projections of the reference volume, but the parameter "out-of-plane search restraint" seems to be used only in the function that estimates the total space required.

Also, in your paper about spring you say that "by default the refinement projects 90 projections around the helical axis and assumes seven possible out-of-plane titlt angles from -12 to 12 degrees. [...] The out of plane tilt step follows an even distribution between 0 and the maximum tilt angle". Thus it seems to confirm that the parameter "Out-of-plane tilt angle range" is used to obtain the projections form the reference.

The difference between the two parameters:

1. Out-of-plane tilt angle range is the absolute search range you assume your helices have, e.g. from -12 to 12 degrees out of the plane.

2. Out-of-plane search restraint refers to the search range in comparison relative to a starting parameter. Therefore, in the low and medium-resolution there are no restraints (i.e. 180 degrees). To save computational effort at high and maximum-resolution stages to search within 6 and 2 degrees is sufficient. 180 degree on its own does not make too much sense considering the out-of-plane tilt but it makes sense together with the azimuthal restraint.

Best wishes,

Carsten

Thank you

Kind regards

Luca Galbusera