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>At 09:08 AM 1/20/98 -0800, Rick Dickinson
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>>Place triggerable xenon flash units behind IR filters every 10 feet along
>>both long walls.  Place IR sensors every foot or so along both long walls.
>>Trigger each flash in sequence, recording which sensors do *not* see which
>>flashes.  Lines drawn between flashes and the sensors "in the dark" will
>>intersect the target.  Simple algebra calculates intersection point for
>>each pair of readings.
>
>Interesting, and I thought about it (I'm prone to brute force solutions).
But since we need x/y info, these sensors (or beams) would have to be
placed at the short _and_ the long walls, which would make it a bit
cost-prohibitive. Also, the ground is sloping.
>
>To answer you questionnaire:
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>>What are the details of the space?
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>It's a yard. Fences on both sides, one side waterfront (and hence wide
open to intruders).
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>>Is it enclosed by walls on all four sides?
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>Fences on long sides, house on short side, wazterfront at the end.
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>>Can equipment/sensors/etc. be mounted anywhere along the perimeter?
>Sure, within limits.
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>>How about within the space?
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>No.
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>>Is the space empty, or are there obstacles that would cause "blind spots"?
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>More or less empty. But trees are growing. There's a pool. People tend to
set up pool furniture in summer. Shrubbery grows. You get the picture.
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>
>>What resolution is needed -- how accurately does one need to locate the
>>target?
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>For a good close-up shot ... I figure 1ft
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>>Is it possible to mount some sort of device to the target?  (Not likely, as
>>you mentioned security, but I thought I'd ask...)
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>No :)
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>BS
>