How can i take a light source and reflect the light off a mirror type
object and get both beams of light (incident and reflected) to show up
in media? I tried using photons and media.... but I cannot seem to get
the reflected light to interact with the media....

--
-------------------------------------------#
Paul Daniel Jones
307 Chandlee Laboratory
Penn State University
814-865-2090
pdj### [at] psuedu

http://research.chem.psu.edu/glassgrp/paul
--------------------------------------------#

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Paul Daniel Jones <pdj### [at] psuedu> wrote:

> How can i take a light source and reflect the light off a mirror type
> object and get both beams of light (incident and reflected) to show up
> in media? I tried using photons and media.... but I cannot seem to get
> the reflected light to interact with the media....

This is not how raytracing works. You probably want radiosity.

bye,
  Chris
-- 
Christian Perle              E-mail:        chr### [at] tu-clausthalde
Am Galgensberg 4             WWW:        http://home.tu-clausthal.de/~incp/
38678 Clausthal/Germany      ComputerGuitarKitesBicyclesBeerPizzaRaytracing

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In article <399ad0eb@news.povray.org>, Christian Perle 
<inc### [at] rztu-clausthalde> wrote:

> This is not how raytracing works. You probably want radiosity.

Radiosity doesn't do this type of thing either.
I believe he is asking about the photon mapping patch, which does 
simulate this type of effect. However, I haven't looked at the most 
recent versions of the patch, so I can't really help with this problem...

-- 
Christopher James Huff
Personal: e-mail chr### [at] maccom, Web page http://homepage.mac.com/chrishuff/
TAG: e-mail chr### [at] tagpovrayorg, Web page http://tag.povray.org/

><>

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"Paul Daniel Jones" <pdj### [at] psuedu> wrote in message
news:399A871D.3F000619@psu.edu...
| How can i take a light source and reflect the light off a mirror type
| object and get both beams of light (incident and reflected) to show up
| in media? I tried using photons and media.... but I cannot seem to get
| the reflected light to interact with the media....

Same thing for me.  I tried and failed at it.  I had used the 'media'
keyword inside the photon block and did everything I could think of.  No
reflected light in the media, only on the walls, etc.  Could still be a
number problem, as in lack of enough sampling and such.  That and the fact
I've used a cylindrical spotlight, although trying with a regular spotlight
or point light source I hadn't had any luck seeing reflected light in the
media either.

Bob

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see Warps image on 3/27/00 in p.b.i......  I can't do this     :-(

Paul Daniel Jones wrote:

> How can i take a light source and reflect the light off a mirror type
> object and get both beams of light (incident and reflected) to show up
> in media? I tried using photons and media.... but I cannot seem to get
> the reflected light to interact with the media....
>
> --
> -------------------------------------------#
> Paul Daniel Jones
> 307 Chandlee Laboratory
> Penn State University
> 814-865-2090
> pdj### [at] psuedu
>
> http://research.chem.psu.edu/glassgrp/paul
> --------------------------------------------#

--
-------------------------------------------#
Paul Daniel Jones
307 Chandlee Laboratory
Penn State University
814-865-2090
pdj### [at] psuedu

http://research.chem.psu.edu/glassgrp/paul
--------------------------------------------#

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I'm missing Fe. and Mar. here, I was looking for those related postings too.
Warp was faking it with multiple cylinders if IIRC.

Bob

"Paul Daniel Jones" <pdj### [at] psuedu> wrote in message
news:399AF346.B1BBE5E7@psu.edu...
| see Warps image on 3/27/00 in p.b.i......  I can't do this     :-(

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On Wed, 16 Aug 2000 08:20:45 -0400, Paul Daniel Jones <pdj### [at] psuedu>
wrote:

>How can i take a light source and reflect the light off a mirror type
>object and get both beams of light (incident and reflected) to show up
>in media? I tried using photons and media.... but I cannot seem to get
>the reflected light to interact with the media....

Wasn't there something about a bug with cylinder lights and
photons/media? (in MegaPOV, that is)?


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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"Peter Popov" <pet### [at] usanet> wrote in message
news:b75mpssrej1ur2jukptiit62v5cjm44hhh@4ax.com...
| On Wed, 16 Aug 2000 08:20:45 -0400, Paul Daniel Jones <pdj### [at] psuedu>
| wrote:
|
| >How can i take a light source and reflect the light off a mirror type
| >object and get both beams of light (incident and reflected) to show up
| >in media? I tried using photons and media.... but I cannot seem to get
| >the reflected light to interact with the media....
|
| Wasn't there something about a bug with cylinder lights and
| photons/media? (in MegaPOV, that is)?

