I have posed an image of my first attempt at photon usage in the
povray.binaries.images group. Take a look. It's pretty ugly. I thought I'd
give it a try since the image is full of reflective and refractive
surfaces, and seems to be just begging for photons to be enabled. I know
there's a lot of settings I can play with, but I'd appreciate some pointers
if someone more experienced is willing. Here is how I currently have it
implemented:

In global_settings:

    photons {
        count 1000000
        autostop 0
        load_file "block.pho"
    }

In my area_light:

  photons {
      refraction on
      reflection on
      area_light
  }


In each clear plastic structure:

    photons {
        target
        refraction on
        reflection on
        collect off
    }

In each mirror/metal structure:

    photons {
        target
        reflection on
        collect off
    }

And that's pretty much it. Pretty basic stuff. All the other surfaces/lights
do not have a photons block in them at this time. I figured I'd start out
simple and then try to tweak from there. I was so shocked at the disgusting
results, though, that I decided to ask for recommendations before
proceeding. I must be doing something horribly wrong. :-) Thanks for your
time.

 - dan B hentschel

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I'm pretty sure it's the "area_light" part of your light_source settings. 
Get rid of that, and it should look pretty good.  I guess this isn't a bug, 
because it's in the documentation.  I'm not aware of any way around it, 
other than getting rid of "area_light".

You can still use an area_light in your light_source block, but it seems to 
work better if you leave it out of the photon block.

-- 
Jeremy
www.beantoad.com


"dan B hentschel" <dan### [at] alumritedu> wrote in message 
news:web.4158123d5dc55178a3fcf12a0@news.povray.org...
>I have posed an image of my first attempt at photon usage in the
> povray.binaries.images group. Take a look. It's pretty ugly. I thought I'd
> give it a try since the image is full of reflective and refractive
> surfaces, and seems to be just begging for photons to be enabled. I know
> there's a lot of settings I can play with, but I'd appreciate some 
> pointers
> if someone more experienced is willing. Here is how I currently have it
> implemented:
>
> In global_settings:
>
>    photons {
>        count 1000000
>        autostop 0
>        load_file "block.pho"
>    }
>
> In my area_light:
>
>  photons {
>      refraction on
>      reflection on
>      area_light
>  }
>
>
> In each clear plastic structure:
>
>    photons {
>        target
>        refraction on
>        reflection on
>        collect off
>    }
>
> In each mirror/metal structure:
>
>    photons {
>        target
>        reflection on
>        collect off
>    }
>
> And that's pretty much it. Pretty basic stuff. All the other 
> surfaces/lights
> do not have a photons block in them at this time. I figured I'd start out
> simple and then try to tweak from there. I was so shocked at the 
> disgusting
> results, though, that I decided to ask for recommendations before
> proceeding. I must be doing something horribly wrong. :-) Thanks for your
> time.
>
> - dan B hentschel
>
>

Post a reply to this message

> I'm pretty sure it's the "area_light" part of your light_source settings.
> Get rid of that, and it should look pretty good.  I guess this isn't a
bug,
> because it's in the documentation.  I'm not aware of any way around it,
> other than getting rid of "area_light".
>
> You can still use an area_light in your light_source block, but it seems
to
> work better if you leave it out of the photon block.

In addition to that, 1.000.000 photons for an area-light is an extremely
small amount. I much prefer to use spacing instead of count, and just reduce
the spacing until I get the desired quality.

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>

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"Tim Nikias" <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
> > I'm pretty sure it's the "area_light" part of your light_source settings.
> > Get rid of that, and it should look pretty good.  I guess this isn't a
> bug,
> > because it's in the documentation.  I'm not aware of any way around it,
> > other than getting rid of "area_light".
> >
> > You can still use an area_light in your light_source block, but it seems
> to
> > work better if you leave it out of the photon block.
>
> In addition to that, 1.000.000 photons for an area-light is an extremely
> small amount. I much prefer to use spacing instead of count, and just reduce
> the spacing until I get the desired quality.
>
> --
> "Tim Nikias v2.0"
> Homepage: <http://www.nolights.de>

So to clarify, should I take out the "area_light" AND increase the number of
photons? Or should I increase the number of photons if I decide to leave
the "area_light" specification in the photon {} block? I did a very small,
quick render with the area_light removed, but nothing else changed, and it
looks a lot better. I am currently in the middle of a higher-quality render
so I can really get a good look at the effect. It should be done sometime
tomorrow, I hope, and then I can evaluate what else needs to be done.
Thanks for the suggestions.

