"Zeger Knaepen" <zeg### [at] povplacecom> wrote in message 
news:47b29ef9$1@news.povray.org...
>
> it's called chromatic dispersion in POV-Ray: 
> http://www.povray.org/documentation/view/3.6.1/415/


Glad to see you guys answering this time of night-- well, almost 2 a.m. 
local time for me-- maybe you're someplace with daylight...? LOL

That last paragraph of 2.6.1.5 Dispersion, before the section about 
'caustics', will tell you this isn't about light being spread into actual 
wavelengths. You use 'photons' to get the light transported onto other 
surfaces or through air, otherwise this is only internal to transparent 
objects that are also refractive (ior 1 for the refraction is ok).

One of my favorite things about POV-Ray, such light characteristics. Great 
that it was thought of before the talk ended completely.

Bob

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"Mike Williams" <nos### [at] econymdemoncouk> wrote in message 
news:3KI### [at] econymdemoncouk...
>
> I vaguely seem to remember that the documentation for DKBTrace claimed 
> that chromatic aberration was "a bug in the real world" and was therefore 
> not then supported.


Wow, that's thinking back a few years before I first used POV-Ray. :^D

Trying to remember if a mirror, or any opaque reflective object, can also do 
this when the light shines onto something next to it (ior added, of course). 
I haven't been doing much with POV past couple years far as creative renders 
go. I'd probably know for certain if I had been doing more things with it.

Bob

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Mike Williams wrote:
> Wasn't it William Tracy who wrote:
> I vaguely seem to remember that the documentation for DKBTrace claimed 
> that chromatic aberration was "a bug in the real world" and was 
> therefore not then supported.
> 

That's a cute comment but I don't recall saying it in the documentation 
and a quick scan of the documentation for DKBTrace seems to show no 
trace of it.

David Buck

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>>>>> "Bob" == Bob Hughes <omn### [at] charternet> writes:

Bob> One of my favorite things about POV-Ray, such light characteristics. Great
Bob> that it was thought of before the talk ended completely.

So Leo was right!  Cool.  I kept thinking "That's hard to program so
it probably doesn't do it".  :)  Darn programmer in me.

-- 
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<mer### [at] stonehengecom> <URL:http://www.stonehenge.com/merlyn/>
Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl training!

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Randal L. Schwartz wrote:
>>>>>> "Bob" == Bob Hughes <omn### [at] charternet> writes:
> 
> Bob> One of my favorite things about POV-Ray, such light characteristics. Great
> Bob> that it was thought of before the talk ended completely.
> 
> So Leo was right!  Cool.  I kept thinking "That's hard to program so
> it probably doesn't do it".  :)  Darn programmer in me.
> 

It wasn't in DKBTrace and early versions of POVRay.  Since raytracing 
traces light rays backwards from the eye towards the world, when the 
light goes through a prism, you'd have to split one ray into lots of 
other rays with different colors.  This seems to be what the POVRay 
dispersion feature does.

The other complication (which POVRay tries to fake) is that the rays in 
a raytracer only track three colors - red, green and blue.  In the real 
world, light is (generally) a blend of lots of different wavelengths. 
To get truly accurate results, we should model the light as a bundle of 
wavelengths.  Each surface will reflect some wavelengths, absorb others, 
and scatter others.  When we calculate the final wavelength bundle for a 
pixel, we can then map it onto RGB.  POVRay cheats by only assuming that 
the light only contains 3 wavelengths.

David Buck

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Randal L. Schwartz wrote:
> So Leo was right!  Cool.  I kept thinking "That's hard to program so
> it probably doesn't do it".  :)  Darn programmer in me.

I find it interesting that Povray does all sorts of conceptually 
difficult things (dispersion, volumetric media) but doesn't do many 
conceptually simple things (luminous bloom comes to mind).

(Actually, my impression is that there are some architectural 
difficulties involved with adding luminous bloom, but Warp and others 
hope to resolve that in Povray 4.)

-- 
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

    "'The Force'?"
    "The Force is an energy field--"
    "Energy? But energy is force times distance."
    "And 'power of the force' would be distance times the derivative 
with respect to time."
     -- Darths and Droids

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William Tracy <wtr### [at] calpolyedu> wrote:
> (Actually, my impression is that there are some architectural
> difficulties involved with adding luminous bloom, but Warp and others
> hope to resolve that in Povray 4.)

"luminous bloom" and glare are caustics happening inside the eye and other
camera obscura devices.  Unless povray simulates what happens inside, it won't
happen and is probably better left as a postprocess effect.

But there are SDL scripts for both "luminous bloom" and glare in povray.  The
former as a postprocess using povray itself and the latter using povray disc
objects...

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David Buck <dav### [at] simberoncom> wrote:
> The FLOSS Weekly episode on POV-Ray has now been posted.
>
>  http://twit.tv/floss24
>
> Enjoy.
>
> David Buck

Listening to floss-24 here. " ... programmer or artist ..." ?

We hear admission for lack of creativity or artistic talent, different words but
much the same.

I got something that can help.

I wrote about it earlier. People are mainly right or left brained people,
logical or creative. What that means is that one hemisphere of the brain is
used more than the other side.

Tuning is possible to get that other side up to speed. But I know you guys are
not interested. Or are you?

aQ

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Randal L. Schwartz wrote:
>>>>>> "Stephen" == Stephen  <mcavoysATaolDOTcom@> writes:
> 
> Stephen> I enjoyed the broadcast but what a pair of bankers the hosts are.
> 
> Stephen> What is a senior dude FFS?
> 
> Tell me what a "banker" is, and I'll tell you what a "senior dude" is.
> 

I'm a banker.  I handle the vault at our branch.

-- 
...Ben Chambers
www.pacificwebguy.com

(follow-ups set to o-t)

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"alphaQuad" <alp### [at] earthlinknet> wrote in message 
news:web.47b3474786589f5e73c5f880@news.povray.org...
> David Buck <dav### [at] simberoncom> wrote:
>> The FLOSS Weekly episode on POV-Ray has now been posted.
>>
>>  http://twit.tv/floss24
>>
>> Enjoy.
>>
>> David Buck
>
> Listening to floss-24 here. " ... programmer or artist ..." ?
>
> We hear admission for lack of creativity or artistic talent, different 
> words but
> much the same.
>
> I got something that can help.
>
> I wrote about it earlier. People are mainly right or left brained people,
> logical or creative. What that means is that one hemisphere of the brain 
> is
> used more than the other side.
>
> Tuning is possible to get that other side up to speed. But I know you guys 
> are
> not interested. Or are you?
>
> aQ
>

Using both sides is fun!  =;oD


-- 
-Nekar Xenos-

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