I want to estimate Helical parameter ( Helical Rise, Twist, asymmetric sub unit, per turn  ) of Tau filament for Reference Module generation using Chimera. Is it possible to estimate from raw micrographs or 2D Class Average  by Chimera? 

I was wondering if any of you can provide me procedure if any, will be a great help. Eagerly waiting for your reply.

Thanks in Advance, 

Reja