Difference between optical flow field and motion field? I have been trying to understand the various confusing definitions of optical flow field and motion flow field but cannot wrap my head around it.
Some authors use the term interchangeably other give specific examples where the two are different.For example in case of a rotating barber's poll as 
given here.  
How are the two fields so different?

Actually, this is in the context of motion estimation for a project that I am doing.I really don't get how motion estimation is different from optical flow estimation and the difference between optical flow field and 2d motion field.Please help me understand these.
well, have you ever seen a rotating barber's poll?

It looks like the stripes are moving up (optical flow), but of course the motion of the thing is a rotation in the horizontal plane.



The rationale really is that the optical flow is based on how the image changes. And if you just compared two frames from the animation above, you'd clearly say that the blue stripe moved upwards. However, if you'd open the device and looked inside, you'd see the motor that causes the mechanical movement (rotation).