POV-Ray: Newsgroups: povray.general: How should single dimension area lights work??

POV-Ray : Newsgroups : povray.general : How should single dimension area lights work??		Server Time 6 Aug 2024 17:02:24 EDT (-0400)

From: Rich
Subject: How should single dimension area lights work??
Date: 11 Feb 2002 23:23:13
Message: <Xns91B2D98E9F637spammindspringcom@204.213.191.226>

Help!  I'm trying to simulate tube lighting, and I'm not understanding 
the results I get from a single dimension area light.  Given the following 
scene, how come I don't get a line of illumination?

camera { 
  location <1, 20, -20> 
  direction 1.5*z 
  right x*image_width/image_height 
  look_at 0
}

light_source { 
  <0,1,0> rgb 1
  area_light <20,0,0>,<0,0,1>,20,1 
  adaptive 1 jitter
}

plane { y, 0 pigment { color rgb <0,0,1> } }
plane { z, 1 pigment { color rgb <1,0,0> } }


-- 
Rich Allen
(Remove SPAM from my address to reply by e-mail)

Post a reply to this message

From: Warp
Subject: Re: How should single dimension area lights work??
Date: 11 Feb 2002 23:26:59
Message: <3c689993@news.povray.org>

Rich <SrP### [at] ricoswebcom> wrote:
: how come I don't get a line of illumination?

  Area lights affect *only* shadow calculations. Nothing else.

-- 
#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 -

Post a reply to this message

From: Rich
Subject: Re: How should single dimension area lights work??
Date: 11 Feb 2002 23:43:24
Message: <Xns91B2DCFAB7B23spammindspringcom@204.213.191.226>

Warp <war### [at] tagpovrayorg> wrote in news:3c689993@news.povray.org:

> Rich <SrP### [at] ricoswebcom> wrote:
>: how come I don't get a line of illumination?
> 
>   Area lights affect *only* shadow calculations. Nothing else.

  Ah.  Ok, I see where it says this in the docs.  Sorry I missed that 
before posting, but it seems so counter-intuitive; if the illumination 
doesn't match the shadows, area_lights become very limited in their 
usefulness.
  So how do I get a smooth line of illumination?  A simple array of point 
lights doesn't work; either there aren't enough lights to provide smooth 
illumination or there are too many to render in a reasonable time.  <sigh>

-- 
Rich Allen
(Remove SPAM from my address to reply by e-mail)

Post a reply to this message

From: bob h
Subject: Re: How should single dimension area lights work??
Date: 12 Feb 2002 04:12:20
Message: <3c68dc74@news.povray.org>

"Rich" <SrP### [at] ricoswebcom> wrote in message
news:Xns### [at] 204213191226...
>   So how do I get a smooth line of illumination?  A simple array of point
> lights doesn't work; either there aren't enough lights to provide smooth
> illumination or there are too many to render in a reasonable time.  <sigh>

Takes a workaround to get area highlighting.  By reflection of the highly
ambient light object or media can act as the glowing shape of a light.  glow
in MegaPOV is good too.  Thing is, nothing I know of makes for a perfect
true area light.  A string of point lights with short fade distances to
speed it up only works well on nearby things.  Radiosity can do okay on the
nearby surfaces too.

bob h

Post a reply to this message

From: Rich
Subject: Re: How should single dimension area lights work??
Date: 12 Feb 2002 18:03:41
Message: <Xns91B3A361D11D6spammindspringcom@204.213.191.226>

"bob h" <omn### [at] charternet> wrote in news:3c68dc74@news.povray.org:

> Takes a workaround to get area highlighting.  By reflection of the
> highly ambient light object or media can act as the glowing shape of a
> light.

Hmm, I'll have to try this.  A cylinder with a really large ambient value, 
along with radiosity, might give me the effect I'm after.  Thanks!

-- 
Rich Allen
(Remove SPAM from my address to reply by e-mail)

Post a reply to this message