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"Thomas Lake" <tla### [at] home com> wrote in message
news:3b5e4c11@news.povray.org...
> Well I finally found rad settings that improved the image and rendered in
a
> reasonable amount of time. I used an error_bound of 0.4 and decreased the
> pretrace start to 0.01 and pretrace end to 0.0025. This is the version
that
> will become my poster.
>
Have you tried a higher pretrace_start setting ? I've found whacking it
right up to 1.00 for final renders gets rid of ugly rad artifacts...
--
Scott Hill.
Software Engineer.
E-Mail : sco### [at] innocentcom
Pandora's Box : http://www.pandora-software.com
*Everything in this message/post is purely IMHO and no-one-else's*
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Scott Hill wrote:
> Have you tried a higher pretrace_start setting ? I've found whacking it
> right up to 1.00 for final renders gets rid of ugly rad artifacts...
Actually all I've been using for a while is pretrace_start = pretrace_end = 1
(in Megapov). The strangest thing is that I don't know what I'm losing doing
that.
G.
--
**********************
http://www.oyonale.com
**********************
Graphic experiments
Pov-ray gallery
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"Gilles Tran" <tra### [at] inapginrafr> wrote in message
news:3B5F250E.276DA256@inapg.inra.fr...
> Scott Hill wrote:
>
> > Have you tried a higher pretrace_start setting ? I've found whacking it
> > right up to 1.00 for final renders gets rid of ugly rad artifacts...
>
> Actually all I've been using for a while is pretrace_start = pretrace_end
= 1
> (in Megapov). The strangest thing is that I don't know what I'm losing
doing
> that.
>
Well, the way I understand it, the rad pretrace settings are similar to
the mosaic preview settings, i.e. they're expressed as a percentage of the
image width... So with start=end=1.00 you're saying "take one sample at the
image width and do no more"... I think... Yeah, I'm pretty sure this
correct - if you set pretrace_start to 1.00 and pretrace_end to 0.50 you'll
see the rad pretrace stage gets down to 'blocks' half the width of the image
before the final pass starts... 0.25 ends at blocks 1/4 of the width and so
on... So, it seems to follow that, for max rad quality you need to set
pretrace_start=1.00 and pretrace_end=1/imagewidth... Having said that, the
'blocks' start getting kind of blurry when they get to around 4x4pixels, no
matter what the pretrace_end setting is...
--
Scott Hill.
Software Engineer.
E-Mail : sco### [at] innocentcom
Pandora's Box : http://www.pandora-software.com
*Everything in this message/post is purely IMHO and no-one-else's*
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Yes, I'd buy that one when my boat comes in.
Alf
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> Yes, I'd buy that one when my boat comes in.
Hehe thanks:-) That will be 1,000,000$ please.
> Alf
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"Scott Hill" <sco### [at] innocentcom> wrote in message
news:3b5f5261@news.povray.org...
> "Gilles Tran" <tra### [at] inapginrafr> wrote in message
> news:3B5F250E.276DA256@inapg.inra.fr...
> > Scott Hill wrote:
> >
> > > Have you tried a higher pretrace_start setting ? I've found whacking
it
> > > right up to 1.00 for final renders gets rid of ugly rad artifacts...
> >
> > Actually all I've been using for a while is pretrace_start =
pretrace_end
> = 1
> > (in Megapov). The strangest thing is that I don't know what I'm losing
> doing
> > that.
> >
>
> Well, the way I understand it, the rad pretrace settings are similar
to
> the mosaic preview settings, i.e. they're expressed as a percentage of the
> image width... So with start=end=1.00 you're saying "take one sample at
the
> image width and do no more"... I think... Yeah, I'm pretty sure this
> correct - if you set pretrace_start to 1.00 and pretrace_end to 0.50
you'll
> see the rad pretrace stage gets down to 'blocks' half the width of the
image
> before the final pass starts... 0.25 ends at blocks 1/4 of the width and
so
> on... So, it seems to follow that, for max rad quality you need to set
> pretrace_start=1.00 and pretrace_end=1/imagewidth... Having said that, the
> 'blocks' start getting kind of blurry when they get to around 4x4pixels,
no
> matter what the pretrace_end setting is...
Hmm this is an interesting discusion, I've been wondering what these
settings really do, the pov docs arn't much help here. I'll have to do some
testing to see how different settings affect different images, but I'm not
going to play with this image any more.
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Thomas Lake wrote:
>
> Hmm this is an interesting discusion, I've been wondering what these
> settings really do, the pov docs arn't much help here. I'll have to do some
> testing to see how different settings affect different images, but I'm not
> going to play with this image any more.
In general lower pretrace_end leads to better quality, but very often
1/image_width is more than necessary. It should correspond to
error_bound, there meaning a lower error_bound should have a lower
pretrace_end.
Some suggested values are:
error_bound 3 => pretrace_end 0.08
error_bound 1 => pretrace_end 0.02
error_bound <1 => pretrace_end 0.01
but they only give a rough idea, for low error_bounds you will probably
have to try what leads to the best quality/speed ratio.
Christoph
--
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other
things on: http://www.schunter.etc.tu-bs.de/~chris/
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"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:3B5FC21F.DF935776@gmx.de...
> Thomas Lake wrote:
> >
> > Hmm this is an interesting discusion, I've been wondering what these
> > settings really do, the pov docs arn't much help here. >
> In general lower pretrace_end leads to better quality, but very often
> 1/image_width is more than necessary. It should correspond to
> error_bound
This is one of the aspects of radiosity that I just don't understand -
from reading the docs I don't see how or why error_bound and pretrace_end
are related...
--
Scott Hill.
Software Engineer.
E-Mail : sco### [at] innocentcom
Pandora's Box : http://www.pandora-software.com
*Everything in this message/post is purely IMHO and no-one-else's*
Post a reply to this message
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Scott Hill wrote:
>
> This is one of the aspects of radiosity that I just don't understand -
> from reading the docs I don't see how or why error_bound and pretrace_end
> are related...
>
I don't have a precise technical explanation, but with high error_bound
lower pretrace_end values have no effect. In other words, if you use
1/image_width, you will be on the safe side concerning quality, but the
last pretrace steps are totally unnecessary for the result.
Christoph
--
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other
things on: http://www.schunter.etc.tu-bs.de/~chris/
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> In general lower pretrace_end leads to better quality, but very often
> 1/image_width is more than necessary. It should correspond to
> error_bound, there meaning a lower error_bound should have a lower
> pretrace_end.
But, if so, how Gilles radiosity scenes look so nice? I my self tried
just now pretrace start and end to 1 with my current irtc entry, and the
result is a 30% faster than with the recommended settings. And,
strangely, the result seems to be more "natural" although it has some
artifacts. Perhaps for "dirty" scenes it adds some irregularity that
looks better to our "anti-perfectly-clean" minds. In any case, I would
stick to 1 at least for that concrete scene, cause it renders faster and
the result looks slightly better.
--
Jaime Vives Piqueres
La Persistencia de la Ignorancia
http://www.ignorancia.org/
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