EWS correction not available in local refinement


Currently on the fly correction for the curvature of the Ewald sphere is available in NU-refine, but not in local refinement.

Would it be possible to add it to local refinement?

Obviously it will not be useful if a small local region is masked, but there are cases (e.g. pseudosymmetry) where it is desirable to perform local refinement with a global mask, and in such cases EWS correction would be be helpful.



Noticed this yesterday evening and was going to post this morning…!


Hi all,

We’ve added this to our roadmap :slight_smile:

In the meantime, note that Ewald Sphere correction can be applied to any particle stack (e.g. outputs of local refinement) by using the Homogeneous Reconstruction Only job. The only difference between this job and running Ewald Sphere correction in Non-Uniform refinement is that Non-Uniform refinement will reconstruct with marginalization enabled by default, whereas Homogeneous Reconstruction Only does not do marginalization. Marginalization usually has been observed to increase the FSC curve values, so that could cause a discrepancy between the outputs of Local Refinement and Homogeneous Reconstruction Only.

When implementing Ewald Sphere correction, we observed that accounting for Ewald Sphere curvature during particle alignment doesn’t make a discernible difference, which is why we didn’t push to add it to every job type. However, it makes sense to do this given the note about marginalization, so it’s on the roadmap!