Le 20/05/2014 07:19, s.day a écrit :
> "Eriban" <pov### [at] spamgourmetcom> wrote:
>> Hi,
>>
>> It's been a while since I had some time and inspiration to create something in
>> POV-Ray, but I had a bit of both recently. Here's the result, which I hope you
>> like.
>>
>> Cheers,
>> Erwin
> 
> Very good, I understand how someone can draw something like this but to model it
> in POV... I have no idea how that could be done.
> 
> Sean
> 

Make it a T-shirt... or a corporate logo !

Actually, wonderful on a black T-shirt, need a white background for
printed logo, but not sure it remains as lovely.

It remind me of Escher, but of different kind.

>
http://www.4-construction.com/fr/magazine/images/formes-geometriques-dans-les-peintures-de-mc-escher_7539/12345/

The gear could be the next General Motors' or any steel/mechanic-related
company.

Or even a TV channel.

-- 
Just because nobody complains does not mean all parachutes are perfect.

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On 19-5-2014 21:26, Eriban wrote:
> Hi,
>
> It's been a while since I had some time and inspiration to create something in
> POV-Ray, but I had a bit of both recently. Here's the result, which I hope you
> like.

You truly are a 3D Escherian. Very well done indeed. And beautiful too.

Thomas

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Thanks for all your comments. Please find my replies below.

Stephen <mca### [at] aolcom> wrote:
> That is nice. I've not seen that one before.
> :-D

It's indeed far less common than the impossible triangle for example. However,
this illusion is not the first of its kind. See for example
http://im-possible.info/english/art/computer/ausbourne.html or
http://impossible-world.blogspot.nl/2014/03/impossible-cog-wheels.html. The
drawings on the latter page actually inspired this one.

Jim Henderson <nos### [at] nospamcom> wrote:
> Very nice, and a wonderful variation of the triangle (wasn't that Escher?) image.

Thanks. Escher indeed created drawings based on the impossible triangle,


> Now I want to know how it was done. ;)

The basic part of this illusion is quite straightforward to achieve. Two halfs
of the gear, oriented at right angles and placed such that they appear to line
up.

The devil is in the detail though. Given that the surface is reflective (and
also has a subtle normal) a few more tricks are needed to avoid discontinuities.
It's rendered in one go though, and did not require any post-processing.

"jhu" <nomail@nomail> wrote:
> That's unpossible!

Well, apparently not. Ray-tracers don't lie... ;-)

"s.day" <s.d### [at] uelacuk> wrote:
> Very good, I understand how someone can draw something like this but to model it
> in POV... I have no idea how that could be done.

Thanks. My above reply to Jim gives some insight on how to start. One of the
advantages of ray-tracing is that you have quite powerful tools at your
disposal: perfectly accurate object placement,  perfect mirrors, perfect copies
of objects, programmatic textures, etc. Those all really help when rendering
impossible objects.

Le_Forgeron <lef### [at] freefr> wrote:
> Actually, wonderful on a black T-shirt, need a white background for
> printed logo, but not sure it remains as lovely.

Might make a nice t-shirt indeed. The black background really helps to make the
object stand out, so best to leave that unchanged.

> It remind me of Escher, but of different kind.
>
> >
http://www.4-construction.com/fr/magazine/images/formes-geometriques-dans-les-peintures-de-mc-escher_7539/12345/

Yes, it's quite similar to the ribbons in Escher's "Cube with magic ribbons"
drawing. That one, however, is more advanced with bumps slowly morphing into
dents. Maybe I should give that a go as well sometime.

> The gear could be the next General Motors' or any steel/mechanic-related
> company.

It's a question though whether it then represents excellence, or shoddy
craftsmenship ;-)

Thomas de Groot <tho### [at] degrootorg> wrote:
> You truly are a 3D Escherian. Very well done indeed. And beautiful too.

Thanks. This is indeed becoming my ray-tracing specialty. The only thing I can
do reasonably well. Ah well, better that than doing many things poorly I
guess...

Cheers,
Erwin

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On Tue, 20 May 2014 16:36:50 -0400, Eriban wrote:

> The devil is in the detail though. Given that the surface is reflective
> (and also has a subtle normal) a few more tricks are needed to avoid
> discontinuities.

