Gradient - based optical flow for sub-pixel registration of speckle image sequences using a spatial/temporal postprocessing technique

Digital image processing techniques are becoming a popular way of determining strains and full-field displacements in experimental mechanics due to advancements in image processing techniques and also because of the non intrusive way in which these measurements are done compared to traditional sensor based methods. This paper presents a polar component filtering technique for the image displacement fields in which two filters are used: a Kalman filter for temporal smoothing of the motion vector angles and a subsequent adaptive spatial filter for filtering both previously processed angles and amplitudes of the vectors.