 - dan B hentschel

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"dan B hentschel" <dan### [at] alumritedu> wrote in message 
news:web.41597419aab70630a3fcf12a0@news.povray.org...
> "Tim Nikias" <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
>> > I'm pretty sure it's the "area_light" part of your light_source 
>> > settings.
>> > Get rid of that, and it should look pretty good.  I guess this isn't a
>> bug,
>> > because it's in the documentation.  I'm not aware of any way around it,
>> > other than getting rid of "area_light".
>> >
>> > You can still use an area_light in your light_source block, but it 
>> > seems
>> to
>> > work better if you leave it out of the photon block.
>>
>> In addition to that, 1.000.000 photons for an area-light is an extremely
>> small amount. I much prefer to use spacing instead of count, and just 
>> reduce
>> the spacing until I get the desired quality.

> So to clarify, should I take out the "area_light" AND increase the number 
> of
> photons?

That should produce pretty good results in many cases.

> Or should I increase the number of photons if I decide to leave
> the "area_light" specification in the photon {} block?

That should produce really good results, in combination with spacing.

IMHO, like many things, it generally depends on the focus (meaning "the main 
attraction") of your image.  If it's to show off nifty glass 
reflection/refraction with photons, then go all out.  But I'm still 
relatively new to photons as well, but I just did a couple experiments with 
lots of photons and area_lights (in the photon block too) with very small 
spacing, and it seemed to get rid of the strange artifacts.  I'm not sure 
what's "normal" in these situations, but I seemed to get pretty good results 
with       spacing 0.0002
      count 10000000
That might be a good starting point, or reduce those numbers by a factor of 
10 or 100, or increase them.  But again, that may be specific to my 
situation.

Your best bet is to take a very small subset of your image and do a few 
experiments to see what looks good.  Yep, it's pretty time consuming, but in 
the end, you'll learn a lot.  :-)  (Yeah, I hate those types of answers 
too... ;-)  )

-- 
Jeremy
www.beantoad.com

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SNIP
> with       spacing 0.0002
>       count 10000000
SNIP

Eh, isn't that combination kinda pointless? AFAIK, you use either "spacing"
and POV-Ray figures the amount of photons based on distance to lightsource
or something like that, if you use "count", you're telling POV-Ray to use a
specific amount, which it will divide amongst the lightsources... Their
mutual. Though I might have the technical details wrong, that's the main
point of using spacing vs count.

Ah, just found it: "3.6.3.2.1  Photon Global Settings" in 3.6.1 Docs, read
past the blue values and you'll find: "The number of photons generated can
be set using either the spacing or count keywords: [...]"

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>

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Thanks to all for your help. I have posted a new iteration in
povray.binaries.images.

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"Tim Nikias" <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote in 
message news:415a6379@news.povray.org...
> SNIP
>> with       spacing 0.0002
>>       count 10000000
> SNIP
>
> Eh, isn't that combination kinda pointless? AFAIK, you use either 
> "spacing"
> and POV-Ray figures the amount of photons based on distance to lightsource
> or something like that, if you use "count", you're telling POV-Ray to use 
> a
> specific amount, which it will divide amongst the lightsources... Their
> mutual. Though I might have the technical details wrong, that's the main
> point of using spacing vs count.
>
> Ah, just found it: "3.6.3.2.1  Photon Global Settings" in 3.6.1 Docs, read
> past the blue values and you'll find: "The number of photons generated can
> be set using either the spacing or count keywords: [...]"
>


Oops.  :-[

Well, I must have grabbed that code from someone.  I'm going to go find 
someone else to blame for my problems...  (just kidding)  But seriously, I 
think I did find those settings somewhere else from someone who used photons 
to do something pretty nifty.  I guess I'll have to experiment more on my 
own.

But thanks for letting me know!  :-)

-- 
Jeremy
www.beantoad.com

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> But thanks for letting me know!  :-)

NP, we're all a bunch of happy kids in here most of the time. ;-)

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>

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