Meaning of particle scale and scale factor

Features and Functionality
1

Hi,

I’m new to cryosparc.And I can’t understand the meaning of ‘scale’.Is this scale is the orientation scale or other meaning.Is there some explanation.Thanks very much.

shuai

2

In cryoSPARC, the (Fourier space) image formation model for particle i:

Ii = ai * Ci * Pi(V)

where ai is the scale parameter, Ci is the CTF, Pi is the projection operator, and V is the reference volume.

So the “particle scales” are effectively a contrast scalar or particle weight. The original publication SI doesn’t say exactly how/when the scales are optimized, perhaps @apunjani can comment.