Optical Camouflage
BottleBob
http://www.youtube.com/watch?v=JKPVQal851U
Is it trick? Or a trick? :)
And for metalworking content - How do you machine a brick you can't
see, eh?
--
BottleBob
http://home.earthlink.net/~bottlbob
Gunner Asch
wrote:
>To All:
>
>http://www.youtube.com/watch?v=JKPVQal851U
>
> Is it trick? Or a trick? :)
>
> And for metalworking content - How do you machine a brick you can't
>see, eh?
Very interesting. Sniper Wear!!
Cool!
Gunner
vinny
"sittingduck" <du...@spamherelots.com> wrote in message
news:Xns9D0B906652491du...@nomail.afraid.org...
> BottleBob wrote:
>
>> http://www.youtube.com/watch?v=JKPVQal851U
>>
>> Is it trick? Or a trick? :)
>>
>> And for metalworking content - How do you machine a brick you can't
>> see, eh?
>
> what it really is, when the answer is right there in the description....
> See sig. :D
>
Looks just like a guy standing in front of a projector, and things colored
white reflect back the movie. The mirror gives it away, things are slightly
shifted when he holds up the mirror.
Pretty damn cool none the less.
Eregon
news:Xns9D0B906652491du...@nomail.afraid.org:
> We have broken from reality--a psychotic Nation. Ignorance with a
> pretense of knowledge replacing wisdom. -- Ron Paul
The idiot should take his own advice instead of attempting to run for
congress once again.
Jon Elson
> To All:
>
> http://www.youtube.com/watch?v=JKPVQal851U
>
> Is it trick? Or a trick? :)
You wouldn't
even notice it on broadcast TV, they use it all
the time to paint
"studio sets" over plain furniture, TV weather
maps, etc.
All you need is an object with a color that
doesn't appear anywhere
else in the set, and the video switcher can be set
to substitute
video from a different source when it sees that
color. In this
case, they used an effects generator to memorize
the background
before the guy stepped in front of the camera.
When the camera
sees the key color, it switches to the memorized
background.
The first started doing this chroma key stuff
about 1965 or so, so
it is REALLY old TV technology.
Jon
Half-nutz
The Very first thing in the description is:
"Please read this before you comment"
It is NOT chroma keying.
Jon Elson
> The Very first thing in the description is:
> "Please read this before you comment"
>
> It is NOT chroma keying.
Well, unless I see a demo in person, with my naked eyes (well,
OK, I need glasses to see more than 6", but...) I am NOT going
to believe this at all! This gadget needs to grab photons from behind
the guy's head and send them on toward your eyes without altering their
path at all. I find it REALLY hard to believe such a device can exist
at all, and that it fits is a 4" sphere that the guy waves around.
It defies what I know of physics that he is doing this, so I require
a **LOT** more proof than a you-tube video!
If it is not strictly a chroma-key job, then it is effectively the
same thing, video mask cutting of the image.
Jon
Half-nutz
Yikes..
The background is a projection.
If he wears a reflective coat, then it reflects the projected image,
just like the projection screen behind him does.
And thus the shiny coat appears to be the background, and thus
invisible.
Even if he is front of a real background, there is a projector where
the view is from, projecting the background.
Again, his shiny/reflective coat is painted with the background.
Not a chroma key job. And not even quite the same thing.
You could be standing there, and observe the effect. No Way you look
at a green screen chroma key studio and see the finished result with
the naked eye.
How does that defy physics?
Pretty cool eh?
Wes
> And for metalworking content - How do you machine a brick you can't
>see, eh?
You hire a blind machinist.
Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller
Carla Fong
> Jon Elson wrote:
>
>> It defies what I know of physics that he is doing this, so I require
>> a **LOT** more proof than a you-tube video!
>
>> If it is not strictly a chroma-key job, then it is effectively the
>> same thing, video mask cutting of the image.
>
> He's using a projector.
>
We had a system (front projection) that did this when I was a studio
photographer in the late 1970's.
It consists of a large retroreflective screen behind the 'actor', and a
camera and projector in front of the 'actor'. (If you're not sure what
'retroreflective' is, think of the highway signs that seem to glow
brightly in the dark when illuminated by your headlights - it reflects
most of the incident light directly back along the axis of incidence. A
typical brand name is 'Scotchlite')
The camera and projector are arranged to be on exactly the same optical
centerline, usually by having a 'straight shot' for the camera and the
projected image is added in through a half-silvered mirror at right
angles to the camera lens axis.
The image from the projector is reflected back to the camera from the
retroreflective screen, and the screen is very high gain and directional
so it reflects mostly back along the incident axis.
The actor is carefully lit so the incident light does not swamp out the
reflective screen image.
Anything in the scene that is supposed to look transparent is simply
made of retroreflective material - so the actor's coat, the ball and the
block are retroreflective and appear transparent because they are
reflecting the incident background image back to the camera.
See also <http://en.wikipedia.org/wiki/Front_projection_effect>
Carla
"Any sufficiently advanced technology is indistinguishable from magic."
Arthur C. Clarke
Jon Elson
> The background is a projection.
> If he wears a reflective coat, then it reflects the projected image,
> just like the projection screen behind him does.
> And thus the shiny coat appears to be the background, and thus
> invisible.
> Even if he is front of a real background, there is a projector where
> the view is from, projecting the background.
> Again, his shiny/reflective coat is painted with the background.
>
> Not a chroma key job. And not even quite the same thing.
> You could be standing there, and observe the effect. No Way you look
> at a green screen chroma key studio and see the finished result with
> the naked eye.
OK, so the ball is maybe painted with the glass bead stuff they put
on highway signs, so it reflects really well back toward the light
source? That's pretty simple, and has a similar effect when viewed
from a single vantage point. A true "cloaking device" would show
whatever was behind the ball, so if you moved your head, the view would
change, like looking through a window. This trick would not work that
way, you'd just get the same projected view.
Jon