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<div class="moz-cite-prefix">John,<br>
<br>
Perhaps it goes without saying but it may not be obvious. The
reason traffic cones were chosen for the navigation targets, both
for the aging RoboMagellan contest from Seattle and the
RoboColumbus competition in Dallas, is not because they are
traffic cones, but because they are fluorescent orange. They were
chosen for their color, not the other way around.<br>
<br>
dpa<br>
<br>
<br>
<br>
On 12/05/2016 07:21 PM, David Anderson wrote:<br>
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<div class="moz-cite-prefix">John,<br>
<br>
Interesting post. Also great to see you out and about at the
last competition. And dinner. Robots + Mexican food ==
DoublePlusGoodness.<br>
<br>
I will start by saying that you, being by nature an inquisitive
and research-oriented kinda guy, should certainly be encouraged
to delve into this and find us a superior method of finding
colored objects, be they fluorescent orange or any other
color. By all means.<br>
<br>
But I think perhaps there is a misunderstanding here. You
wrote:<br>
<br>
"I think we have a conceit that orange is unique enough because
it looks dramatic to our eyes." <br>
<br>
Instead, fluorescent orange is used precisely because there is
otherwise so little of it naturally in the environment. The
software can be tuned to recognize any arbitrary color. But
most of those colors are present in copious amounts in nature.
Which makes the recognition task much harder. Not much
fluorescent orange in the average outdoor scene.<br>
<br>
The digital cameras we use are in fact most sensitive to light
in the infrared, because of the nature of the CCD tech. And
everything outdoors has a significant infrared signature because
of the nature of the illumination, i.e., the sun. As a result
all modern digital cameras, including the one in your phone as
well as those used by professional photographers, have an
infrared filter on the front end. Otherwise the infrared
swamps out everything else. (In fact if you want a camera that
can see into the infrared, to see heat and such, all you need to
do is remove that filter. There are hacks on the internet to
do that very thing.)<br>
<br>
The reason that fluorescent orange works so well with these
cameras is not because of human conceit, but rather because
there is so little of it naturally in the environment to confuse
the recognition algorithm. So the signal to noise ratio is
very high, and the likelihood of false detections is
commiserately low. <br>
<br>
In fact, this is true for all the fluorescent colors, not just
orange. <br>
<br>
The cameras and recognition algorithms we use work equally well
with fluorescent blue and fluorescent green. Again, because
there is so little else in the environment that are those
colors. ( Just kind of hard to find fluorescent blue and
fluorescent green traffic cones, though we could paint some
those colors if so desired.)<br>
<br>
In some early experiments I added a 1 million candle-power
flashlight to the robot in order to try to smooth out the wide
range of lighting differences in outdoor situations. But I
found after a lot of experimentation that it wasn't really
needed.<br>
<br>
As an aside, a biology professor once told me that the reason
that our eyes are optimized for "visible" light which, as you
point out, is less than an "ocatve" of the electromagnetic
spectrum, is because eyeballs evolved underwater, and indeed are
full of water, and water is transparent to those frequencies.
Birds and insects can also see into the ultraviolet, but
ultraviolet causes cancers, and only critters with short life
spans have that capability: they don't live long enough for the
cancers to be a problem. <br>
<br>
But as I say, if you can come up with a different type of sensor
or sensor plus illuminator that works better, bring it on!
We're all interested.<br>
<br>
cheers,<br>
dpa<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
On 12/05/2016 06:07 PM, John Swindle wrote:<br>
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cite="mid:158d1754cd7-5bd9-9628@webprd-m05.mail.aol.com"
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<div><font face="sans-serif">Dave Anderson and others,<br>
<br>
Some time back I asked why visible light cameras are used
to locate the traffic cones. I think the answers were that
such cameras are cheap, and something to the effect that
the color of the cone is notable.<br>
<br>
I don't think I made my point: As with sonar operating at
a frequency that we think is noise-free because we don't
hear all the interfering noise that exists above our
hearing, I think we have a conceit that orange is unique
enough because it looks dramatic to our eyes. But visible
light is such a tiny part of the usable spectrum. What I
was suggesting is that there might be a characteristic of
the cones that could be exploited to give fantastic
distinction to the cone's location, even if the exploit is
unique to the cones that are being used that day. The
exploit might require the robot to illuminate the cone.
(Or, shall I say, irradiate the cone? The group might find
that disturbing.)<br>
<br>
My comments are motivated by several things:<br>
<br>
. The problems of using visible light cameras to guide a
self-driving vehicle, where radar, LIDAR, and other
approaches are much more foolproof.<br>
<br>
. "Alternate light sources" cited in the forensic TV
shows. A fancy name for colored light and some
beyond-visible stuff.<br>
<br>
. Tricorders and ship's sensors.<br>
<br>
Later,</font><br>
John Swindle<br>
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