Bob Hughes wrote:
> 
> "Tor Olav Kristensen" <tor### [at] hotmailcom> wrote in message
> news:393983D3.C3E17676@hotmail.com...
>
> | Did you use the same technique ?
> 
> Overlapping 'radial' patterns of black lines rotated a bit differently over a
> background plane of 'bozo' or other patterns.  Of course variations were
> tried, like bright lines, etc. later on when the subject came up again.

Interesting. But I don't understand how 
the "bozo" pattern comes in useful.

Isn't that a kind of random pattern ?


> I'd say your technique makes for a more true moire pattern.

I have never seen a definition Moire patterns.
Have you ?


> | Stupid question but what is "zonk" ?
> | (I was too young in the 70's :)
> 
> I would define it as what the sound might be if you heard one when first
> seeing it, but I don't really know the origin.  Ever seen Star Trek (TV) where
> they had a display near Spock's control panel which was a couple sets of
> radial lines rotated one over the other.  Same thing.  Guess they had that
> effect in the '60s too.

Sorry. I haven't seen Star Trek either. 
Just small fractions of different episodes.

But I can imagine that it was a cool film 
"trick" back then.


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

Post a reply to this message

| Interesting. But I don't understand how
| the "bozo" pattern comes in useful.
|
| Isn't that a kind of random pattern ?

Yes.  Only as backdrop behind the interference pattern created by the lines.
Anything could go behind them, even a whole scene :-)  Don't think too much
into it and you'll understand.

| > I'd say your technique makes for a more true moire pattern.
|
| I have never seen a definition Moire patterns.
| Have you ?


an independent usually shimmering pattern seen when two geometrically regular
patterns (as two sets of parallel lines or two halftone screens) are
superimposed esp. at an acute angle

How's that?  :-)

Bob

Post a reply to this message

Groovy.

Eric
--------------------
http://www.datasync.com/~ericfree
--------------------
"I don't like it, and I'm sorry I ever had anything to do with it."
- Erwin Schrodinger talking about Quantum Mechanics.

Post a reply to this message

On Sun, 04 Jun 2000 03:39:18 +0200, Tor Olav Kristensen
<tor### [at] hotmailcom> wrote:

>I have never seen a definition Moire patterns.
>Have you ?

A Moire pattern is an interference pattern resulting from
superimposing two or more grids with close parameters. To answer your
question about vibrational analysis, a French guy named Moire found
this phenomenon when introducing vibrations into fine sand-covered
glass plate by means of a violin bow.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

Post a reply to this message

Tor Olav Kristensen wrote:
> 
> Strange. If so, I wonder how it is applied.

You project a stripe pattern onto an object. You take
a CCD-Image of this pattern. Then you "stress" the object
(put pressure in/onto it or whatever), project the same
pattern on it and take another picture. You overlay
those picture and you get a moiree pattern that you can
analyse.

Also useful in Speckle interferometry.

(http://www.google.com) and search for speckle interferometry
and/or moiree analysis.

Markus

Post a reply to this message

Bob Hughes wrote:

> Don't think too much into it and you'll understand.

Hehe.

=)



> an independent usually shimmering pattern seen when two geometrically regular
> patterns (as two sets of parallel lines or two halftone screens) are
> superimposed esp. at an acute angle
>
> How's that?  :-)

That's nice to know. Thank you !


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

Post a reply to this message

Peter Popov wrote:

> A Moire pattern is an interference pattern resulting from
> superimposing two or more grids with close parameters.

So then there are many possible "types" of Moire patterns !
I wonder if there are any 3D Moire patterns


> To answer your question about vibrational analysis, a
> French guy named Moire found this phenomenon when
> introducing vibrations into fine sand-covered glass plate
> by means of a violin bow.

Doesn't this mean that this phenomenon also is related to
minima and maxima of standing waves ?

Wouldn't standing waves in a patterned "3D-medium(s)"
then generate 3D Moire patterns ?


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

Post a reply to this message

Eric Freeman wrote:

> Groovy.

Thanks.

Btw: I found some nice moving grooves:

http://www.sandlotscience.com/Moire/moire_2.htm
http://www.sandlotscience.com/Moire/moire_1.htm
http://math.hws.edu/xJava/other/Moire1.html

Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

Post a reply to this message

Markus Becker wrote:

> Tor Olav Kristensen wrote:
> >
> > Strange. If so, I wonder how it is applied.
>
> You project a stripe pattern onto an object. You take
> a CCD-Image of this pattern. Then you "stress" the object
> (put pressure in/onto it or whatever), project the same
> pattern on it and take another picture. You overlay
> those picture and you get a moiree pattern that you can
> analyse.

So from the co-ordinates where the two sets of stripes cross,
one can deduct information about how the material has
moved/deformed in that region ?

This leads me to think about the nice coloured patterns
that appear when one shines polarized light through stressed
acrylic materials and then views this through a polarized filter.

I did a search for photoelasticy and got this hit:
http://www.britannica.com/bcom/eb/article/1/0,5716,61311+1,00.html

(I did not know that Britannica now is available on the net. :)


And of coarse then I had to look up Moire in Brittanica,
and then I found this:
http://www.britannica.com/bcom/eb/article/5/0,5716,54535+1+53206,00.html

(Here they also mention other useful applications for the Moire
patterns.)


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

Post a reply to this message

Tor Olav Kristensen wrote:
> 
> So from the co-ordinates where the two sets of stripes cross,
> one can deduct information about how the material has
> moved/deformed in that region ?

Right, but I think usually the reulsting image is processed
in such a way that is is smoothed (blurred) so that no
individual lines appear but only bright and dark stripes
(i.e. the moiree is the only information that remains).

> This leads me to think about the nice coloured patterns
> that appear when one shines polarized light through stressed
> acrylic materials and then views this through a polarized filter.

It's a similar effect, both have to do with interference.

Markus

Post a reply to this message