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From: Tor Olav Kristensen
Subject: With and without a light_source - 2 attachments
Date: 24 Jun 2003 03:19:10
Message: <Xns93A4378303A9Ftorolavkhotmailcom@204.213.191.226>
The source code for one of the images below contains a light
source (and renders in less than a second), while the source
code for the other image does not have a light source (and
renders in about 3 seconds).

Both images were rendered in one single pass with the official
POV-Ray v3.5. No other tools or resources was used, (except for
jpeg-compression.)

So here is a little quiz: Can anyone guess how this was done ?

And which of the images has source code with light_source ?


Tor Olav


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Attachments:
Download 'A12.jpg' (13 KB)
Download 'A91.jpg' (13 KB)

Preview of image 'A12.jpg'
A12.jpg

Preview of image 'A91.jpg'
A91.jpg


 

From: B  Gimeno
Subject: Re: With and without a light_source - 2 attachments
Date: 24 Jun 2003 04:55:49
Message: <3ef7d9d5@news.povray.org>
"Tor Olav Kristensen" escribió:
>
> The source code for one of the images below contains a light
> source (and renders in less than a second), while the source
> code for the other image does not have a light source (and
> renders in about 3 seconds).

> So here is a little quiz: Can anyone guess how this was done ?

Once you've got the first image, just reuse it as image_map (in a box?) )
with ambient 1


> And which of the images has source code with light_source ?
>

I can't see any difference between them

Regards
Bruno Gimeno
eelr


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From: chaps
Subject: Re: With and without a light_source - 2 attachments
Date: 24 Jun 2003 12:15:15
Message: <3ef840d3$1@news.povray.org>
There is a tiny difference, You can see it in attached file :oP

Chaps

"B. Gimeno" <nos### [at] jazzfreecom> wrote in message
news:3ef7d9d5@news.povray.org...
> "Tor Olav Kristensen" escribió:
> >
> > The source code for one of the images below contains a light
> > source (and renders in less than a second), while the source
> > code for the other image does not have a light source (and
> > renders in about 3 seconds).
>
> > So here is a little quiz: Can anyone guess how this was done ?
>
> Once you've got the first image, just reuse it as image_map (in a box?) )
> with ambient 1
>
>
> > And which of the images has source code with light_source ?
> >
>
> I can't see any difference between them
>
> Regards
> Bruno Gimeno
> eelr
>
>


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Attachments:
Download 'A12minusA91.jpg' (3 KB)

Preview of image 'A12minusA91.jpg'
A12minusA91.jpg


 

From: Tor Olav Kristensen
Subject: Re: With and without a light_source - 2 attachments
Date: 24 Jun 2003 12:26:29
Message: <Xns93A4945469AADtorolavkhotmailcom@204.213.191.226>
"B. Gimeno" <nos### [at] jazzfreecom> wrote in news:3ef7d9d5@news.povray.org:

> "Tor Olav Kristensen" escribió:
>>
>> The source code for one of the images below contains a light
>> source (and renders in less than a second), while the source
>> code for the other image does not have a light source (and
>> renders in about 3 seconds).
> 
>> So here is a little quiz: Can anyone guess how this was done ?
> 
> Once you've got the first image, just reuse it as image_map (in a box?) )
> with ambient 1

Nope, that's not the way I did it. No image maps were used.


>> And which of the images has source code with light_source ?
>>
> 
> I can't see any difference between them

As Chaps said; There is a tiny difference.
(It is easier to see it if you invert Chaps' difference image.)


Tor Olav


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From: Hugo Asm
Subject: Re: With and without a light_source - 2 attachments
Date: 24 Jun 2003 15:27:35
Message: <3ef86de7$1@news.povray.org>
Slope maps?

Regards,
Hugo


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From: Ross Litscher
Subject: Re: With and without a light_source - 2 attachments
Date: 24 Jun 2003 16:23:03
Message: <3ef87ae7@news.povray.org>
Tor Olav Kristensen <tor_olav_kCURLYAhotmail.com> wrote in message
>
> So here is a little quiz: Can anyone guess how this was done ?

no idea really. it migh tbe interesting, but if it takes longer without a
light source and the images are *almost* identical, what's the point? unless
the non light_source image produces nice shadows, which isn't evident here.

>
> And which of the images has source code with light_source ?

my guess is A12.jpg. it looked like the bright area on the inside was
tighter. but now looking again, they look too close.


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From: Tor Olav Kristensen
Subject: Re: With and without a light_source - 2 attachments - 2 attachments
Date: 24 Jun 2003 19:52:06
Message: <Xns93A4DFE02E17torolavkhotmailcom@204.213.191.226>
"Ross Litscher" <lit### [at] osuedu> wrote in
news:3ef87ae7@news.povray.org: 

> 
> Tor Olav Kristensen <tor_olav_kCURLYAhotmail.com> wrote in message
>>
>> So here is a little quiz: Can anyone guess how this was done ?
> 
> no idea really. it migh tbe interesting, but if it takes longer
> without a light source and the images are *almost* identical, what's
> the point? unless the non light_source image produces nice shadows,
> which isn't evident here. 

