povray.org admin team (regarding patch group) wrote:
>> not any more (remember to get new groups)

povray.unofficial.patches

  Thanks much, sir! Very appropriate and sure to be a hit.

- Alan

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>povray.unofficial.patches
>
>  Thanks much, sir! Very appropriate and sure to be a hit.

I'll second that.

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This is correct.  Thanks for answering it, Peter.  Manually bounding can speed
things up a lot sometimes (especially when using difference & intersection).

-Nathan

Peter Popov wrote:
> 
> Hi Ken.
> 
> I think I can answer this one for you.
> 
> >8.) Are there any object types that are excluded from working with
> >   the photon patch, photon specific, properties ?
> >   Of the different object types the patch seems to provide the least
> >   functionality with are triangles and meshes, it works properly with
> >   procedural primitives, and seems to really choke on CSG constructs
> >   like a shape made out of intersecting planes. The last is one that
> >   gave me the runaway photon counter mentioned above. A box trimmed
> >   with an intersecting plane works well but if you use all planes to
> >   form a refracting object it goes nuts and no parameter will change
> >   the way it reacts. This is of course a one object, one time, situation
> >   that I have not confirmed with other constructions or construction
> >   CSG types.
> 
> Photons are shot at an object's bounding box. POV is at a loss when
> trying to automatically bound an intersection of planes (or any other
> infinites) only. When you intersect a box with a plane, POV knows for
> sure that the resulting object will be bounded by the aforementioned
> box. The solution is to manually bound your CSG of planes. It will
> speed up the render, too.
> 
> ---------
> Peter Popov
> ICQ: 15002700

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Ken wrote:
> 
> Greetings Photon Phonatics !
> 
>  good thread to attach them to. That way Nathan doesn't have to go
>  chasing around the different subject groups to find it all and it will
>  be here and ready for him when he gets back from his conference trip.

Thanks!

Thanks to everyone for helping answer these questions!

> 5.)  If I collect more photons than I shoot does this indicate that I do
>    not have my gathering radius and/or the number of steps set correctly
>    or is this an ideal situation. It seems to me that in most cases you
>    would seek to have shot more photons that the number gathered.

in the stats, "photons shot" means how many light rays were shot from the
light sources.  "photons stored" means how many photons are depostited on
surfaces in the scene.  If you turn on reflection and refraction, you could
get more photons stored than photons shot, since the each ray can
get split into two.

> 6.)  If I shoot white light through a 60 degree equilateral triangle
>    should I be getting prismatic dispersion on the output ? I know
>    Darrens patch addresses this internally but was wondering about the
>    effects of external out put with no method of assigning an internal
>    dispersion characteristic.

I have implemented dispersion, but there's no default spectrum.  If you
creat your light source like this:

light_source
  <10,10,10>
  color <1,1,1> // this will be replaced, but the parser is a hack right
                //   now, so it is still required
  color_map{    // here you define your light's spectrum
                //   this color_map acts like "average":  the first value is
                //   weight (intensity), the second is color
    [1, <.5,0,0>]
    [1, <.2,.2,0>]
    [1, <.3,.3,0>]
    [1, <0,.5,.5>]
    [1, <0,0,.5>]
  }
}

Notice, the color map entries added up to <1,1,1>.  This spectrum will
probably look bad (I made it up just now), but you get the idea.

> 7.) On the same topic as above should light bend in accordance with
>    the natural laws of physics or is the photon model used in the
>    patch more of a visual gimmick than a relativistic lighting model.
>    I have observed unnatural behaviour in three different prisms
>    constructed using differing methods. Each was tried with a wide
>    range of both photon related parameters and options as well as
>    changes in refraction, reflection, and  the filter/transmit values.
>    None of the computer based models matched a physical prism I have
>    been using as a reference for comparison.

It does follow the laws of physics.  (not relativity, though.)  Make
sure you use an IOR value that matches the real prism.

-Nathan Kopp

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Nathan Kopp wrote:

> > 6.)  If I shoot white light through a 60 degree equilateral triangle
> >    should I be getting prismatic dispersion on the output ? I know
> >    Darrens patch addresses this internally but was wondering about the
> >    effects of external out put with no method of assigning an internal
> >    dispersion characteristic.
> 
> I have implemented dispersion, but there's no default spectrum.  If you
> creat your light source like this:
> 
> light_source
>   <10,10,10>
>   color <1,1,1> // this will be replaced, but the parser is a hack right
>                 //   now, so it is still required
>   color_map{    // here you define your light's spectrum
>                 //   this color_map acts like "average":  the first value is
>                 //   weight (intensity), the second is color
>     [1, <.5,0,0>]
>     [1, <.2,.2,0>]
>     [1, <.3,.3,0>]
>     [1, <0,.5,.5>]
>     [1, <0,0,.5>]
>   }
> }
> 
> Notice, the color map entries added up to <1,1,1>.  This spectrum will
> probably look bad (I made it up just now), but you get the idea.

  Ah ! Undocumented features surfacing. Any other little easter eggs
hidden in there that you haven't mentioned ?

 
> > 7.) On the same topic as above should light bend in accordance with
> >    the natural laws of physics or is the photon model used in the
> >    patch more of a visual gimmick than a relativistic lighting model.
> >    I have observed unnatural behaviour in three different prisms
> >    constructed using differing methods. Each was tried with a wide
> >    range of both photon related parameters and options as well as
> >    changes in refraction, reflection, and  the filter/transmit values.
> >    None of the computer based models matched a physical prism I have
> >    been using as a reference for comparison.
> 
> It does follow the laws of physics.  (not relativity, though.)  Make
> sure you use an IOR value that matches the real prism.
> 
> -Nathan Kopp

 I tried everything from ior 1.0 to 4.5 and had little difference in the
refraction of the light. I will continue with my experiments and see
where then I am at fault. It may be a that the internal reflections are
not high enough or the material specification is wrong.

 On a side note did you by any chance see my questions in the new
unofficial patch directory concerning some of the other features
of your patch ?

-- 
Ken Tyler

mailto://tylereng@pacbell.net

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Am I missing something? That group doesn't show up? (forgive my ignorance.
please).

GrimDude
vos### [at] arkansasnet
Ron Parker wrote in message <36ff896c.0@news.povray.org>...
>>povray.unofficial.patches
>>
>>  Thanks much, sir! Very appropriate and sure to be a hit.
>
>I'll second that.

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GrimDude wrote:
> 
> Am I missing something? That group doesn't show up? (forgive my ignorance.
> please).

> >>povray.unofficial.patches

It's there. Just have to hit the subscribe to groups button and it should
show. Not much there yet but it has potential.

-- 
Ken Tyler

mailto://tylereng@pacbell.net

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>>   4. What's the meaning of life?
>42.
>


Hitchhiker had it wrong. :)

32! Unless you arbitrarily assign the question mark a value of 10. Heh

GrimDude
vos### [at] arkansasnet

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Thanks, Ken! Actually it was "reset list" which I consider to be a poor
label for the function, but it works. :)

GrimDude
vos### [at] arkansasnet

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