I've been experimenting with photons in this beach scene and I'm not 100% 
sure if my setup is correct. This is the setup that I'm working with. Any 
comments concerning photons would be appreciated.

global_settings {
  max_trace_level 100
  number_of_waves 40

  #if (DoPhotons)
  photons {
    count 200000
    autostop 0.5
    jitter .4
    media 200, 2
    }
  #end

  }

These are light source photons (lights inside my homebrew sky sphere) ....

// sun - main lighting
 light_source {
   <0,0,0>
   color PaleGoldenrod
   looks_like {
     sphere {<0,0,0>, 0.095
       material {Sun}
       hollow on
       interior {
          media {
          scattering {5, rgb 0.025}
          density {
          spotted
          scale 0.095
          color_map {
            [0.0 rgb <1.0000, 0.0000,0.4980>]
            [0.5 rgb <0.9525, 0.2695,0.0000>]
            [1.0 rgb <0.5430, 0.1445,0.0000>]
            }
          warp {turbulence 10}
          }
         }
       }
       //finish {ambient 3}
       translate <0,-0.125,0>
       }
     }

   #if (DoPhotons)
   photons {
    refraction on
    reflection on
    }
   #end

   translate <0,0,2.5>
   rotate <357,230,0>
   media_interaction on
   media_attenuation on
   fade_distance 7.2*WorldSize
   fade_power 0.5
   }

 // additional lighting
 light_source {
  <0,2,0>
  color PaleGoldenrod
  area_light
  <1, 0, 1> <-1, 0, -1> 3, 3
  adaptive 2
  jitter
  circular
  orient
  media_interaction off
  media_attenuation off
  fade_distance WorldSize*1.25
  fade_power 1

  #if (DoPhotons)
  photons {
    reflection on
    refraction on
    }
  #end

  }

and finally the targets .....

// the water
  #if (Detail)
    disc {
     <0,0.0001,0>, <0,1,0>, 2.75*WorldSize
     hollow on
     material {Water}

     #if (DoPhotons)
     photons {
       target
       reflection on
       refraction on
       collect on
       }
     #end

     }
  #end

#declare CatTail =
union {
  object {
    Reeds
    rotate <0,-10,0>
    }
  object {
    Stem
    translate <0.01,0,-0.01>
    scale 0.95
    }
  object {Tail}

  #if (DoPhotons)
     photons {
       target
       reflection on
       refraction on
       collect on
       }
     #end

  };

After rendering at :   +am2 +a0.1 +r6 +fn
I spotted this in the messages pane:

Number of photons shot:           93273
Surface photons stored:               1
Priority queue insert:         60761272
Gather function called:        62614147

Does that mean that I only got  1  valid photon?

Thanks Jim

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Attachments:
Download 'Beach.png' (488 KB)

Preview of image 'Beach.png'

Jim Holsenback wrote:
> 
> Number of photons shot:           93273
> Surface photons stored:               1
> Priority queue insert:         60761272
> Gather function called:        62614147
> 
> Does that mean that I only got  1  valid photon?

Yes, in such a scene you will never get reasonable results with photons 
when you shoot them at the whole water surface.

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.tu-bs.de/~y0013390/ (Last updated 24 Jul. 2005)
MegaPOV with mechanics simulation: http://megapov.inetart.net/

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"Christoph Hormann" <chr### [at] gmxde> wrote in message 
news:dea2o0$6vg$1@chho.imagico.de...
> Jim Holsenback wrote:
>>
>> Number of photons shot:           93273
>> Surface photons stored:               1
>> Priority queue insert:         60761272
>> Gather function called:        62614147
>>
>> Does that mean that I only got  1  valid photon?
>
> Yes, in such a scene you will never get reasonable results with photons 
> when you shoot them at the whole water surface.

    Yikes .... I thought so! Is there anyway to only look at a section of my 
water plane?
    I wanted to try to get some sparkles on the water. Am I on a fools 
errand?

Jim
>
> Christoph
>
> -- 
> POV-Ray tutorials, include files, Landscape of the week:
> http://www.tu-bs.de/~y0013390/ (Last updated 24 Jul. 2005)
> MegaPOV with mechanics simulation: http://megapov.inetart.net/

Post a reply to this message

Jim Holsenback wrote:
> 
>     Yikes .... I thought so! Is there anyway to only look at a section of my 
> water plane?

