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 wrote:
> 
>   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/
> 

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.

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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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?

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

Post a reply to this message

Warp wrote:
> 
>   Should I mention this? If yes, could you write a more specific description
> of the phenomenon?
> 

I don't think it's neccessary, because it is a very rare case.  

I have never used megapov's motion blur, but maybe it's even possible to
simulate this specific effect, because as said in the docu motion_blur also
works on light sources.  If you change the light brightness using clock and
apply motion blur it could give the intended effect. (i did not check if it
works) 

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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it's simple.  i used it in the dark once against a black background to
do the james bond opening (walk on camera and shoot the camera).  the
flash went off ten times during the 4 second exposure, so there were ten
of me on film.  if i had done it with the lights on, the ten of me would
have been part of a continuous blur but would have been sharper than the
blur.  make sense?

Christoph Hormann wrote:
> 
> Warp wrote:
> >
> >   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/
> >
> 
> 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.
> 
> Christoph
> 
> --
> Christoph Hormann <chr### [at] gmxde>
> Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Warp wrote:

>  If you have some good topic suggestion for this section, please let me
>know.

Maybe, "I've put a sun in a corner of my picture, it's oval, not round" 
and other effect of perspective that are thought of as distortions.


Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/

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Christoph Hormann 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,........

In sports photography it's used rather often. It suggegst action and add 
drama to the picture.

Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/

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What about the misconception that POV-Ray's objects are solid when they are
all really surfaces?
Brendan

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Warp wrote:

>   The topic says it.
>   If you have some good topic suggestion for this section, please let me
> know.

Povray is not a modeller.

Post a reply to this message

Brendan wrote:

> What about the misconception that POV-Ray's objects are solid when they are
> all really surfaces?

They *are* solid, but the texturing is superficial.

--
David Fontaine   <dav### [at] faricynet>   ICQ 55354965
Please visit my website:  http://davidf.faricy.net/

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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.
|
|   And the URL was: http://iki.fi/warp/povVFAQ/

I'll try that again.  Somehow my previous reply lost first use of the word
"moon":

Difficult thing to discern from other things already in the VFAQ.
A misconception could mean beliefs other than POV-specific features.
Such as, is a moon lit on the unseen side?  But then becomes POV-related
when you're wondering if light from a sun object is behind the moon will
illuminate objects behind it via reflected light.  That's already one, sort
of.
Anyway, not easy to think of something.  And I can't think of any very
frequently asked misconceptions at the moment.

Bob

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David Fontaine <dav### [at] faricynet> wrote:
: They *are* solid, but the texturing is superficial.

  Nope. They are only surfaces.
  They are solid when interacting with fog and media, but that's all.

  A simple test: Move the camera inside an object. Is it solid?

  Btw, media is one exception where an "object" is not a surface, but more
or less solid. However, media is seldom considered an object.

-- 
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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Yes, as someone already noted: Although the misconceptions don't have to
be directly related to povray, it would be good if there was even some
connection and the topic is sometimes seen in povray groups.

  For example, thinking that the positive magnetic pole of the Earth is near
the geographic north pole is a misconception (the positive magnetic pole is
actually near the geographic south pole of the Earth). However, it could
hardly qualify as a logical entry 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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- povray is slow
- a sphere must always look like a circle (same as Ingo)
- water is blue (check last IRTC !!)
- grass is green (rgb <0,1,0>) ...
- a candle flame doesn't cast shadows (when another source is there)

Fabien.

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ingo <ing### [at] homenl> wrote:
: Maybe, "I've put a sun in a corner of my picture, it's oval, not round" 
: and other effect of perspective that are thought of as distortions.

  I added an entry about this.

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

Post a reply to this message

Greg M. Johnson <gre### [at] my-dejanewscom> wrote:
: Povray is not a modeller.

  What exactly is the misconception and what should be made clear?

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

Post a reply to this message

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 ;-)


*** Nicolas Calimet
*** http://pov4grasp.free.fr

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> 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.

	I don't agree that the light source *must* be close to the camera.
Simply this is the most common situation when the internal or added flash
of the camera is used to do this effect.


*** Nicolas Calimet
*** http://pov4grasp.free.fr

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Could you write some hints as what to respond to these (except the
sphere one)?

