Alt-BEAM Archive
Message #08469
To: beam@sgiblab.sgi.com beam@sgiblab.sgi.com
From: Bruce Robinson Bruce_Robinson@telus.net
Date: Monday, 20 December 1999 5:37
Subject: Re: Lets Hypothesise...
>Richard Caudle wrote:
>>
>>>
>>> If any of this was true, then we would all have
>>> one eye and one ear. The truth is that distance
>>> is quite an important factor in navigating our
>>> world. We have two eyes and two ears so we can
>>> triangulate distances.
>
>>
>> Pish, Posh! The single eye/ear thing would work
>> in a two dimensional world, but we happen to be
>> in a three dimensional world. It's go nothing to
>> do with triangulation. We have to percieve objects
>> in a three dimensional space. The only time distance
>> enters into the formula is when we are making a
>> conscious effort to determine distance. Besides, I
>> thought that triangulation took three points, not two.
>>
>> Prove me wrong.
>
>Sorry, Richard. He's right -- almost. Our two ears primarily give us
>direction. Experience (e.g. knowledge of thunder) and volume give us an
>approximate idea of distance. Blind people do much better, using
>relative volume, echoes, and vast experience.
>
>Our eyes triangulate. Triangulation involves 3 measurements to define
>the dimensions of a triangle. The measurements can be 3 points, 3
>distances, 3 angles, or a combination thereof. In the case of vision,
>it's two angles of the eyeballs, plus the distance between them.
>
>And with vision, we are always judging distances unconsciously. It's how
>I get the coffee in the cup first thing in the morning before my brain
>is in gear. It's how people can drive a car over a familiar winding road
>with no conscious awareness. And it's why my neighbour, with one
>artificial eye, never pours liquids into a container that's sitting on
>the counter -- he always puts his hand around the cup, glass, or
>container.
>
>And, by the way, most of the time, most of us live in a mainly
>two-dimensional world. We don't turn our eyes up to the sky often
>enough.
>
>Bruce
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