Sunday, May 20, 2007

Frames Per Second in birds

I had occasion to visit Hardin Ridge yesterday for the International Migratory Bird Day celebrations. They had several stations, and it was fun for the kids, but one thing I thought was interesting was during a presentation on birds of prey. They displayed a peregrine falcon and talked about its remarkable vision; here's what Steiner has to say about it:

They are equipped with full-color vision and with eyes specially adapted to permit rapid adjustment of focus while moving at speed, and from four to eight times the resolving power of the human eye. Hovering may be compared to looking into a field from a car moving at twenty miles an hour or from one which comes to a standstill every few yards. It would be possible for a human being to see an individual rabbit or large game bird at a range of 600-700-yards; a bird of prey, with about four times the resolving power of the human eye, should therefore be able to see it at a range of nearly two miles.

What particularly caught my attention, though, was when they said that the peregrine can perceive significantly more events per second than humans can. I don't know if it's exactly the same concept, but I assume we're talking about frame rate here; they commented that even when cameras have been attached to these birds as they make one of their amazing, 200 miles-per-hour dives onto some unsuspecting pigeon, all humans can see is blur.

Now, the frame rates they mentioned seemed surprisingly low to me they suggested 18-20 events per second for humans and maybe two or three times that amount for the birds. But I suppose it's an example of flicker, and syncing, where if you perceive the wrong couple of frames in a videogame the action seems all wrong, or maybe the afterimage in the eye causes the slowdown.

So I'm not sure where all this is leading, except maybe that a really cool videogame would be Peregrine: The Stoop for a Pigeon. But I suspect there's a lot of basic science to be done before any game can simulate the visual experience of this amazing animal.

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