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'[EE] Circuits for detecting looking?'
2006\08\28@212858 by Peter Todd

picon face
On Sun, Aug 27, 2006 at 04:35:58PM -0400, David VanHorn wrote:
> >
> >
> > There's an idea for you Peter, take a traditional clock and replace the
> > motor with a stepper. Have it work normally keeping time but
> > periodically "go nuts" backwards, fast forward etc, then correct itself
> > and behave for a random period.That might sell..
> > :)   D
>
>
> A PIR detector could be used to detect when you were really in front of it
> "watching" so as to prevent the behaviour during those times, but allow it
> to go nuts when nobody's all that close to it.

That's a pretty cool idea! Actually a friend of mine made an art peice
using a similar concept, she built various types of playground
equipment, see-saw, swing and one of those merry-go-round things, and
all made them activate and move while you were busy reading her artists
statement. They stopped the second you moved away to look at the work.

In practice of course, standing near the work, but looking away, still
kept the PIR sensor going... So...

How would you go about detecting the someone's gaze?

Personally I'd rig up a digital camera, with "eye-detecting" software,
but surely there are better ways...

--
http://www.petertodd.ca

2006\08\29@032911 by Vasile Surducan

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On 8/29/06, Peter Todd <spam_OUTpeteTakeThisOuTspampetertodd.ca> wrote:
{Quote hidden}

Any PIR sensor is based on a fresnel lense. There are two or three
types of lenses every of them specific for the PIR destination. there
are "courtain" lenses, "gallery" lenses and "volumetric" lenses.

1. Is very easy to modify any of these by keeping active just the part
of the lense which is in front of the art masterpiece. There are three
rows of fresnel areas on any PIR. Use a piece of paper cutted in the
center and put it inside the PIR package on the lense area so only one
fresnel area should be transparent for the PIR sensor.

2. The other choice is to modify the gain of the PIR amplifier so the
sensitivity will decrease but the whole sensed area remains active.

In both suggested versions (better combine one and two)  you'll be
able to create a PIR sensor with active area of about 2 meters (lowest
row of fresnel, volumetric lense) and just one direction of sensing.

greetings,
Vasile




>
> How would you go about detecting the someone's gaze?
>
> Personally I'd rig up a digital camera, with "eye-detecting" software,
> but surely there are better ways...
>
> --
> http://www.petertodd.ca
> -

2006\08\29@120727 by Bob Axtell

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Peter Todd wrote:
{Quote hidden}

The problem is that most very sensitive PIR detectors/algorithms work
when the warm object is MOVING.
You might need to design your own (all of mine were quite sensitive
(40m), but required the target to move
every few seconds or so.


--Bob

2006\08\29@124334 by Vasile Surducan

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On 8/29/06, Bob Axtell <.....engineerKILLspamspam@spam@neomailbox.com> wrote:
{Quote hidden}

What if you have a thermal noise like a radiator in front of it ?

but required the target to move
> every few seconds or so.


Put a mechanical chopper in front of the PIR detector and the subject
can stay...
easy, isn't it ?

greetings,
Vasile

2006\08\29@132709 by Bob Axtell

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Vasile Surducan wrote:
{Quote hidden}

yep, that works.
> greetings,
> Vasile
>  

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