"Anthony D. Baye" <Sha### [at] hotmailcom> wrote in message
news:42f0342b$1@news.povray.org...
<snip>
> so when you look at a light bulb, it's not really the light you're
> seeing, but the glowing filament, and the light bulb of course.

That's not exactly correct.  It is the light/photons/radiation that you are
seeing, not the object.

The object is only seen because photons are being reflected off it, or because
it is producing photons.  After all, our eyes can't sense objects (we use touch
for that), they can only sense light (and the polarisation of light).

:)

Lance.

thezone - thezone.firewave.com.au

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"Anthony D. Baye" <Sha### [at] hotmailcom> wrote in message
news:42efcdf9$1@news.povray.org...
> Christoph Hormann wrote:
> > Anthony D. Baye wrote:
> >
> >>
> >>     So my question is:  Is there an eficient way to model Optical
> >> fibers, so that they not only glow, but transmit the light along the
> >> length as well.
> >>     Naturally, I'll continue my own experimentations.  I would however
> >> appreciate any thoughts people might have on the subject.
> >
> >
> > The transmission of light is nothing that makes sense to simulate in
> > POV-Ray since it has no effect on the image POV-Ray renders (light
> > itself isn't visible).  Therefore using emitting media for the glow and
> > placing a spotlight at the end is the way to go.
> >
> > Christoph
> >
> Hey Christoph,
>
> Thanks for the input.  The only problem that I see with your solution
> is that, if I were trying to model one of those fiber optic displays
> (f/ex. The flowers with the FO strands in them) I would have hundreds of
> spotlights in my scene.  The light calculations would take forever.

How many strands are you trying to simulate?  If you're talking more than just a
few, the number of calculations to properly simulate the total internal
reflection of fibre optics using photons would be *astronomical*.

It doesn't mean it can't be done, but it will take so much time that I suspect
it won't be worth doing.

High quality fibre optics don't glow along the entire fibre, either - if it was
to glow along the entire fibre it means that total internal reflection isn't
being achieved, and therefore the fibre is being *very* inefficient (it's losing
most of its light out the sides of the fibre, rather than out the end).  The
light should only be escaping from the end of the fibre.

Lance.

thezone - thezone.firewave.com.au

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Anthony D. Baye nous apporta ses lumieres en ce 2005-08-02 22:46:
> Lonnie wrote:

> 
> What's a swap file?
> 
> I'm on a Mac.  maybe it's called something else.
> 
> A.D.B.
Virtual memory. A file on disk where the OS puts data when it runs short of physical
memory. It's 
called swap because you swap chunks of data and programms between it and the RAM.

Alain

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"Anthony D. Baye" <Sha### [at] hotmailcom> wrote:
> Lonnie wrote:
> > This might actually be made to work with photons, although be prepared to
> > have your swap file limit increased to an astonomical size and a LONG
> > render time!
> >
> >
>
> What's a swap file?
>
> I'm on a Mac.  maybe it's called something else.
>
> A.D.B.

A "swap file" or more correctly a page file, is what a Windows computer uses
when it runs out of RAM.  Data is "swapped" in and out of memory to the
hard disk as needed.  While it works OK for background tasks that only need
to access their data occasionally, things like a big photon map will slow a
system to a crawl.  The CPU is spending far more time waiting on the hard
disk than it is crunching numbers.  I'm not sure how a Mac does this, but
it has to be something similiar.

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In article <web.42f89fab22ec88d03b3a698d0@news.povray.org>, 
lon### [at] yahoocom says...
> "Anthony D. Baye" <Sha### [at] hotmailcom> wrote:
> > Lonnie wrote:
> > > This might actually be made to work with photons, although be prepared to
> > > have your swap file limit increased to an astonomical size and a LONG
> > > render time!
> > >
> > >
> >
> > What's a swap file?
> >
> > I'm on a Mac.  maybe it's called something else.
> >
> > A.D.B.
> 
> A "swap file" or more correctly a page file, is what a Windows computer uses
> when it runs out of RAM.  Data is "swapped" in and out of memory to the
> hard disk as needed.  While it works OK for background tasks that only need
> to access their data occasionally, things like a big photon map will slow a
> system to a crawl.  The CPU is spending far more time waiting on the hard
> disk than it is crunching numbers.  I'm not sure how a Mac does this, but
> it has to be something similiar.
> 
Probably more efficiently though. Unless they fixed it in XP, the problem 
was that it started paging once a certain percentage of memory was used 
at one shot, even if you still had a significant amount left. Something 
stupid like 1MB or something on the older versions of Windows. This is 
what made games lag. If you moved around more than X megs in one shot, 
the memory manager would start paging out, even if you still had 90% of 
your physical RAM available. Or at least that is what I read anyway, when 
someone described the problem.

-- 
void main () {

    call functional_code()
  else
    call crash_windows();
}

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