Indeed, I could see that this would make things really challenging.  You 
did a /fantastic/ job with lining things up and avoiding reflections that 
give it away. :)

Jim



-- 
"I learned long ago, never to wrestle with a pig. You get dirty, and 
besides, the pig likes it." - George Bernard Shaw

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Eriban wrote:

> Hi,
> 
> It's been a while since I had some time and inspiration to create
> something in POV-Ray, but I had a bit of both recently. Here's the result,
> which I hope you like.
> 
> Cheers,
> Erwin

I don't like it, I love it. It puts the impossible cube I did a while ago way to
shame.
-- 

Ger

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>Eriban  on date 19/05/2014 21.26 wrote:
> Hi,
>
> It's been a while since I had some time and inspiration to create something in
> POV-Ray, but I had a bit of both recently. Here's the result, which I hope you
> like.
>
> Cheers,
> Erwin
>
For impossible engines...
A fantastic shot!
;-)
Paolo

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Am 20.05.2014 22:36, schrieb Eriban:
> Thanks for all your comments. Please find my replies below.
>
> Stephen <mca### [at] aolcom> wrote:
>> That is nice. I've not seen that one before.
>> :-D
>
> It's indeed far less common than the impossible triangle for example. However,
> this illusion is not the first of its kind. See for example
> http://im-possible.info/english/art/computer/ausbourne.html or
> http://impossible-world.blogspot.nl/2014/03/impossible-cog-wheels.html. The
> drawings on the latter page actually inspired this one.

I think your version tops it though.

>> The gear could be the next General Motors' or any steel/mechanic-related
>> company.
>
> It's a question though whether it then represents excellence, or shoddy
> craftsmenship ;-)

Flexibility. It obviously represents the amalgamation of excellence and 
flexibility.

> Thomas de Groot <tho### [at] degrootorg> wrote:
>> You truly are a 3D Escherian. Very well done indeed. And beautiful too.
>
> Thanks. This is indeed becoming my ray-tracing specialty. The only thing I can
> do reasonably well. Ah well, better that than doing many things poorly I
> guess...

"reasonably well"? You must be an Englishman, as that's typical English 
understatement.

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Ger <No.### [at] ThankYou> wrote:
> I don't like it, I love it. It puts the impossible cube I did a while ago way to
shame.

Thanks. Well, an impossible cube is a good start. Hopefully this will inspire
you to try some more impossible scenes. They are fun! :-)

Paolo Gibellini <p.g### [at] gmailcom> wrote:
> For impossible engines...
> A fantastic shot!
> ;-)

Thanks!

clipka <ano### [at] anonymousorg> wrote:
> > It's indeed far less common than the impossible triangle for example. However,
> > this illusion is not the first of its kind. See for example
> > http://im-possible.info/english/art/computer/ausbourne.html or
> > http://impossible-world.blogspot.nl/2014/03/impossible-cog-wheels.html. The
> > drawings on the latter page actually inspired this one.
>
> I think your version tops it though.

Thanks.

> >> The gear could be the next General Motors' or any steel/mechanic-related
> >> company.
> >
> > It's a question though whether it then represents excellence, or shoddy
> > craftsmenship ;-)
>
> Flexibility. It obviously represents the amalgamation of excellence and
> flexibility.

Ah yes, that sounds better. So maybe it's a suitable logo for an Agile Hardware
company.

> "reasonably well"? You must be an Englishman, as that's typical English
> understatement.

Well, I am not English but did live there for a few years, so I might have
picked it up there.

Cheers,
Erwin

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"Eriban" <pov### [at] spamgourmetcom> wrote:
> Hi,
>
> It's been a while since I had some time and inspiration to create something in
> POV-Ray, but I had a bit of both recently. Here's the result, which I hope you
> like.
>
> Cheers,
> Erwin

You inspired me to try my hand at animating some of those. The html makes it all
tile.
Thanks,
Jeff

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Attachments:
Download 'geartile.zip' (181 KB)

"Jeff Reifel" <jef### [at] rocketmailcom> wrote:
> You inspired me to try my hand at animating some of those. The html makes it all
> tile.

Hi Jeff,

I really like this. I am surprised by how well it actually works, given the
awkward shape of the gears. Occasionally the gear teeth don't seem to fully
interlock, but there's some redundancy in your set-up, so it all keeps turning
nicely. At least, I have been watching it for a fair while now, and didn't see
any hiccups ;-)

Cheers,
Erwin

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