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From: Oldstench
Subject: Caustic issues
Date: 6 Jun 2002 15:30:26
Message: <3cffb852@news.povray.org>
Hello all,
    I have not posted in a long, long time, but now I am back doing some
raytracing and I need some help (go figure..). Anyway, I have been using Max
recently with the Brazil rendering system plug-in, and the results are nice,
but the fact is, I hate modeling in Max. So I have come back to Pov.
    My question is this...The first picture (caustinc_ring_2.jpg) represents
a render I did with Brazil to test its caustics, the second picture
(torus.jpg) is a photon image that I did in MegaPov just trying to get some
caustics as a start. But, as you can see..it looks like absolute crap. Why
is the ring glowing like that, and why are there no caustics in the familiar
parabolic shape?
    Thanks - Oldstench


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Attachments:
Download 'torus.jpg' (27 KB) Download 'caustic_ring_2.jpg' (25 KB)

Preview of image 'torus.jpg'
torus.jpg

Preview of image 'caustic_ring_2.jpg'
caustic_ring_2.jpg


 

From: bob h
Subject: Re: Caustic issues
Date: 6 Jun 2002 17:25:19
Message: <3cffd33f@news.povray.org>
"Oldstench" <tha### [at] hotmailcom> wrote in message
news:3cffb852@news.povray.org...
>     My question is this...The first picture (caustinc_ring_2.jpg)
represents
> a render I did with Brazil to test its caustics, the second picture
> (torus.jpg) is a photon image that I did in MegaPov just trying to get
some
> caustics as a start. But, as you can see..it looks like absolute crap. Why
> is the ring glowing like that, and why are there no caustics in the
familiar
> parabolic shape?

Your images posted reverse order of message text, but not hard to figure
that out.

I got an okay rendering done in the POV-Ray RC5 (beta 3.5), not sure what
happened to you with MegaPOV. I have seen the classic ring as rendered in
MegaPOV doing what you were trying though. Curiously, your attempt looks
more like radiosity, but it could just be a matter of 'count' and 'gather'
settings, possibly even 'ignore_photons' or something else entirely. I
couldn't say.
The attached image used v3.5, not MegaPOV, starting with just the Insert
Menu scene template for photons. Which means I used 'spacing 0.02' at first
is all, and it already did as expected. For this final image it was 0.03,
reflection only, area_light, max_trace_level 9. AA set to 0.01 depth of 5,
took 18m 36s for this 800MHz P3 while I did other things. Note that the AA
on the edges of the ring aren't exactly what I'd call great. Your Brazil
example looks very refined.

bob h


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Attachments:
Download 'reflectinglightring0.jpg' (8 KB)

Preview of image 'reflectinglightring0.jpg'
reflectinglightring0.jpg


 

From: Warp
Subject: Re: Caustic issues
Date: 6 Jun 2002 22:39:01
Message: <3d001cc4@news.povray.org>
How about this?


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Attachments:
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Preview of image 'test.jpg'
test.jpg


 

From: Apache
Subject: Re: Caustic issues
Date: 6 Jun 2002 22:50:34
Message: <3d001f7a$1@news.povray.org>
Cool!

I'm gonna try this for my little key...

--
Apache
POV-Ray Cloth experiments: http://geitenkaas.dns2go.com/experiments/
Email: apa### [at] yahoocom
ICQ: 146690431


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From: Halbert
Subject: Re: Caustic issues
Date: 7 Jun 2002 00:08:22
Message: <3d0031b6@news.povray.org>
That looks better than the Brazil image IMHO.
-- 


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From: Oldstench
Subject: Re: Caustic issues
Date: 7 Jun 2002 00:11:24
Message: <3d00326c$1@news.povray.org>
Warp <war### [at] tagpovrayorg> wrote in message news:3d001cc4@news.povray.org...
>   How about this?
>
>
Wow, that looks much better then mine, you are really good....

-Oldstench


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From: Slime
Subject: Re: Caustic issues
Date: 7 Jun 2002 00:34:15
Message: <3d0037c7@news.povray.org>
Wow, that's very nice, though the caustics don't appear quite as realistic
to me in this as they did in the brazil image. I'm sure it's just a matter
of a slightly different shape of ring, though.

 - Slime
[ http://www.slimeland.com/ ]


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From: Samuel Benge
Subject: POV 3.5 Version (ring.jpg 15.8kb)
Date: 7 Jun 2002 02:10:03
Message: <3D0052B2.8030101@caltel.com>
Hello. Here is the POV 3.5 version. I used no lights, only radiosity 
settings and an ambient sphere. Render time was 7m 45s

Here is the POV code:

global_settings{
  max_trace_level 50
  radiosity{
   error_bound .125  count 1575 nearest_count 10
   recursion_limit 1  normal on
   brightness 13.5  gray_threshold 0
   pretrace_start .08  pretrace_end .005
   always_sample on
  }
}

camera{location<0,30,-50> look_at 0 angle 40 }

sphere{<100,50,-50>,40
  pigment{rgb 1}
  finish{ambient 1}
  no_shadow double_illuminate
}

background{rgb .025}

plane{y,-2 pigment{rgb .7} finish{ambient 0} }

union{
  torus{11,1 translate y*1}
  torus{11,1 translate y*-1}
  cylinder{y*-1,y*1,12 open}
  cylinder{y*-1,y*1,10 open}
  pigment{rgb .1}
  finish{reflection .9 ambient 0}
}

Oldstench wrote:

>     My question is this...The first picture (caustinc_ring_2.jpg) represents
> a render I did with Brazil to test its caustics, the second picture
> (torus.jpg) is a photon image that I did in MegaPov just trying to get some
> caustics as a start. But, as you can see..it looks like absolute crap. Why
> is the ring glowing like that, and why are there no caustics in the familiar
> parabolic shape?
>     Thanks - Oldstench
> 
> 
> 


-- 
Samuel Benge

sbe### [at] caltelcom


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Attachments:
Download 'ring.jpg' (16 KB)

Preview of image 'ring.jpg'
ring.jpg


 

From: Apache
Subject: Re: POV 3.5 Version (ring.jpg 15.8kb)
Date: 7 Jun 2002 02:24:40
Message: <3d0051a8$1@news.povray.org>
why 'double_illuminate' ?

--
Apache
POV-Ray Cloth experiments: http://geitenkaas.dns2go.com/experiments/
Email: apa### [at] yahoocom
ICQ: 146690431


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From: Samuel Benge
Subject: Re: POV 3.5 Version (ring.jpg 15.8kb)
Date: 7 Jun 2002 09:46:18
Message: <3D00BDAA.8010701@caltel.com>
Apache wrote:

> why 'double_illuminate' ?


Because I'm silly and left that in by accident. I keep a test scene 
around for this type of thing; I had been testing a similar scene with 
actual photons, and the sphere was origially just used to give the ring 
a nice highlight. A light_source was inside the sphere, and the 
ambient_light was 0, so I had to give the sphere the double_illuminate 
and no_shadow flags.

-- 
Samuel Benge

sbe### [at] caltelcom


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