Actually, this "method" does not produce shadows at all.
(It therefore provides a way to use a shadowless light source
to make phong highlights for isosurfaces.)

The highlights in the texture are controlled by a function.
(I.e.: The highlights are kind of "built into" the texture.)

I made a macro that builds functions that can be used to
control texture maps, pigment maps, color maps etc. for
isosurface shapes.

One just have to tell the macro about the camera position,
the position of the "virtual" light source and the amount
of ambient, diffuse and specular (phong) reflection for the
surface. One can also tell the macro about how the light
is attenuated as it "moves" away from the light source.
(Of coarse, the macro also needs to know the function for
the isosurface shape itself.)

You can find attached 2 more images that were made with
this macro. The "virtual" light source has the same
position in space as in the other images. But the textures
in the texture_map are different.

I'm not sure yet if all this is useable for more than
generating special effects.


>> And which of the images has source code with light_source ?
> 
> my guess is A12.jpg. it looked like the bright area on the inside was
> tighter. but now looking again, they look too close.

A12.jpg is made with a "virtual" light source.


Tor Olav


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Attachments:
Download 'A14.jpg' (31 KB)
Download 'A15.jpg' (29 KB)

Preview of image 'A14.jpg'
A14.jpg

Preview of image 'A15.jpg'
A15.jpg


 

From: Tor Olav Kristensen
Subject: Re: With and without a light_source - 2 attachments
Date: 24 Jun 2003 20:00:35
Message: <Xns93A4E155BF1EBtorolavkhotmailcom@204.213.191.226>
"Hugo Asm" <hua### [at] post3teledk> wrote in news:3ef86de7$1@news.povray.org:

> Slope maps?

It all started with my experiments with slope maps for isosurfaces.

But: No it is not made with slope maps.

I used a function controlled texutre map to make the shading and
the phong highlights.

The function calculates (numerically) the slope of isosurfaces and
uses information about the directions to the camera and the light
source to calulate a value that I use to control the brightness of
the texture at each point on the isosurface.

Also see my answer to Ross Litscher some minutes ago in this thread.


Tor Olav


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From: Ross Litscher
Subject: Re: With and without a light_source - 2 attachments - 2 attachments
Date: 24 Jun 2003 22:16:46
Message: <3ef8cdce@news.povray.org>
Tor Olav Kristensen <tor_olav_kCURLYAhotmail.com> wrote in message
news:Xns### [at] 204213191226...
> "Ross Litscher" <lit### [at] osuedu> wrote in
> news:3ef87ae7@news.povray.org:
>
> >
> > Tor Olav Kristensen <tor_olav_kCURLYAhotmail.com> wrote in message
> >>
> >> So here is a little quiz: Can anyone guess how this was done ?
> >
> > no idea really. it migh tbe interesting, but if it takes longer
> > without a light source and the images are *almost* identical, what's
> > the point? unless the non light_source image produces nice shadows,
> > which isn't evident here.
>
> Actually, this "method" does not produce shadows at all.
> (It therefore provides a way to use a shadowless light source
> to make phong highlights for isosurfaces.)
>
> The highlights in the texture are controlled by a function.
> (I.e.: The highlights are kind of "built into" the texture.)
>
> I made a macro that builds functions that can be used to
> control texture maps, pigment maps, color maps etc. for
> isosurface shapes.
>
> One just have to tell the macro about the camera position,
> the position of the "virtual" light source and the amount
> of ambient, diffuse and specular (phong) reflection for the
> surface. One can also tell the macro about how the light
> is attenuated as it "moves" away from the light source.
> (Of coarse, the macro also needs to know the function for
> the isosurface shape itself.)
>
> You can find attached 2 more images that were made with
> this macro. The "virtual" light source has the same
> position in space as in the other images. But the textures
> in the texture_map are different.
>
> I'm not sure yet if all this is useable for more than
> generating special effects.
>
>

well that all is interesting. So are these pictures. what you do continues
to amaze me, i completely love all your isosurface posts. now that i kind of
understand what you are doing here, these picture are really cool.


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From: Tor Olav Kristensen
Subject: Re: With and without a light_source - 2 attachments - 2 attachments
Date: 24 Jun 2003 22:34:42
Message: <Xns93A57435F6CCtorolavkhotmailcom@204.213.191.226>
"Ross Litscher" <lit### [at] osuedu> wrote in
news:3ef8cdce@news.povray.org: 

... 
> well that all is interesting. So are these pictures. what you do
> continues to amaze me, i completely love all your isosurface posts.
> now that i kind of understand what you are doing here, these picture
> are really cool. 

Thank you Ross for these encouraging words !


Tor Olav


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