I guess cylinder lights don't work perfectly with photons to begin with
somehow.
That's not the trouble,  since I've tried it using a hole in the side of a
box and a point source.  So it's nothing to do with not working with
spotlights either.  Nathan has probably said before that media won't show a
reflected light, just not sure when or where if he did say so.

Bob

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In article <399b2031$1@news.povray.org>, "Bob Hughes" 
<per### [at] aolcom?subject=PoV-News:> wrote:

> Nathan has probably said before that media won't show a reflected 
> light, just not sure when or where if he did say so.

Actually, it *will* work. Media interaction is one of the features added 
in one of the more recent versions. It takes a lot of computation time 
and memory, but it works, and there was a laser-beam scene demonstrating 
it. There is also a sample scene demonstrating media-photon 
interaction(mediaphot.pov), maybe you should look at it for ideas.

I just am not familiar enough with the most recent version to figure out 
the problem.

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

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"Chris Huff" <chr### [at] maccom> wrote in message
news:chrishuff-9FE4ED.21050216082000@news.povray.org...
| In article <399b2031$1@news.povray.org>, "Bob Hughes"
| <per### [at] aolcom?subject=PoV-News:> wrote:
|
| > Nathan has probably said before that media won't show a reflected
| > light, just not sure when or where if he did say so.
|
| Actually, it *will* work. Media interaction is one of the features added
| in one of the more recent versions. It takes a lot of computation time
| and memory, but it works, and there was a laser-beam scene demonstrating
| it. There is also a sample scene demonstrating media-photon
| interaction(mediaphot.pov), maybe you should look at it for ideas.

Okay, I got it now, thanks so much for pointing out that sample scene file.
All I had to do is set reflection to on in the sphere and I saw the
spotlight shining back from it.  Great thing.  Now I have gotten a cylinder
spotlight to actually show up too, the weird thing is there wasn't really
any obvious reason for the not-working and working ways.  It's almost
metamorphosing the more I try to use it.  Typical thing because of so many
possible media settings I guess.  I at first even thought it was all because
of the sample file having a 'media on' in the photon block.   Not so.  I
tried with and without and get the laser light reflected in the media.
Curious to say the least.  I'm going to post this test render I have to
p.b.i. in a few minutes so it will prove to others it can be done.

Bob

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Bob Hughes <per### [at] aolcom?subject=pov-news:> wrote:
: I'm missing Fe. and Mar. here, I was looking for those related postings too.
: Warp was faking it with multiple cylinders if IIRC.

  FAKING!!! Who do you think I am? Those are TRUE photons. Period :)

  The image can be found here: http://www.cs.tut.fi/~warp/photontest.jpg

  And if you don't believe it's made with photons, here is the proof: The
source code:

#version Unofficial MegaPov 0.5;

#include "colors.inc"
#include "textures.inc"

#declare UsePhotons=yes;
global_settings
{
  max_trace_level 8
#if(UsePhotons)
  photons
  { count 20000
    autostop 0
    media 100
  }
#end  
}

box
{ <-4,-3,-1.5>,<8,3,1.5> hollow
  pigment { rgbt 1 }
  photons { pass_through }
  interior
  { media
    { intervals 10
      scattering { 1, rgb .5 extinction .01 }
      method 3
    }
  }
}

sphere
{ 0,70 inverse
  pigment
  { bozo color_map { [0 rgb 0][1 rgb <1,.5,0>] }
    scale <5,10,5>
  }
} 


camera
{ location -z*20 look_at 0 angle 35
}

light_source
{ <50,2,0> 1
  spotlight point_at y*2 radius .5 falloff .6
}
light_source
{ <100,100,-100>*.3 .8 media_interaction off
#if(UsePhotons)
  photons { reflection off refraction off }
#end
}

