Hi,
  I am rendering a scene with media in a transparent box a little above the
ground.  The media is defined by a density file.  I shoot photons at the
media-contained box.  I then want photons to be collected on the ground
(because I want to later modify POVRay to have the media emit photons of
different "colours" onto the ground), so I declare for the ground "collect
on" in the photon block.  But when the ground is allowed to collect photons
the shadow of the box is seen, versus the shadow of the shape of the
density in the box.  The shadow of the shape of the density can be seen
when I turn photon collection off for the ground.

  Does anyone know how I can collect photons on the ground, but still have
the correct shadow?

Thanks in advance.

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Penners <pen### [at] hotmailcom> wrote:
>   I am rendering a scene with media in a transparent box a little above the
> ground.  The media is defined by a density file.  I shoot photons at the
> media-contained box.  I then want photons to be collected on the ground
> (because I want to later modify POVRay to have the media emit photons of
> different "colours" onto the ground), so I declare for the ground "collect
> on" in the photon block.

  I don't think there's need. AFAIK "collect on" is the default setting
for all objects.

>  But when the ground is allowed to collect photons
> the shadow of the box is seen, versus the shadow of the shape of the
> density in the box.  The shadow of the shape of the density can be seen
> when I turn photon collection off for the ground.

  Have you tried "pass_through" in the photons block of the box?

-- 
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}//  - Warp -

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Warp wrote:
>  Have you tried "pass_through" in the photons block of the box?

Right, but doesn't pass_through also make the photons ignore the media
inside the box?  So no media photons will be placed, correct?

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Penners <pen### [at] hotmailcom> wrote:
> >  Have you tried "pass_through" in the photons block of the box?

> Right, but doesn't pass_through also make the photons ignore the media
> inside the box?  So no media photons will be placed, correct?

  You didn't answer my question... :)

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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In article <web.3f67b1d0f785c673c6890ca10@news.povray.org>,
 "Penners" <pen### [at] hotmailcom> wrote:

>   Does anyone know how I can collect photons on the ground, but still have
> the correct shadow?

I don't think this is possible. POV will light the area in shadow with 
photons, but the rest will be lit directly. At the shadow border, there 
will probably always be a visible transition between photons and direct 
lighting. In theory, you could avoid this by lighting the entire scene 
with photons, but it would take a huge amount of photons. You could also 
minimize it by using more photons...again, a lot of photons.

Why are your photons interacting with a container shape anyway? Unless 
it's refracting, it won't have a very interesting shadow, just a waste 
of photons.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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