POV-Ray : Newsgroups : povray.newusers : Laser Light Source with Photons... : Re: Laser Light Source with Photons... Server Time
1 Jul 2025 08:48:02 EDT (-0400)
  Re: Laser Light Source with Photons...  
From: Alain
Date: 18 Jul 2008 14:24:52
Message: <4880dff4$1@news.povray.org>
Jim Holsenback nous illumina en ce 2008-07-18 10:28 -->
> "Reactor" <rea### [at] hotmailcom> wrote in message 
> news:web.487f9f80f15fb2b6210497120@news.povray.org...
>> Povray can do this, but I would like to see your code so we can figure out 
>> why
>> it isn't.
>>
>> -Reactor
> 
> Ok ..... here's the source file photons commented out. Don't need that just 
> yet right?
No! You absolutely NEED to turn photons on now. Without photons on, there is no 
reflection of the beam.
> 
> I've attached a reference image. Notice I can see the target in the 
Please don't post image here, it's not a binaries group.
Instead, include a reference to a similarly named post on povray.binaries.images

> reflective object .... also the reflection of the beam from the source. 
> That's not the beam bending but it's reflection. I also commented out the 
> optical device as I don't need that yet either. One change I made was the 
You effectifely don't need any visible object emiting your light.
> intensity of the looks_like light source ..... it WAS a color vector * 1000 
> ..... I just bumped up the intensity of the scattering media to make up for 
> lowering the intensity of the emitter light source. Orginally the light beam 
> hitting the target produced an almost white-ish look (highly saturated) 
> ..... a laser beam should leave a red (or light source) colored point of 
> light .... correct?
A laser can be any colour, from far infrared to hard UV. IR and UV are 
invisible. A UV laser can cause the air to turn fluoressent and emit light, and 
that light can have several colours, and apears white if the beam is strong enough.
Visible laser are 100% saturated, monochromatic lights. So, just make sure that 
at least one component is set to zero.
> 
> Thanks
> Jim
> ---
> 
> global_settings {
>   max_trace_level 10
>   /*photons {
>     count 100000
>     autostop 0
>     media 1000
>     max_trace_level 10
>     }*/
>   }
Uncomment that photons block. Otherwise, the beam will never get reflected.
> 
> background {rgb 0.125}
> 
> #declare Camera =  <15,1.5,2.5>;
> 
> camera { location Camera look_at <0,0,2.5>}
> 
> // makes the lightsource visable
> box {<100,100,100>,<-100,0,-100>
>   hollow on
>   pigment {rgbt 1}
>   //photons {pass_through}
>   interior {
>     media {
>       intervals 1
>       samples 1 //5,25
Need more samples. Use 100 or possibly more.
>       confidence 1 - 1/1000
>       variance 1/1000
>       ratio 0.9
>       scattering {
>         1, color rgb 10
>         extinction 0.0
>         }
>       method 3
>       aa_threshold 0.1
>       aa_level 4
You don't need that much, aa_level 2 or 3 should be enough.
>       density {color rgb <1,1,1>}
>       }
>     }
>   }
> 
> // reflector yellow border
> union {
>   box {<-2.5,-0.1,-2.5>, <2.5,0.1,2.5>
>     pigment{rgb 1}
>     finish{ ambient 0 diffuse 0 reflection 1}
>     }
>   box {<-2.6,0,-2.6>, <2.6,0,2.6>
>     pigment{rgb <1,1,0>}
>     finish{ ambient 0.5}
>     }
>   rotate z*90
>   rotate y*315
>   //photons {target reflection on refraction on}
>   }
Uncomment this. This is required for the photons to work.
> 
> // recptor blue border
> union {
>   box {<-0.1,-1.5,2.5>, <0.1,1.5,-2.5>
>     pigment {
>       onion scale 0.5
>       color_map {
>         [0.0 rgb 1]
>         [0.35 rgb 1]
>         [0.35 rgb 0.1]
>         [1.0 rgb 0.1]
>         }
>       }
>     finish{ ambient 0.5 diffuse 0.5 reflection 0 }
>     }
>   box {<0,-1.6,2.6>, <0,1.6,-2.6> pigment {rgb <0,0,4>}}
>   rotate y*90
>   //photons {target reflection on refraction on}
Not needed.
>   translate <0,0,5>
>   }
> 
> // optic device
> /*sphere  {
>   0, 0.5
>   pigment{ color rgbt <1,1,1,.95> }
>   hollow on
>   finish{ ambient 0 diffuse 0 reflection .5  }
>   interior{  ior 1.5  }
>   //photons {target reflection on refraction on}
>   scale <0.01,1,1>
>   translate <2.5,0,0>
>   }*/
> 
> // the emitter
> light_source {
>   <0,0,0>
>   color rgb <1.0000, 0.2900,0.2000>
Make it: color rgb<10,0,0> if you want a red laser.
For a laser, at least one colour component MUST be zero.
>   cylinder
For a laser, you should also add parallel.
>   tightness 0
>   radius .025
>   falloff .025
>   point_at <-1,0,0>
>   fade_distance 500
You don't need light fading in this case as the fading of laser is negligeable 
at human scale.
>   fade_power 2
>   /*photons {
>     reflection on
>     refraction off
>     }*/
Optional. Thise are on by default for any light_source.
>   looks_like {cylinder{0,<0.1,0,0>,0.1 pigment {rgb <4,0,0>}}}
>   translate <5,0,0>
>   } 
> 
> 
> 


-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you look at a matrix transform and 
know instantly what it does.
John VanSickle


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