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

Post a reply to this message

Warp wrote:

>   Nope. They are only surfaces.
>   They are solid when interacting with fog and media, but that's all.
>
>   A simple test: Move the camera inside an object. Is it solid?

Objects are solid clear acrylic with an ior of 1.0
teehee

--
David Fontaine   <dav### [at] faricynet>   ICQ 55354965
Please visit my website:  http://davidf.faricy.net/

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:39b27854@news.povray.org...
>   For example, thinking that the positive magnetic pole of the Earth is
near
> the geographic north pole is a misconception (the positive magnetic pole
is
> actually near the geographic south pole of the Earth). However, it could
> hardly qualify as a logical entry in the VFAQ :)


That depends on whether you were, just then, working out an animation on the
subject. :)

Grim

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:39b28c22@news.povray.org...
>   Could you write some hints as what to respond to these (except the
> sphere one)?
>
> --

The last one draws my attention.

Grim

Post a reply to this message

GrimDude <vos### [at] yahoocom> wrote:
: The last one draws my attention.

  I think it has something to do with the ior of the air/flame.

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

Post a reply to this message

"David Fontaine" <dav### [at] faricynet> wrote in message
news:39B2D06E.D2D88E96@faricy.net...
| Warp wrote:
|
| >   Nope. They are only surfaces.
| >   They are solid when interacting with fog and media, but that's all.
| >
| >   A simple test: Move the camera inside an object. Is it solid?
|
| Objects are solid clear acrylic with an ior of 1.0

But if not clear and you don't take a light with you it'll appear to be
solid.  In fact, even if semi-transparent you would see everything as the
pigment of the object around you; unless there is a pattern to suggest
otherwise.

Bob

Post a reply to this message

Bob Hughes <per### [at] aolcom?subject=pov-news:> wrote:
: In fact, even if semi-transparent you would see everything as the
: pigment of the object around you

  Nope, because if it's semi-transparent light will go through the surface
and shade the interior.

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

Post a reply to this message

On Mon, 4 Sep 2000 02:37:01 -0500, GrimDude wrote:
>"Warp" <war### [at] tagpovrayorg> wrote in message
>news:39b28c22@news.povray.org...
>>   Could you write some hints as what to respond to these (except the
>> sphere one)?
>>
>> --
>
>The last one draws my attention.

Are you a moth?

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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Misconception: With povray 3.1g, you can make your own spotlight form
scratch. All you need is a light source located at the focus of a parabolic
mirror.

When I first got CorelDream3D, and perhaps also later with pov, I cursed the
coders that I couldn't get this to work. With CD3D, I spent probably a dozen
hours trying to get this to work.  The problem, of course, is that I didn't
understand the basest concept of how a raytracer worked: I insisted that
reflective surfaces should reflect lights!   This will work to some degree,
perhaps, with photons in  MegaPov. But the new user might not understand this
concept.

Didn't think I saw this in your list....................

Warp wrote:

>   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 -*/

Post a reply to this message

After I discarded my spotlight project in CD3D, I proceeded to try to make
caustics shine on the backs of dolphins in an underwater scene.  I of course
chose the most logical method:  putting an undulating surface which was
transparent but highly refractive between my light source and dolphins..........

Post a reply to this message

"Warp" wrote:
> If you have some good topic suggestion for this section,
> please let me know.

"What is the difference between a glow and a lens flare?"

Rune
--
\ Include files, tutorials, 3D images, raytracing jokes,
/ The POV Desktop Theme, and The POV-Ray Logo Contest can
\ all be found at http://rsj.mobilixnet.dk (updated July 23)
/ Also visit http://www.povrayusers.org

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I made an entry about this. Not about spotlights, but reflecting and
refracting light in general.

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

Post a reply to this message

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 -*/

Post a reply to this message

"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?

Post a reply to this message

"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
--
\ Include files, tutorials, 3D images, raytracing jokes,
/ The POV Desktop Theme, and The POV-Ray Logo Contest can
\ all be found at http://rsj.mobilixnet.dk (updated July 23)
/ Also visit http://www.povrayusers.org

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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 -*/

Post a reply to this message

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

-- 
François DISPOT  --  http://www.wozzeck.net
      __  __ __  __  _
|  | /  \  /  / |_  /  |/
\/\/ \__/ /_ /_ |__ \_ |\

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