Continuous Rotation Angles Measurement Using Video Frame Images

A digital video is composed of a series of frame images. The continuous rotation angles are computed using the frame images grabbed from the rotation angle measurement video. An angle is calculated with the cosine theorem through the center point, start point and object point in a frame image and is compensated to a rotation angle. The positions of the object point in frame images are different during the period of the lasting rotation. The object point in a frame image is automatically detected with the computation of the correlation coefficients in every points of the rotation disk. The method described in this paper is successfully applied to determine the butterfly's flying direction. Experimental results reveal that the method plays an important role in the non-damaged and non-contact inspections and the instantaneous rotation angles measurement.