Spatial and temporal frequency in animated mimic displays

Abstract

Animated mimic displays provide analogical representations of the flow of information or resources between system components. For example, the transfer of fuel from one tank to another in an aeroplane could be represented by fluid running through the connecting pipe, rather than an analogue meter or digital display. The quality of apparent motion is critical: does the subjective impression of flow that results from viewing the display correspond to the physical rate of flow that exists in the underlying domain? Previous research has revealed potential problems with display configurations modelled on prominent examples in the literature, including ambiguity with respect to both the direction and the rate of flow. Two psychophysical experiments were conducted to (1) investigate these potential problems more thoroughly and (2) examine two critical design parameters. Observers performed a rate-matching task with various combinations of spatial frequency, temporal frequency and luminance contrast. The findings were atypical: the usual ‘bandpass’ pattern (better performance at intermediate frequencies, relative to high or low frequencies) was obtained only for spatial frequency, and only when luminance contrast was low. In addition, performance was more closely tied to specific combinations of spatial and temporal frequency than to velocity. An interpretation based on Fourier's theorem is discussed and alternative display designs are proposed. Finally, design guidelines for spatial and temporal frequency are provided.