Rune <run### [at] inamecom> wrote:
: "What is the difference between a glow and a lens flare?"

  Is this a misconception or just a regular question?-)

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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"When I declare an object with a random number in the declaration and
generate multiple copies of the object (with object{}), all the objects are
the same as if I used a fixed value instead of the random number. Why?"

Marc-Hendrik

Warp schrieb in Nachricht <39afce77@news.povray.org>...
>  The topic says it.
>  If you have some good topic suggestion for this section, please let me
>know.
>
>  And the URL was: http://iki.fi/warp/povVFAQ/
>
>--
>main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
>):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:39afce77@news.povray.org...
>   The topic says it.
>   If you have some good topic suggestion for this section, please let me
> know.
>

How about "all objects have a point of origin and that is what they rotate
about when rotated" or something similiar?

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"Warp" wrote:
> "Rune" wrote:
> : "What is the difference between a glow and a lens flare?"
>
>   Is this a misconception or just a regular question?-)

I know the answer to the question myself, if that is what you mean...

About misconceptions/questions - well, I think most misconceptions can be
formulated as questions, and I believe many of the questions in the VFAQ are
based on misconceptions. (Why do my object transform in an odd way? Because
you have an misconception of how the transforms work)

So I think the edge between misconceptions and questions are a rather
blurred, and I don't really know why you added a misconceptions section in
the first place when all the misconceptions could be formulated as questions
anyway (Why do my #while-loop not work as expected?).

Greetings,

Rune
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Rune <run### [at] inamecom> wrote:
: So I think the edge between misconceptions and questions are a rather
: blurred, and I don't really know why you added a misconceptions section in
: the first place when all the misconceptions could be formulated as questions
: anyway

  My initial intention was to put more general misconceptions about computer
graphics in the misconceptions section and specific povray questions in the
questions section. The questions usually apply only to povray, while the
misconceptions have a more general meaning (although people can have them
when dealing with povray).
  The questions can also be pure questions (how do I put an image map on
a sphere?) which are not misconceptions.

: (Why do my #while-loop not work as expected?).

  I didn't put that in the misconceptions section because I felt it was more
a povray-specific question (only povray syntax explained).

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Tom Melly <tom### [at] tomandlucouk> wrote:
: How about "all objects have a point of origin and that is what they rotate
: about when rotated" or something similiar?

  Isn't this true? Every object has indeed this point: <0,0,0>

  I think a question covering this theme has been dealt already in the VFAQ.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:39b8ba42@news.povray.org...
> Tom Melly <tom### [at] tomandlucouk> wrote:
> : How about "all objects have a point of origin and that is what they
rotate
> : about when rotated" or something similiar?
>
>   Isn't this true? Every object has indeed this point: <0,0,0>
>

Mmm, yes. I should have phrased it better. Also, thinking about it, the
misconception affects new-users and scaling rather than rotation - e.g.

sphere{<2,2,2>, 1 scale 10} - hey, where did my sphere go?

>   I think a question covering this theme has been dealt already in the
VFAQ.
>

I'm sure you are right - might not some duplications between the VFAQ and
misconceptions be appropriate?

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In article <39b8ba42@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

>   Isn't this true? Every object has indeed this point: <0,0,0>

But that point moves around relative to the object depending on the 
transformation. It isn't a single point that stays constant in relation 
to the object.


>   I think a question covering this theme has been dealt already in the 
>   VFAQ.

Then there isn't much of a problem... :-)

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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Nicolas Calimet wrote:
> 
> Warp wrote:
> >
> > Christoph Hormann <Chr### [at] schunteretctu-bsde> wrote:
> > : Quite right about the motion blur, but when combining flash with long exposure
> > : times in photography, you can achieve an effect similar to the one you
> > : criticise.  Of course that's a rare occasion, and would require the main light
> > : source being near the camera, but i wanted to mention it.
> >
> >   Should I mention this? If yes, could you write a more specific description
> > of the phenomenon?
> 
>         If the shutter of the camera is open for a relatively long time (say
> for instance one second) and that a bright light flashes the scene for a
> short interval (i.e about 1/1000 of a second), this will "fix" the moving
> objects due to their higher brightness at that time. In photography it is
> more common to flash the scene just before closing the shutter to give a
> "fixed" object with a dimmed trace behind (for better composition) or to
> flash several times to give different snapshots of a moving object on a
> single photo (as when studying human walk). There may have others examples
> of using this effect, called "slow synchronization" from my french vocabu-
> lary ;-)

Right, and there are two ways to obtain this effect, depending on if you
fire the flash just after opening the shutter (front curtain sync), or
just before closing (rear curtain). An example can be found at:

http://www.minolta.com/camera/dynax7_img/synchro.gif

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