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A look at motion in the frequency domainA moving image can be specified by a contrast distribution, c(x,y,t), over the dimensions of space x,y, and time t. Alternatively, it can be specified by the distribution C(u,v,w) over spatial frequency u,v and temporal frequency w. The frequency representation of a moving image is shown to have a characteristic form. This permits two useful observations. The first is that the apparent smoothness of time-sampled moving images (apparent motion) can be explained by the filtering action of the human visual system. This leads to the following formula for the required update rate for time-sampled displays. W(c)=W(l)+ru(l) where w(c) is the required update rate in Hz, W(l) is the limit of human temporal resolution in Hz, r is the velocity of the moving image in degrees/sec, and u(l) is the limit of human spatial resolution in cycles/deg. The second observation is that it is possible to construct a linear sensor that responds to images moving in a particular direction. The sensor is derived and its properties are discussed.
Document ID
19830015902
Document Type
Technical Memorandum (TM)
Authors
Watson, A. B. (NASA Ames Research Center Moffett Field, CA, United States)
Ahumada, A. J., Jr. (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
September 4, 2013
Publication Date
April 1, 1983
Subject Category
BEHAVIORAL SCIENCES
Report/Patent Number
A-9304
NAS 1.15:84352
NASA-TM-84352
Funding Number(s)
PROJECT: RTOP 505-35-31
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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