> Given almost infinite time, what you'll probably end up with is a
> large amount of small objects, each taking a pixel (or several), which
> will only make sense when looking from a specific point in 3D space.
> You can do that with a single iteration so why bother? :)

Certainly true if only one perspective is used. Sorry, I wasn't clear... I
was considering using at least 3 photos of the same object under similar
lighting conditions taken ideally at equal intervals around the object and
comparing all of them to the model...

The original idea for this was effectively a poor mans digitiser using an
algorithm to make up for not being able to afford to build proper sensing
equipment, with the hope of arriving at a more 'real looking' model of a
complex object that would otherwise be practical...

Thanks for the input, :)

Luke

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On Wed, 30 Jan 2002 00:03:55 -0000, Luke Church wrote:
>> Given almost infinite time, what you'll probably end up with is a
>> large amount of small objects, each taking a pixel (or several), which
>> will only make sense when looking from a specific point in 3D space.
>> You can do that with a single iteration so why bother? :)
> 
> Certainly true if only one perspective is used. Sorry, I wasn't clear... I
> was considering using at least 3 photos of the same object under similar
> lighting conditions taken ideally at equal intervals around the object and
> comparing all of them to the model...

You could still converge to disjoint clouds of particles, each of which only
appears in one of the three (or whatever) views of the scene.

-- 
plane{-z,-3normal{crackle scale.2#local a=5;#while(a)warp{repeat x flip x}rotate
z*60#local a=a-1;#end translate-9*x}pigment{rgb 1}}light_source{-9red 1rotate 60
*z}light_source{-9rgb y rotate-z*60}light_source{9-z*18rgb z}text{ttf"arial.ttf"
"RP".01,0translate-<.6,.4,.02>pigment{bozo}}light_source{-z*3rgb-.2}//Ron Parker

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In article <slr### [at] fwicom>,
 Ron Parker <ron### [at] povrayorg> wrote:

> You could still converge to disjoint clouds of particles, each of which only
> appears in one of the three (or whatever) views of the scene.

That might actually be quite interesting...sort of an abstract sculpture 
with an actual point. It might be worth making something that does 
this...not a POV script, but a separate program that does a bunch of 
renders with scanlining or some other technique to figure out the 
information and then outputs the data, either as particles or voxel 
data. It could save every 100th frame or so, and might produce results 
within a reasonable period of time...

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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A lot of work has already been done with generating 3d geometry from 
multiple 2d images using techniques such as structured light.
http://www.prip.tuwien.ac.at/Research/3DVision/struct.html


Luke Church wrote:

>> Given almost infinite time, what you'll probably end up with is a
>> large amount of small objects, each taking a pixel (or several), which
>> will only make sense when looking from a specific point in 3D space.
>> You can do that with a single iteration so why bother? :)
> 
> Certainly true if only one perspective is used. Sorry, I wasn't clear... I
> was considering using at least 3 photos of the same object under similar
> lighting conditions taken ideally at equal intervals around the object and
> comparing all of them to the model...
> 
> The original idea for this was effectively a poor mans digitiser using an
> algorithm to make up for not being able to afford to build proper sensing
> equipment, with the hope of arriving at a more 'real looking' model of a
> complex object that would otherwise be practical...
> 
> Thanks for the input, :)
> 
> Luke

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On Wed, 30 Jan 2002 00:03:55 -0000, "Luke Church"
<luk### [at] hotmailcom> wrote:

>Certainly true if only one perspective is used. Sorry, I wasn't clear... I
>was considering using at least 3 photos of the same object under similar
>lighting conditions taken ideally at equal intervals around the object and
>comparing all of them to the model...

Ah, image reconstruction... there's a lot of info on that on the net.
For now, given almost infinite time, stick with this scenario:

1. Make a prism or cone with its vertex at location and its base
extending about as much beyond look_at. Have it pass through a pixel
of the image and be of approximately the same visual size.

2. Repeat for all pixels

3. Union all those cones

4. Repeat 1-3 for all viewpoints

5. Intersect all those unions

6. Grow old waiting :)


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

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Ron Parker writes:
> You could still converge to disjoint clouds of particles, each of which only
> appears in one of the three (or whatever) views of the scene.

Applying a penalty to the "fitness" of the generated images which
increases as the number of objects increases might avoid that.  Large
render times could also be penalised.  Of course, that may increase
the number of iterations required.

Rohan

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Ron Parker wrote:
> You could still converge to disjoint clouds of particles, each of which only
> appears in one of the three (or whatever) views of the scene.

But you can solve that just by using more reference photos. Might look
kewl anyhow!

-- 
signature{
  "Grey Knight" contact{ email "gre### [at] yahoocom" }
  site_of_week{ url "http://digilander.iol.it/jrgpov" }
}

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Not so weird, use a genetic algorithm and remember to write a fitness 
function which in some way ranks better less complex solutions (otherwise 
you really end with a sphere for each voxel...).

By the way, it is a really interesting project!

Bye!!!
        Alessandro Coppo
        a.c### [at] REMOVEiolit

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Ok everyone,

I think that I'll give it a go and see what happens... I'll keep you'll
posted when it comes out as beta. (Hopefully)

If anyone wants to know how it's going or has any further ideas to offer
feel free to email me or post somewhere round here, though I expect the
process to be slow, as I don't have a lot of spare time.

(Or more likely I'll be back asking for help)

BTW, a non-technical idea... Would it be possible to hold a database of
ideas currently in development in the Pov Community, so that information and
ideas could be shared and people might not 'waste' their time redeveloping
things that have already been developed or are in development... More than
once I begun developing an mini-app only to find about half way through that
someone else realises a version of it! My suggestion is a bit like perhaps a
micro-source forge, but without the hosting capability to save money...

Many thanks for your opinions,

Regards,

Luke

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Grey Knight wrote:
> 
> Ron Parker wrote:
> > You could still converge to disjoint clouds of particles, each of
> > which only appears in one of the three (or whatever) views of the
> > scene.
> 
> But you can solve that just by using more reference photos. Might look
> kewl anyhow!

In fact, you might be able to *force* this behaviour by using an actual
image for one reference, and noise for the other two. Ta-da!
Instant(well, nearly) abstract sculpture thingy!

-- 
signature{
  "Grey Knight" contact{ email "gre### [at] yahoocom" }
  site_of_week{ url "http://digilander.iol.it/jrgpov" }
}

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