Performance of optical flow Barron, fleet and beauchemin JcV12:1,1994 http://www.csd.uwoca/faculty/barron/
Performance of Optical Flow Barron, Fleet and Beauchemin IJCV 12:1, 1994 http://www.csd.uwo.ca/faculty/barron/
Performance of optical flow Evaluation of different optical flow techniques Accuracy reliability density of measurements a common set of synthetic and real sequences Several optical flow methods Differential Matching Energy-based Phase-based
Performance of Optical Flow • Evaluation of different optical flow techniques – Accuracy, reliability, density of measurements • A common set of synthetic and real sequences • Several optical flow methods – Differential – Matching – Energy-based – Phase-based
Performance of optical flow Accurate and dense velocity measurement Accurate 2d motion filed estimation is ill posed Inherent differences between the 2d motion field and intensity variations Only qualitative information can be extracted
Performance of Optical Flow • Accurate and dense velocity measurement • Accurate 2d motion filed estimation is illposed – Inherent differences between the 2D motion field and intensity variations • Only qualitative information can be extracted
Optical flow Process · Three stages Perfiltering or smoothing with low-pass /band-pass filters in order to extract signal structure of interest enhance the signal-to-noise ratio Extraction of basic measurements Spatiotemporal derivatives Local correlation surface Integration of measurements to produce 2D flow field Often involves assumptions about the smoothness of the underlying flow field
Optical Flow Process • Three stages – Perfiltering or smoothing with low-pass/band-pass filters in order to • extract signal structure of interest • enhance the signal-to-noise ratio – Extraction of basic measurements • Spatiotemporal derivatives • Local correlation surface – Integration of measurements to produce 2D flow field • Often involves assumptions about the smoothness of the underlying flow field
Differential Techniques First-order derivatives and based on image translation /(x,t)=l(X-v1,0 Intensity Is conserved d(r, t) 0 t VI(x,1)v+1(x,)=0V/(x,)=(1(x,),(x1) Normal velocity s(x,) 1, (x, t) V(x, t) n=sn n(x VI(x, t)I
Differential Techniques • First-order derivatives and based on image translation • Intensity is conserved • Normal velocity I t I t ( , ) ( ,0) x x v = − ( , )T v = u v ( , ) 0 dI t dt = x ( , ) ( , ) 0 t + = I t I t x v x ( , ) ( ( , ), ( , ))T x y = I t I t I t x x x n v n = s ( , ) ( , ) ( , ) t I t s t I t − = x x x ( , ) ( , ) ( , ) t t I t = x n x x