I'm having lots of fun with Nathan's new patch.  He and Ron should get a
kick out of this one (or anyone else who's read Jensen's papers).

There's a few artifacts that I think may be there because the glass is a
mesh. I'm still unsure of the brightness on the base, but I suspect it
may be that odd phenomenon of light getting brighter before the
fade_distance is reached.  Not sure though.

Took about 2 hours of fiddeling to come up with this, most of which was
learning how to use the patch - word to the wise: don't use photons on
infinite objects!

Render time was 38 minutes at 640x480 and AA 0.3.  

-Mike

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Attachments:
Download 'cognac.jpg' (40 KB)

Preview of image 'cognac.jpg'

Mike wrote:
> 
> I'm having lots of fun with Nathan's new patch.  He and Ron should get a
> kick out of this one (or anyone else who's read Jensen's papers).
> 
> There's a few artifacts that I think may be there because the glass is a
> mesh. I'm still unsure of the brightness on the base, but I suspect it
> may be that odd phenomenon of light getting brighter before the
> fade_distance is reached.  Not sure though.
> 
> Took about 2 hours of fiddeling to come up with this, most of which was
> learning how to use the patch - word to the wise: don't use photons on
> infinite objects!
> 
> Render time was 38 minutes at 640x480 and AA 0.3.
> 
> -Mike
> 
>   ------------------------------------------------------------------------
>  [Image]

What a dashing image! Can the patch be gotten from somewhere now?

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Can the patch be gotten from somewhere now?
> 


Look for yesterdays announcement in povray.programming from Nathan Kopp.


Hey Mikey ! Good stuff. I have a similar project under way. Time
to start dusting off all of those old glass objects that never quite
made it into a scene because the caustics were wrong.. <g>

-- 
Ken Tyler

mailto://tylereng@pacbell.net

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Did I expect a glass image? Yes :) I'm doing a brandy glass, BTW.
The brightening of the light is something to investigate. Try this: make a
glass sphere with ior 1. A strange effect. Now do ior 1.1. The caustic seems
far too bright and sharp. I'll investigate this a bit more before I start
bugging Nathan...

Margus

Mike wrote in message <36E6C207.4D987AFD@aol.com>...
>I'm having lots of fun with Nathan's new patch.  He and Ron should get a
>kick out of this one (or anyone else who's read Jensen's papers).
>
>There's a few artifacts that I think may be there because the glass is a
>mesh. I'm still unsure of the brightness on the base, but I suspect it
>may be that odd phenomenon of light getting brighter before the
>fade_distance is reached.  Not sure though.
>
>Took about 2 hours of fiddeling to come up with this, most of which was
>learning how to use the patch - word to the wise: don't use photons on
>infinite objects!
>
>Render time was 38 minutes at 640x480 and AA 0.3.
>
>-Mike

Post a reply to this message

>There's a few artifacts that I think may be there because the glass is a
>mesh. I'm still unsure of the brightness on the base, but I suspect it
>may be that odd phenomenon of light getting brighter before the
>fade_distance is reached.  Not sure though.
>


Is the foot of the glass flat? If so, what happens if you make it hollow?
Just an idea.

ingo

--
Met dank aan de muze met het glazen oog.

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I love the caustics.
About the glass: it seems awfully thick (tough cognac glass
I suppose?); is that necessary to achieve the clearly
visible caustic effect, or does it work with thin refractive
objects as well?

Julius

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I'm pretty sure I know why it is overly bright, but I'm not sure right now
exactly how to fix it.  Here's the problem:

     |______________|    glass
------------------------ ground

If the glass is just above the ground, photons will get deposited on
both surfaces.  But they are gathered independly from the scene geometry,
so you end up getting double the photons that you should get.  If you
set the "ignore_photons" flag in the glass, it shouldn't store photons
on the glass, so that should work as a workaround for now (speeds the
render time, too),

Sorry I didn't include any demo scenes.  Once you get a good shooting
density & gather density combination, you can usually just reuse that code
to get started with a new scene.

One way to get rid of artifacts is to increase the jitter amount.  If
that doesn't fix it, it probably is because your glass is a mesh.

Looks great, by the way!

-Nathan

Mike wrote:
> 
> I'm having lots of fun with Nathan's new patch.  He and Ron should get a
> kick out of this one (or anyone else who's read Jensen's papers).
> 
> There's a few artifacts that I think may be there because the glass is a
> mesh. I'm still unsure of the brightness on the base, but I suspect it
> may be that odd phenomenon of light getting brighter before the
> fade_distance is reached.  Not sure though.
> 
> Took about 2 hours of fiddeling to come up with this, most of which was
> learning how to use the patch - word to the wise: don't use photons on
> infinite objects!
> 
> Render time was 38 minutes at 640x480 and AA 0.3.
> 
> -Mike
> 
>   -------------------------------------------------------------------------------
>  [Image]

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Margus Ramst wrote:
> 
> Did I expect a glass image? Yes :) I'm doing a brandy glass, BTW.
> The brightening of the light is something to investigate. Try this: make a
> glass sphere with ior 1. A strange effect. Now do ior 1.1. The caustic seems

what strange effect?

> far too bright and sharp. I'll investigate this a bit more before I start
> bugging Nathan...

If it's too sharp, try a larger gather radius.  I've done all sorts of
tests with the brightness, so it _should_ be correct.

-Nathan

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now this is SOOOO great...
i have downloaded, three times.. (hmm, when NS says 502k of 270, something is
wrong) but not installed yet.. I'll get at it :-)


Mike wrote:
> 
> I'm having lots of fun with Nathan's new patch.  He and Ron should get a
> kick out of this one (or anyone else who's read Jensen's papers).
> 
> There's a few artifacts that I think may be there because the glass is a
> mesh. I'm still unsure of the brightness on the base, but I suspect it
> may be that odd phenomenon of light getting brighter before the
> fade_distance is reached.  Not sure though.
> 
> Took about 2 hours of fiddeling to come up with this, most of which was
> learning how to use the patch - word to the wise: don't use photons on
> infinite objects!
> 
> Render time was 38 minutes at 640x480 and AA 0.3.
> 
> -Mike
> 
>   --------------------------------------------------------------------------------
>  [Image]

-- 
//Spider 
( spi### [at] bahnhofse ) [ http://www.bahnhof.se/~spider/ ]
#declare life = rand(seed(42))*sqrt(-1);

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Rather NS than MS!


Steve

(as you can all see I've now got hold of the new browser version
settingw):

Spider wrote:
> 
> now this is SOOOO great...
> i have downloaded, three times.. (hmm, when NS says 502k of 270, something is
> wrong) but not installed yet.. I'll get at it :-)
> 
> Mike wrote:
> >
> > I'm having lots of fun with Nathan's new patch.  He and Ron should get a
> > kick out of this one (or anyone else who's read Jensen's papers).
> >
> > There's a few artifacts that I think may be there because the glass is a
> > mesh. I'm still unsure of the brightness on the base, but I suspect it
> > may be that odd phenomenon of light getting brighter before the
> > fade_distance is reached.  Not sure though.
> >
> > Took about 2 hours of fiddeling to come up with this, most of which was
> > learning how to use the patch - word to the wise: don't use photons on
> > infinite objects!
> >
> > Render time was 38 minutes at 640x480 and AA 0.3.
> >
> > -Mike
> >
> >   --------------------------------------------------------------------------------
> >  [Image]
> 
> --
> //Spider
> ( spi### [at] bahnhofse ) [ http://www.bahnhof.se/+AH4-spider/ ]
> #declare life = rand(seed(42))*sqrt(-1);

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