#declare MirrorBox=
union
{ difference
  { box { <-.5,-1.8,-1.8><.1,1.8,1.8> }
    box { <-.1,-1.5,-1.5><.11,1.5,1.5> }
    pigment { DMFWood4 }
  }
  box
  { <-.1,-1.5,-1.5><0,1.5,1.5>
    pigment { rgb 0 }
    finish { reflection 1 diffuse 0 ambient 0 }
#if(UsePhotons)
    photons
    { target
      refraction off
      reflection on
      ignore_photons
    }
#end
  }
}

object
{ MirrorBox
  rotate z*-45
  translate <-3,2,0>
}
object
{ MirrorBox
  rotate z*45
  translate <-3,-2,0>
}

box
{ <-.5,-1.5,-1.5><0,1.5,1.5>
  pigment { Cherry_Wood scale .5  }
  rotate z*180
  translate <5,-2,0>
}

sphere
{ 0,1.3 scale <.3,1,1>
  pigment { rgbf <.7,.9,1,.9> }
  finish { specular .5 reflection .1 }
  interior { ior 1.5 }
  translate <2,-2,0>
#if(UsePhotons)
    photons
    { target
      refraction on
      reflection on
    }
#end
}


-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:399bf23e@news.povray.org...
| Bob Hughes <per### [at] aolcom?subject=pov-news:> wrote:
| : Warp was faking it with multiple cylinders if IIRC.
|
|   FAKING!!! Who do you think I am? Those are TRUE photons. Period :)
|
|   The image can be found here: http://www.cs.tut.fi/~warp/photontest.jpg

Ahhh, further proof that my mind is a sieve.  Please excuse my ignorance.  I
was certain you had to resort to using cylinders for media containers for
that image (which I did remember).
Thanks greatly for posting that source.  I suppose the folded overlaps at
the mirrors was fixed by using enough media samples or in some such way?
I'm seeing plenty of change from one render to the next when altering the
intervals and/or samples in the scene file I'm checking all this out with.

Bob

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I copy-pasted this source and ran it in MegaPOV 0.5, everywhere I expect to see
media, all I get is black

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>I copy-pasted this source and ran it in MegaPOV 0.5, everywhere I
expect to see
>media, all I get is black

Renders fine for me.  Maybe you should check your .ini settings and make
sure you're not using quality 1 or something.

-Mike

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> Renders fine for me.  Maybe you should check your .ini settings and make
> sure you're not using quality 1 or something.

Believe me, I'm sure ;)

There was nothing specified, which means it should default to 9, which it
does indicate in the messages window, but still it was black. So I tried
putting +Q9 as command line parameter, still black. +Q10, still black.
Anyway, it's not too important.

On an unrelated note, you mentioned that you modified the source code to get
uv_mapping working for type 2 bicubic patches, could you send me the
files?(Actually to someone else ;) I know someone who has successfully
compiled POV (Win) and is willing to try with this modification. If you
agree, I'll let you know his e-mail so you can send it to him directly,
avoiding the middle man :)

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I uploaded a binary of the patch to povray.binaries.programming today,
so you can download it and use it right away.  Be sure to read the text
file so you'll know how to handle the new syntax.

-Mike

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> I uploaded a binary of the patch to povray.binaries.programming today,
> so you can download it and use it right away.  Be sure to read the text
> file so you'll know how to handle the new syntax.

Thank you Mike, wow you eliminated TWO middlemen :-)
<downloading>

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Also, I was wondering about your cloth system. *gasp* it's perfect! When I
did my tests a while back, with a little C program which would spit out a
triangle mesh, the numbers always ran off to infinity, and I got NaN mumble
grumble. I translated to POV script, it didn't have that tendancy, but it
took forever to parse.

I think my implementation was too naive. Are you using
deformation-constraints?

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> Also, I was wondering about your cloth system. *gasp* it's perfect!

It's not my cloth system, it's Hash Inc's.  I use their software,
animation master, for most of my modeling and wrote plugins to handle
export to .pov format.  Their homepage is www.hash.com

-Mike

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"Peter Popov" <pet### [at] usanet> wrote...
> On Wed, 16 Aug 2000 08:20:45 -0400, Paul Daniel Jones <pdj### [at] psuedu>
> wrote:
>
> >How can i take a light source and reflect the light off a mirror type
> >object and get both beams of light (incident and reflected) to show up
> >in media? I tried using photons and media.... but I cannot seem to get
> >the reflected light to interact with the media....
>
> Wasn't there something about a bug with cylinder lights and
> photons/media? (in MegaPOV, that is)?

Photons from cylinder lights behave if they were came from a spotlight (i.e.
the photon beams are not parallell, but spread out).

-Nathan

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