Glennerster A, Fitzgibbon A W, Hansard M E, 2000, "Calibrated direction of heading" Perception 29 ECVP Abstract Supplement
Calibrated direction of heading
A Glennerster, A W Fitzgibbon, M E Hansard
It has long been assumed that the visual system analyses retinal flow by decomposing it into rotational and translational flow (Longuet-Higgins and Prazdny, 1980 Proceedings of the Royal Society, Series B 208 385 - 397), where translational flow specifies heading direction. For a fixating observer, rotational and translational flow are tightly linked to one another, suggesting alternative heuristics may be used.
Here we show how the following information can be computed, with increasing levels of precision. For a set of translations in the base plane (containing the fixation point and the translating optic centre): (i) divide the translations into two groups with respect to the fixation point, for example 'left' and 'right'; (ii) recover the component of translation perpendicular to the line of sight up to some unknown scale factor (k1) and the component along the line of sight up to a different scale factor (k2); and (iii) recover the ratio k1:k2 , providing a fully calibrated estimate of the directions of heading. Two elements of this scheme support it as a biologically plausible hypothesis. First, it is valuable if the observer maintains fixation on a point as (s)he moves. Second, there are intermediate stages, each providing useful information.
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