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From: IMBJR
Subject: Glass sphere comparison between Bryce and POV
Date: 24 Aug 2002 16:19:43
Message: <3d67ea5f@news.povray.org>
I think the anti-aliasing is the clue here. Must learn how to get good
results.

However, the obvious difference between the 2 might be another clue.

This has at least made me conscious of something Bryce does in the way it
handles certain attributes.


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Download 'thing_two.jpg' (47 KB) Download 'thing_one.jpg' (53 KB)

Preview of image 'thing_two.jpg'
thing_two.jpg

Preview of image 'thing_one.jpg'
thing_one.jpg


 

From: hughes b
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 24 Aug 2002 16:41:32
Message: <3d67ef7c@news.povray.org>
"IMBJR" <no### [at] spamhere> wrote in message news:3d67ea5f@news.povray.org...
> I think the anti-aliasing is the clue here. Must learn how to get good
> results.
>
> However, the obvious difference between the 2 might be another clue.

Dang! Clues and more clues. Am I going to be guessing what's what from now
on! Used to be a image file here was either POV-made or a photo.

Only joking.

Well, I can't figure out why the 2nd image (thing 1) has both antialised and
aliased look to the checkered room. The floor looks like no AA, the wall has
AA...?? Seems like one of those instances where the color difference wasn't
enough for the threshold or something. Anyway, I hate to say it but is that
POV there, thing #1? And if so, looks like conserve_energy wan't applied.

Have a good question for you. When Bryce is used, is that ray tracing, or
scanline rendering only?


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From: IMBJR
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 24 Aug 2002 17:52:58
Message: <3d68003a@news.povray.org>
hughes b <omn### [at] charternet> wrote in message
news:3d67ef7c@news.povray.org...
> "IMBJR" <no### [at] spamhere> wrote in message news:3d67ea5f@news.povray.org...
> > I think the anti-aliasing is the clue here. Must learn how to get good
> > results.
> >
> > However, the obvious difference between the 2 might be another clue.
>
> Dang! Clues and more clues. Am I going to be guessing what's what from now
> on! Used to be a image file here was either POV-made or a photo.
>
> Only joking.
>
> Well, I can't figure out why the 2nd image (thing 1) has both antialised
and
> aliased look to the checkered room. The floor looks like no AA, the wall
has
> AA...?? Seems like one of those instances where the color difference
wasn't
> enough for the threshold or something. Anyway, I hate to say it but is
that
> POV there, thing #1? And if so, looks like conserve_energy wan't applied.

Yes. Thing 1 is POV. I'm new to the idea of conserve_energy so I didn't use
it.

The fresnel option was also turned off because it was starting to eliminate
reflections that Bryce keeps. I struggled to get as much reflection as Bryce
has as it is - the lower part of the POV sphere was very reluctant to reveal
too much of the floor.

I ended up using phong instead of specular as specular was too bright; a
phong mark looked far more Bryce-like.

>
> Have a good question for you. When Bryce is used, is that ray tracing, or
> scanline rendering only?

I've just checked various bits of documentation and I'm now confused.

I understand raytracing to be the projection of rays from the camera into a
scene, which the Bryce documentation implies is what is happening. However,
watching Bryce at work suggests scanline rendering (line-by-line rendering).
But that's what POV is doing too, right? Wrong?

I always understood POV to raytrace as Bryce does, but this scanline
business seems to suggest otherwise.

How strange. I've never given this any thought before and now its got me!



>
>
>


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From: Hugo
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 24 Aug 2002 18:44:08
Message: <3d680c38$1@news.povray.org>
There are no shadow in the POV version and AA behaves strangely. Here are
some suggestions that MIGHT improve things:

Lower the ambient.
Increase brilliance for checkered planes.

Use fade_distance and fade_power for the light_source. Set fade_distance to
1 and fade_power to 2. Use a high strength of light (rgb much over 1) to
compensate for the low fade_distance.

Converse_energy is probably important.

Small note about the shadow: It could be that Bryce has "caustics" turned on
by default. At least this keyword exsists in POV and will affect the shadow.
(Not to be confused with photons).

