Downsampling symmetry expanded particles


When downsampling symmetry expanded particles (e.g. for 3D-VA), cryosparc downsamples each symmetry expanded “copy” of each particle separately. This takes a lot of time and n-times the disk space (and scratch space in subsequent operations).

Would it be possible to not do this, and just downsample the original copy of each particle and take care of the symmetry expansion internally?


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Hi @olibclarke,

This is a good idea - adding to our tracker.
In the meantime, is it possible to work around this by

  • use particle set tools to intersect the final symmetry expanded particle set and the original (pre-expansion) set - this will yield only particle in the final set that are from the first symmetry position
  • downsample those particle
  • re-apply symmetry expansion
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I’m not sure that will work - if we want to apply 3D-VA to sym expanded particles after local refinement, won’t we then lose the refined angles for those that are not in the first sym position? Or maybe we can add the alignments.3D blob back after?