Computer Laboratory

Technical reports

A new method for estimating optical flow

W.F. Clocksin

November 1997, 20 pages

Abstract

Accurate and high density estimation of optical flow vectors in an image sequence is accomplished by a method that estimates the velocity distribution function for small overlapping regions of the image. Because the distribution is multimodal, the method can accurately estimate the change in velocity near motion contrast borders. Large spatiotemporal support without sacrificing spatial resolution is a feature of the method, so it is not necessary to smooth the resulting flow vectors in a subsequent operation, and there is a certain degree of resistance to aperture and aliasing effects. Spatial support also provides for the accurate estimation of long-range displacements, and subpixel accuracy is achieved by a simple weighted mean near the mode of the velocity distribution function.

The method is demonstrated using image sequences obtained from the analysis of ceramic and metal materials under stress. The performance of the system under degenerate conditions is also analysed to provide insight into the behaviour of optical flow methods in general.

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BibTeX record

@TechReport{UCAM-CL-TR-436,
  author =	 {Clocksin, W.F.},
  title = 	 {{A new method for estimating optical flow}},
  year = 	 1997,
  month = 	 nov,
  url = 	 {http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-436.pdf},
  institution =  {University of Cambridge, Computer Laboratory},
  number = 	 {UCAM-CL-TR-436}
}