Keep us updated please.. You know, you can't leave us hanging in the air,
when the POV version still doesn't beat Bryce!

Regards,
Hugo


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From: Xplo Eristotle
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 24 Aug 2002 21:27:51
Message: <3d683297@news.povray.org>
IMBJR wrote:
> I think the anti-aliasing is the clue here. Must learn how to get good
> results.
> 
> However, the obvious difference between the 2 might be another clue.
> 
> This has at least made me conscious of something Bryce does in the way it
> handles certain attributes.

I had to make some wild guesses about your scene layout, but how's this?

-Xplo


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Attachments:
Download 'bryceglass.png' (46 KB)

Preview of image 'bryceglass.png'
bryceglass.png


 

From: IMBJR
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 25 Aug 2002 06:04:37
Message: <3d68abb5@news.povray.org>
Xplo Eristotle <xpl### [at] infomagicnet> wrote in message
news:3d683297@news.povray.org...
> IMBJR wrote:
> > I think the anti-aliasing is the clue here. Must learn how to get good
> > results.
> >
> > However, the obvious difference between the 2 might be another clue.
> >
> > This has at least made me conscious of something Bryce does in the way
it
> > handles certain attributes.
>
> I had to make some wild guesses about your scene layout, but how's this?

Yes, very close. That's a good repro without knowing where everything was.

>
> -Xplo
>


----------------------------------------------------------------------------
----


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From: Mike Williams
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 25 Aug 2002 08:10:03
Message: <v6MgzGAeiIa9EwaN@econym.demon.co.uk>
Wasn't it IMBJR who wrote:
>I think the anti-aliasing is the clue here. Must learn how to get good
>results.
>
>However, the obvious difference between the 2 might be another clue.
>
>This has at least made me conscious of something Bryce does in the way it
>handles certain attributes.

One thing I noticed in "thing_two.jpg" (the first of the two images) is
that the anti-aliassing is only working in the horizontal direction.

I know that POV always remembers the info calculated for the previous
line, so that it can perform anti-aliassing in both directions. I guess
Bryce can be told to switch to one-dimensional anti-aliassing, since in
your previous POV/Bryce images they both seem to have anti-aliassing in
both directions.

-- 
Mike Williams
Gentleman of Leisure


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From: Hugo
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 25 Aug 2002 09:37:23
Message: <3d68dd93$1@news.povray.org>
> One thing I noticed in "thing_two.jpg" (the first of the two images)
> is that the anti-aliassing is only working in the horizontal direction.
> ....
> I guess Bryce can be told to switch to one-dimensional AA ...

Now I'm confused. Are you saying "thing_two.jpg" is from POV and the
brightest sphere is from Bryce? Then you have already improved the bryce
look considerably!  The darker ball is much more realistic.

Regards,
Hugo


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From: Mike Williams
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 25 Aug 2002 14:28:14
Message: <Ig1JlAA6ESa9Ew+k@econym.demon.co.uk>
Wasn't it Hugo who wrote:
>> One thing I noticed in "thing_two.jpg" (the first of the two images)
>> is that the anti-aliassing is only working in the horizontal direction.
>> ....
>> I guess Bryce can be told to switch to one-dimensional AA ...
>
>Now I'm confused. Are you saying "thing_two.jpg" is from POV and the
>brightest sphere is from Bryce? Then you have already improved the bryce
>look considerably!  The darker ball is much more realistic.

I thought it had been established that thing_one (the second image) was
POV. I believe POV always does antialliasing in both directions.

-- 
Mike Williams
Gentleman of Leisure


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From: Hugo
Subject: Re: Glass sphere comparison between Bryce and POV
Date: 25 Aug 2002 16:32:38
Message: <3d693ee6$1@news.povray.org>
> >Now I'm confused. Are you saying "thing_two.jpg" is from POV
> > and thebrightest sphere is from Bryce? Then you have already
> > improved the bryce look considerably!  The darker ball is much
> > more realistic.
>
> I thought it had been established that thing_one (the second image)
> was POV. I believe POV always does antialliasing in both directions.

Yes it does, but .... but ... "thing_two" (the first image, with the dark
ball) is the image with AA in both directions, so it must be POV..


Hugo


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