   Axis Angle to Quaternion (when angle = 0)
  Hi all! I'm little confused - to convert axis and angle to quaternion, we can use this simple formula:qx = ax * sin(angle/2)qy = ay * sin(angle/2)qz = az * sin(angle/2)qw = cos(angle/2)But, when angle = 0 the result will be always 0, 0, 0, 1, no matter how axis looks. Is there any solution to compute quaternion with 0 angle?Thanks for any suggestions!   
  If you have angle == 0, why should it be wrong, if the quaternion represents the identity? If you don't rotate, about ANY axis, then the result IS IN FACT the identity... (no matter what the axis is!)   ;  I can see where the confusion is coming from. Axis and angle here means rotation around that axis not a unit vector representing the orientation + a "roll" value.So if the angle is 0 it means no rotation.   