Here is a transparent blob over a plane plane.

I have one question, can anyone explain why when I set the colour of the
plane to black the photons don't show up?  What I really want is just a
black background with the caustics from the lights.  I can't seem to get
this, I have to make the plane grey (0.1) to make them show up.

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Preview of image 'blobs.jpg'

scott wrote:
> Here is a transparent blob over a plane plane.
>
> I have one question, can anyone explain why when I set the colour of
> the plane to black the photons don't show up?  What I really want is
> just a black background with the caustics from the lights.  I can't
> seem to get this, I have to make the plane grey (0.1) to make them
> show up.

Sorry, that's a dumb question isn't it!! No, I don't feel stupid now :-)

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417508d8$1@news.povray.org...
> scott wrote:
>
> Sorry, that's a dumb question isn't it!! No, I don't feel stupid now :-)
>
Who never does? ;-)
You could achieve a better contrast  by settin plane ambient to 0 if not yet

Marc

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sco### [at] spamcom news:417507e1@news.povray.org

> I have one question, can anyone explain why when I set the colour of the
> plane to black the photons don't show up? 

Because the light is not deffused, even the one from photons.

Btw, I think that adding  diffuse_photons (with by default equals to 
deffuse) would be a good idea. Such oimages would not be corect from 
phisics point of view, but this can be used to make nice artistic images.

As for now, perhaps You could use something like

plane { ...
  pigment { rgb 1 }
  finish { diffuse .5 ambient -.5 }
}

or simmilar? 
AFAIK that way direct right would have intensity of:

  light-source * material-color * material-diffuse + material-ambient
= 1 * 1 * 0.5 - 0.5 = 0

and concentrated photons caustic would be in example

10 * 1 * 0.5 - 0.5 = 9.5 = 1 (after clipping)


-- 
http://www.raf256.com/3d/
Rafal Maj 'Raf256', home page - http://www.raf256.com/me/
Computer Graphics

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Rafal 'Raf256' Maj wrote:
> sco### [at] spamcom news:417507e1@news.povray.org
>
>> I have one question, can anyone explain why when I set the colour of
>> the plane to black the photons don't show up?
>
> Because the light is not deffused, even the one from photons.

I know, I realised this just after I'd posted!

> As for now, perhaps You could use something like
>
> plane { ...
>   pigment { rgb 1 }
>   finish { diffuse .5 ambient -.5 }
> }
>

Thanks for that idea, it worked pretty well.  Except that some of the
"colour" of the blob was actually due to the colour of the plane.  Anyway,
after a bit of tweaking I came up with this, which is far closer to what I
wanted.

pigment{ color rgb <1,1,1> }
   finish {
         diffuse 0.5
         ambient -1.1
      }

Cheers!

Scott

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Preview of image 'blobs.jpg'

Would you be willing to post the source for this image?  I think I could learn a lot
from your work.

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"Spock" <Spo### [at] nospamcom> wrote in message
news:41753a82$1@news.povray.org
> Would you be willing to post the source for this image?  I think I
> could learn a lot from your work.

No probs, its in p.b.s-f now under the same subject.

Hope you can understand it, it's a bit messy!

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Scott,

This is great and really shows off photos. 
Kudos to you!

Mike

scott wrote:
> Rafal 'Raf256' Maj wrote:
>> sco### [at] spamcom news:417507e1@news.povray.org
>>
>>> I have one question, can anyone explain why when I set the colour of
>>> the plane to black the photons don't show up?
>>
>> Because the light is not deffused, even the one from photons.
> 
> I know, I realised this just after I'd posted!
> 
>> As for now, perhaps You could use something like
>>
>> plane { ...
>>   pigment { rgb 1 }
>>   finish { diffuse .5 ambient -.5 }
>> }
>>
> 
> Thanks for that idea, it worked pretty well.  Except that some of the
> "colour" of the blob was actually due to the colour of the plane.  Anyway,
> after a bit of tweaking I came up with this, which is far closer to what I
> wanted.
> 
> pigment{ color rgb <1,1,1> }
>    finish {
>          diffuse 0.5
>          ambient -1.1
>       }
> 
> Cheers!
> 
> Scott

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Hey, that's really great. :-D

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Mike Kost wrote:
> Scott,
> 
> This is great and really shows off photos.
> Kudos to you!
> 

Umm... that's photoNs...

Mike

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