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SUMMARY:You don't have to use 'motion energy' to compute velocity:  a biol
 ogically inspired and implemented motion model - Dr Linda Bowns\, Cambridg
 e Computational Biology Institute
DTSTART:20180509T120000Z
DTEND:20180509T130000Z
UID:TALK104167@talks.cam.ac.uk
CONTACT:John Mollon
DESCRIPTION:When humans (or robots) move through a scene\, the scene can b
 e represented as an optic flow (optical flow) field that contains vectors 
 representing all of the movement within the scene projected onto a two-dim
 ensional sensor. The movement may be caused by the agent moving through th
 e scene\, or by independent objects moving within the scene. A simultaneou
 s sample of these resulting vectors contain a good deal of information in 
 addition to object movement\, e.g. relative depth\; shape of objects\; or 
 signatures of specific biological motion. A general model of motion estima
 tion of this field would therefore be valuable. Previous reported attempts
  at computing motion estimation models have been dominated by the machine 
 vision community. However these attempts are not specifically concerned wi
 th biologically plausibility. Here\, the author presents a model of motion
  estimation that computes motion based on filtering the moving image into 
 sinusoidal responses varying in spatial frequency and orientation similar 
 to the early visual responses found in human vision. Unlike similar spatio
 -temporal energy models ``motion energy'' is not computed. The model is ma
 thematically explicit and simulated in MATLAB. It has been tested using ov
 er 7000 synthetic moving images with known veridical velocity (ground trut
 h). These images range from sparse translating patterns containing 1 to 10
 000 random pixels\, to dense narrow band sinusoidal patterns. Simulation r
 esults show that the model correctly estimates motion trajectories between
  90\\% - 100\\% angular direction error\, and displacement error (within +
 /- 1 pixel). The results remain robust at different contrasts. In addition
 \, explanations for a number of psychophysical and physiological results t
 hat emerge from the model are presented.\n
LOCATION:Kenneth Craik Room\, Craik-Marshall Building\, Downing Site
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