Hello. I am experiencing a strange problem with local refinement using downsized particles (after symmetry expansion in cryosparc). Basically the symptom is that although I got normal maps after homogeneous refinement, once I performed symmetry expansion and refined the particles locally I got maps that looked overrefined with very discontinuous density and high background noise.
Here are a little bit more details:
- I tried to downscale particles either in Relion by rescaling while re-extracting particles, or in cyropsarc with its “downscale particles” job. Both approaches give the same result.
- I tried to refine both with and without non-uniform option, but it didn’t make a different.
- I also tried to limit the maximum align resolution to 4 A, but it didn’t help.
Is there any trick to prevent this from happening?
Thank you very much,