Is Rot and Trans Entangled With Id and/or Exp? Where is 0,0,0 ?

[jimydavis]

Referring to this other issue: #9

My interpretation of the jitter is that the rotation and translation are entangled with def compute_shape(self, alpha_id, alpha_exp): . I notice that trans in z-direction has sudden variations against the previous frame during an eye blink. And I am assuming eye blinks are either alpha_id + alpha_exp or just alpha_exp only.

Q0: What is the potential entanglement?
Q1: If my application is to perform reasonably smooth video tracking, what do you suggest I do? Just take a moving window average across frames for both trans + exp + id?
Q2: Is the 0,0,0 origin (which trans is supposed to be relative against) the standard one of BFM2009? Could you kindly point me to any documentation on this?

Thank you for your guidance. Any help is deeply appreciated.