POV-Ray : Newsgroups : moray.win : Getting light to reflect Server Time: 10 Dec 2018 06:19:16 GMT
  Getting light to reflect (Message 1 to 10 of 14)  
Goto Latest 10 Messages Next 4 Messages >>>
From: alanr
Subject: Getting light to reflect
Date: 21 Feb 2011 14:05:01
Message: <web.4d627046854023081d72ddf90@news.povray.org>
Simple scene - black/white checkered plane with a chrome cube sat on it, lit by
a spotlight just covering the cube.

Where's the light I would expect to be reflected off the cube onto the unlit
adjacent floor plane?

I got everything I can find ticked and targetted (just on thoughts that have
come from all the help files I have been reading).  Spotlight is ticked for
reflection (not sure why I did that!)  Cube is ticked for reflection and target.
 Plane is ticked for reflection and target.  And Photons are enabled in the
scene settings.  Almost everything else is at its default setting.

Yet all I get from POVs render is a chrome cube sitting on a chequered floor
casting the expected shadow, but no light is reflecting off the sides of the
cube lit by the spotlight.  The cube reflects the image of the surrounding plane
just as you would expect a chrome cube to.

Got a feeling I've missed a rather important single issue here - but I'm darned
if I can find it!!


Post a reply to this message

From: Roman Reiner
Subject: Re: Getting light to reflect
Date: 21 Feb 2011 15:10:00
Message: <web.4d627f5c17f7bc164d4c2e5d0@news.povray.org>
Radiosity!


Post a reply to this message

From: Warp
Subject: Re: Getting light to reflect
Date: 21 Feb 2011 15:13:07
Message: <4d628103@news.povray.org>
alanr <nomail@nomail> wrote:
> Yet all I get from POVs render is a chrome cube sitting on a chequered floor
> casting the expected shadow, but no light is reflecting off the sides of the
> cube lit by the spotlight.  The cube reflects the image of the surrounding plane
> just as you would expect a chrome cube to.

  Light reflecting from objects to other objects is a hard problem.
POV-Ray implements the photon mapping algorithm for reflecting (and
refracting) surfaces, which is probably what you are looking for.
However, I'm not sure Moray supports this.

-- 
                                                          - Warp


Post a reply to this message

From: alanr
Subject: Re: Getting light to reflect
Date: 21 Feb 2011 15:35:00
Message: <web.4d6285f717f7bc161d72ddf90@news.povray.org>
"Roman Reiner" <lim### [at] gmxde> wrote:
> Radiosity!

Yep - thats turned on as is Photons, but still no refelction of the light from
the spotlight.


Post a reply to this message

From: Trevor G Quayle
Subject: Re: Getting light to reflect
Date: 21 Feb 2011 18:20:00
Message: <web.4d62ac2a17f7bc16b05ef170@news.povray.org>
"alanr" <nomail@nomail> wrote:
> "Roman Reiner" <lim### [at] gmxde> wrote:
> > Radiosity!
>
> Yep - thats turned on as is Photons, but still no refelction of the light from
> the spotlight.

You need to add:

photons{
  target
  reflection on
}
to your reflecting object

-tgq


Post a reply to this message

From: alanr
Subject: Re: Getting light to reflect
Date: 22 Feb 2011 20:10:00
Message: <web.4d64176817f7bc161d72ddf90@news.povray.org>
"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
> "alanr" <nomail@nomail> wrote:
> > "Roman Reiner" <lim### [at] gmxde> wrote:
> > > Radiosity!
> >
> > Yep - thats turned on as is Photons, but still no refelction of the light from
> > the spotlight.
>
> You need to add:
>
> photons{
>   target
>   reflection on
> }
> to your reflecting object
>
> -tgq

In POV I checked the scene file last submitted by Moray and it contains that
very same piece in the cube declaration with the addition 1.0 on the target
line.

So I am really at a loss as to what to do next.


Post a reply to this message

From: Robert McGregor
Subject: Re: Getting light to reflect
Date: 22 Feb 2011 22:05:01
Message: <web.4d64326d17f7bc1694d713cc0@news.povray.org>
"alanr" <nomail@nomail> wrote:
> So I am really at a loss as to what to do next.

Post a scene file so we can see what the underlying issue is...

Cheers,
Rob
-------------------------------------------------
www.McGregorFineArt.com


Post a reply to this message

From: Stephen
Subject: Re: Getting light to reflect
Date: 22 Feb 2011 22:43:04
Message: <4d643bf8$1@news.povray.org>
On 22/02/2011 10:02 PM, Robert McGregor wrote:
> Post a scene file so we can see what the underlying issue is...
>

A volunteer is worth ten pressed men. :-P

-- 
Regards
     Stephen


Post a reply to this message

From: Tim Cook
Subject: Re: Getting light to reflect
Date: 26 Feb 2011 02:37:28
Message: <4d686768$1@news.povray.org>
On 2011-02-21 09:13, Warp wrote:
> alanr<nomail@nomail>  wrote:
>> Yet all I get from POVs render is a chrome cube sitting on a chequered floor
>> casting the expected shadow, but no light is reflecting off the sides of the
>> cube lit by the spotlight.  The cube reflects the image of the surrounding plane
>> just as you would expect a chrome cube to.
>
>    Light reflecting from objects to other objects is a hard problem.
> POV-Ray implements the photon mapping algorithm for reflecting (and
> refracting) surfaces, which is probably what you are looking for.
> However, I'm not sure Moray supports this.

Are you wanting a visualisation of the beam of light in the space 
between the cube and the floor, or just the effect on the surface?  If 
the latter, radiosity is sufficient.  If the former, you need to add a 
scattering media surrounding the scene.  At this point, the light needs 
its photons checkbox ticked, the cube needs to be the target, and the 
floor needs collect set to 'on'.  Past that is a lot of fiddly 
trial-and-error.


Post a reply to this message

From: Warp
Subject: Re: Getting light to reflect
Date: 26 Feb 2011 18:18:55
Message: <4d69440f@news.povray.org>
Tim Cook <z99### [at] gmailcom> wrote:
> Are you wanting a visualisation of the beam of light in the space 
> between the cube and the floor, or just the effect on the surface?  If 
> the latter, radiosity is sufficient.

  Radiosity only does diffuse reflection, not specular (ie. mirror)
reflection, which is what photon mapping does. I got the impression
that the original poster wanted the light to reflect from a reflective
(mirror-like) object.

-- 
                                                          - Warp


Post a reply to this message

Goto Latest 10 Messages Next 4 Messages >>>

Copyright 2003-2008 Persistence of Vision Raytracer Pty. Ltd.