and
described
easily-obtainable
other=20
at=20
refractive=20
=20
reflection".
a=20
=20
=20
of=20
by=20
Alas, that does not mean that any of this (with the possible exception of bicycle reflectors) is currently readily available to pimpom (OP).
Pulsed drive of white LEDs?
Nov 22, 2009
65 Replies
JosephKK Inscribed thus:
There is always a reflective car number plate.
Best Regards:
Baron.
[snip]
Brings to mind another of the weird ideas I have...
How would you detect the PRESENCE of such a reflector? About 50' away, along about a 12' horizontal line, 2' to 4' off the ground. ...Jim Thompson
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
You can never be too prepared for the REPRESSION!
Good question ! The number plate recognition cameras seem to be able to do it, even in the dark.
Best Regards:
Baron.
I want the school bus driving up to ring my doorbell ;-)
They have yellow bicycle-style reflectors down the sides. ...Jim Thompson
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
You can never be too prepared for the REPRESSION!
Sheer speculation:
- Take a (digital) photo under ambient-light conditions
- Fire a flash, and take a second digital photo while the flash is illuminating the field of view.
- Normalize each photo-image, so that the average values of the two images are the same.
- Compare the two images (masking off portions known to be near to the lens and not of interest) and look for areas where there is a substantial amount of brightening in the second image. It seems to me that the difference between ambient and flash-lit scenes will be much greater for retroreflectors, than for objects with a diffuse or specular reflection characteristic.
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
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