Thanks, I'm just reasoning things out. Considering having a pair of opto-sensors, 4 meters apart, off on sidewalk. Those could make pulses that you then decode. At 30 meters per second, those two impulses from car motion would be some 100 milli-seconds apart, but also containing info, by which sensor got the (shadow) first.
For example, the classic 'falling edge' for the left side sensor, would be a 'zero', currently, with a 'one' state just recently; That along with a rising edge, on the right side sensor, (similar pattern of older=0, current=1),
that's makes for 2 compelling arguments, to conclude that motion from left to right just occurred.
My point about the 4 bits, 2 of a new input, 1 from each digital sensor, and then another 2 a saved older copy, is that, combinatorially, there are exactly 16 ways that can happen.
Of course, with bigger inputs, that number gets colossal pretty fast. Just with 4 corners, and 2 older copies (shifted), that's 12 bits..., So that's 4096 variations that would need to be checked, if MANUAL pre- determinations are done.
Oh, and also it's the case, where each point relates to 11 others, in space and in the back-time copies, so that there's A LOT of ambiguous patterns, that aren't clearly confused, but don't perfectly indicate some outcome, in this case, some perfectly indicated direction of travel.
Plus, most real-life sensing has the input pulses overlapping, in time.
As for 'POOLING', I've done an approximation, just by dropping half of the sensors, although losing some data. You probably can appreciate, having TWO sensing elements, allows some (crude) estimate, of motion object's speed, at least in terms like:
'Moving slow to left direction'.
I'm also thinking about, using weights after the first stages are digital (digital output from sensors).