To only get photons shot at a part of your water only activate them for 
a part of the water. ;-)

>     I wanted to try to get some sparkles on the water. Am I on a fools 
> errand?

Photons won't show up on the water but you might get them on the ground 
below the water or on surfaces above the water.

It is unlikely though that this would have a significant effect in such 
a scene (caustics are not a very common effect in real life sunset 
scenes either).

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.tu-bs.de/~y0013390/ (Last updated 24 Jul. 2005)
MegaPOV with mechanics simulation: http://megapov.inetart.net/

Post a reply to this message

"Christoph Hormann" <chr### [at] gmxde> wrote in message 
news:dea7v1$869$1@chho.imagico.de...

> To only get photons shot at a part of your water only activate them for a 
> part of the water. ;-)

would that be the radius keyword?

radius <gather_radius>,<multiplier>,
          <gather_radius_media>,<multiplier>

or better yet what would YOU do to get sparkles on the water .... should I 
be reworking my Water material?

Thanks

Post a reply to this message

> > To only get photons shot at a part of your water only activate them for
a
> > part of the water. ;-)
>
> would that be the radius keyword?


I believe you have to make two separate water objects, one infinite (so it
goes out to the horizon) and one smaller (so it's only near your scene). You
could use the top of a big, short cylinder for the smaller part, and just
translate it slightly vertically so that it pops up above the infinite water
plane. Then shoot photons at the cylinder.

> or better yet what would YOU do to get sparkles on the water .... should I
> be reworking my Water material?

Well, photons aren't the right solution here. Photons won't change the
appearance of the water; rather, they'll bounce off the water and illuminate
whatever else they hit.

Since in real life, sparkles are caused by light reflecting off the water
into our eyes, specular highlights (phong or specular in the finish) may be
the best way to achieve this, but you might have to change the water's
normal to make the highlights the right size. (If so, you might try the
wrinkles pattern to get both large and small variations in the water
surface.) If you don't already have one there, put a red light source way
off in the direction of the sun. Then add a high specular value to the water
(higher = brighter sparkles) like 1 or 2, and a low roughness value (lower =
smaller sparkles) like .01 or less.

If you can't get the effect you want this way, you might try Chris Colefax's
"Lens Flare" include file which has a water-sparkle example.

 - Slime
 [ http://www.slimeland.com/ ]

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Jim Holsenback wrote:
> "Christoph Hormann" <chr### [at] gmxde> wrote in message 
> news:dea7v1$869$1@chho.imagico.de...
> 
> 
>>To only get photons shot at a part of your water only activate them for a 
>>part of the water. ;-)
> 
> 
> would that be the radius keyword?
> 
> radius <gather_radius>,<multiplier>,
>           <gather_radius_media>,<multiplier>
> 
> or better yet what would YOU do to get sparkles on the water .... should I 
> be reworking my Water material?

To get sparkles on the water you could use
specular or phong in the finish statement
of your water texture. This doesn't even
require photons.

Sebastian

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"Sebastian H." <van### [at] gmxde> wrote in message 
news:4308b928$1@news.povray.org...

> To get sparkles on the water you could use
> specular or phong in the finish statement
> of your water texture. This doesn't even
> require photons.
>
> Sebastian

ahhh ... as the previous response also mentioned .... back to the drawing 
board on the Water material.

Thanks Much

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High!

I'm in doubt whether clouds can be already that reddened with the sun 
still halfway above the horizon - I've in fact seen such evening skies, 
but then the sun already has set completely, i. e. was not seen anymore...

See you in Khyberspace!

Yadgar

Now playing: Silver Circle (Bakmak)

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news:430aae26$1@news.povray.org...
> High!
>
> I'm in doubt whether clouds can be already that reddened with the sun 
> still halfway above the horizon - I've in fact seen such evening skies, 
> but then the sun already has set completely, i. e. was not seen anymore...

Hmmmm .... you could be right but it seems to me that I've seen sunsets 
simular to the one attempting to model.
But what the hey it's POV I'm allowed a little poetic license aren't I?

Ciao

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