I am looking for a way to "measure" the rotational symmetry of a 2-dimensional vector field.
For example, a rotating vector field with the same center as the frame is "symmetric" as in the following image. On the other hand, if the center is off from the center of the frame, or if some of the vectors have a snaky orbit that is not a regular circle, it can be said to be "not symmetric".
The above definition may be intuitive and ambiguous, but in any case, as far as I know, there are studies that "detect" rotational symmetry, but there are no studies that "measure" it. Is there an indicator like in the example above, where the measure in the former case is 0 and the measure in the latter case is 1? If anyone knows, I would appreciate it if you could share it. Or if there is any mathematical uncertainty in this question, that is still fine. Being able to implement the algorithm is also important in this question.