we've all seen these cool-looking light patterns created from shining
photons through tori and such. Is it possible to design an object to
give a desired light pattern, such as readable letters?

I've always wanted to be able to do this. After seeing povrays results
when using photons i got excited thinking it's very possible to reverse
what it does to decide where the photons go, to come up with something
to say what the object should be like.

what are your thought? im/possible un/cool

James

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"James Foster" <J.R### [at] durhamacuk> wrote:
["reverse photoning"]

> what are your thought? im/possible un/cool
>
- not completely impossible...

- cool if you figure the objects out by yourself ...



--
Jan Walzer <jan### [at] lzernet>

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James Foster wrote:
>[...] such as readable letters?

Glass text (maybe with some normal to make the caustics look cooler)?

--
Jonathan.

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Blob a 2d array of convex and/or concave lenses to generate a pattern of 
caustics that corresponds to an image. Keep in mind that it will have a 
mean focal point so the projection surface needs to be in parallel to the 
lens array, unless you get clever and graduate the focal points of the 
lenses so that the array has a skewed projection.

This could be a Macro?

James Foster wrote:

> we've all seen these cool-looking light patterns created from shining
> photons through tori and such. Is it possible to design an object to
> give a desired light pattern, such as readable letters?
> 
> I've always wanted to be able to do this. After seeing povrays results
> when using photons i got excited thinking it's very possible to reverse
> what it does to decide where the photons go, to come up with something
> to say what the object should be like.
> 
> what are your thought? im/possible un/cool
> 
> James

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That's not what i mean at all, i mean a single object which when light is
shone through creates a pattern of light which is readable.

rest y'all know what i mean!

JRG wrote:

> James Foster wrote:
> >[...] such as readable letters?
>
> Glass text (maybe with some normal to make the caustics look cooler)?
>
> --
> Jonathan.

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I'm positive that more than one object, each with different topology, would
be able to produce the same light effect. It's still difficult to find just
one of them.

I just had a thought (some of you out there probably already had) Daniel i
think this is what you were trying to say...

If you have a lense and it projects a dense circle of light (from a source
behind it) onto a plane, then get a second lense and stick it next to the
first, it too will produce a dense circle of light on the plane, now rotatle
the second one to place it's bright patch where you want it relative to the
first. And Repeat. build up a pattern of dots which can be read.

This would be the first step!! Then we just need to reduce it down and Blob
it (as Daniel Said)

Daniel Matthews wrote:

> Blob a 2d array of convex and/or concave lenses to generate a pattern of
> caustics that corresponds to an image. Keep in mind that it will have a
> mean focal point so the projection surface needs to be in parallel to the
> lens array, unless you get clever and graduate the focal points of the
> lenses so that the array has a skewed projection.

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You might be able to create a box with an bump map using an image of
text to control the photons.
Just a thought. I'll play with it myself, but I don't have much luck
with photons.

Josh English
eng### [at] spiritonecom

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Cool!
My first thought was to use reflection and no object for a Text object. All
you'd have to do is inverse every letter.
 Then I said to my self  'Hey I've played around with these in POV3.1' Before
POV had PHOTONS I made a macro that would calculate the reflection of any
polygon to a plane on the y=0 plane.'  I never use in a full scene. What you
talked about would be the reverse of that macro.
 You've gave me some ideas that I can play around with now.

James Foster wrote:

> we've all seen these cool-looking light patterns created from shining
> photons through tori and such. Is it possible to design an object to
> give a desired light pattern, such as readable letters?
>
> I've always wanted to be able to do this. After seeing povrays results
> when using photons i got excited thinking it's very possible to reverse
> what it does to decide where the photons go, to come up with something
> to say what the object should be like.
>
> what are your thought? im/possible un/cool
>
> James

--
Have Fun!

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James Foster wrote:
> 
> we've all seen these cool-looking light patterns created from shining
> photons through tori and such. Is it possible to design an object to
> give a desired light pattern, such as readable letters?
> 
> I've always wanted to be able to do this. After seeing povrays results
> when using photons i got excited thinking it's very possible to reverse
> what it does to decide where the photons go, to come up with something
> to say what the object should be like.
> 
> what are your thought? im/possible un/cool

It _is_ possible and it is done. It is called crystallography.
It is used to reconstruct crystals from scattered photons (real
ones...) But it is not easy and sometimes ambiguous. 

Markus

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Markus Becker wrote in message <3BFA5465.85FD234B@aicoss.de>...
>It _is_ possible and it is done. It is called crystallography.
>It is used to reconstruct crystals from scattered photons (real
>ones...) But it is not easy and sometimes ambiguous.


The ambiguity doesn't matter for this application.  After all, what's wanted
is *a* pattern that will produce the desired photon scatter, not the one
that *did* produce it.

--
Mark

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