What would cause light sources, located on the opposite side of opaque wall,
to illuminate the near side, as if they are shining through the wall?

I've been getting this since I switched to the beta version of POV, and put
in photons to my project.

One of the light sources.

//Leftmost LED
light_source { <0,0,0> color Red * LED_Brite
                photons { refraction on reflection on area_light }
                spotlight point_at <0,1,0> tightness 10 radius 0.1 falloff
20
                looks_like {Red_LED}     //Otherwise, they aren't visible
                translate<-2.6,0.2,-0.70>  //F-B U-D R-L Put the LEDs under
their pipes
                }

Plastic wall

#include "slp_may10\top_housing.inc"
object {TOP_HOUSING
        photons{target reflection on refraction off collect on}
        }

The view point is above the plastic looking down, the leds are below,
looking up.
I posted a section of the image in povray.binaries.images that shows the
problem.

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In article <3d2887b7$1@news.povray.org>,
 "Dave VanHorn" <dva### [at] cedarnet> wrote:

> What would cause light sources, located on the opposite side of opaque wall,
> to illuminate the near side, as if they are shining through the wall?
> 
> I've been getting this since I switched to the beta version of POV, and put
> in photons to my project.

How thick is this wall? If it is just a shape surface, it is infinitely 
thin, and POV might not be able to decide which side of the surface the 
photons belong to. If you give the wall some actual thickness, this 
might go away.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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> How thick is this wall? If it is just a shape surface, it is infinitely
> thin, and POV might not be able to decide which side of the surface the
> photons belong to. If you give the wall some actual thickness, this
> might go away.

It's just a surface made of triangles, translated from pro-engineer.
I don't know how I could convert it to have thickness.
I was sort of afraid this might be the case.

I've tried varying the intensity of the LEDs, it gets better with lower
intensities, but never goes away.  I guess I'll have to turn the photons off
on the LEDs, which is a pity.

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Try decreasing the 'radius' of the photons (in global_settings { photons{} })

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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> What would cause light sources, located on the opposite side of opaque
wall,
> to illuminate the near side, as if they are shining through the wall?
>
> I've been getting this since I switched to the beta version of POV, and
put
> in photons to my project.
>
> One of the light sources.
>
> //Leftmost LED
> light_source { <0,0,0> color Red * LED_Brite
>                 photons { refraction on reflection on area_light }
>                 spotlight point_at <0,1,0> tightness 10 radius 0.1 falloff
> 20
>                 looks_like {Red_LED}     //Otherwise, they aren't visible
>                 translate<-2.6,0.2,-0.70>  //F-B U-D R-L Put the LEDs
under
> their pipes
>                 }
>
> Plastic wall
>
> #include "slp_may10\top_housing.inc"
> object {TOP_HOUSING
>         photons{target reflection on refraction off collect on}
>         }
>
> The view point is above the plastic looking down, the leds are below,
> looking up.
> I posted a section of the image in povray.binaries.images that shows the
> problem.

if you don't need the photons to interact with the (whatever you call it),
you can add
photons{collect off}
to the object and it will ignore the photons.

-tgq

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:3d28c903@news.povray.org...
>   Try decreasing the 'radius' of the photons (in global_settings {
photons{} })

Turning off photons on the LEDs solved it for me, but I've hit another
issue.

I get warning messages like
       "Cannot use pass through with refraction and high density photons".

Not sure how I got to "high density" photons..  I do want refraction and
photons though.

Also, as part of getting through this, I added a "split_union off" to the
final object, which is a union of the printer, table, and a pen. Now I get a
warning that the camera is inside a non-hollow object.

Could it be that I'm inside a bounding box?

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"Dave VanHorn" <dva### [at] cedarnet> wrote...
>
> I get warning messages like
>        "Cannot use pass through with refraction and high density photons".
>
> Not sure how I got to "high density" photons..  I do want refraction and
> photons though.

That should say "cannot use pass through with refraction on a target."  So,
you have to either remove refraction, pass_through, or target.

-Nathan

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"Nathan Kopp" <nat### [at] koppcom> wrote in message
news:3d2a2250$1@news.povray.org...
>
> "Dave VanHorn" <dva### [at] cedarnet> wrote...
> >
> > I get warning messages like
> >        "Cannot use pass through with refraction and high density
photons".
> >
> > Not sure how I got to "high density" photons..  I do want refraction and
> > photons though.
>
> That should say "cannot use pass through with refraction on a target."
So,
> you have to either remove refraction, pass_through, or target.

Well that certainly makes more sense.
Now I have to figure out to what it's referring.

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