I am running a local refinement in cryoSPARC 4.2.1, with ‘Optimize per-particle scale’ activated. It seems to help a lot, the resulting density is at higher resolution and looks reasonable.
The problem is that after a few iterations, I get this message in the log: Rescaling optimal scales and reconstruction result to preserve median 1.0. Rescaling factor is nan
After this, the density disappears and the reconstruction just produces empty boxes:
Refining scales does seem unstable in local refinement.
I don’t have a solution to this really, but I wonder if you kill your job after it has done a couple of iterations (before it becomes unstable) and mark it as complete, if you could then use the output particles for a round of local refinement with fixed scales (using the scales you have already refined)?