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Kari Kivisalo wrote:
>
> Ken wrote:
> >
> > No, I don't. I have never seen any situation in real life that this
> > would represent.
>
> How can you compare then?
Simple. In front of me I place a solid red ball on a white piece of paper
with a fairly bright light shining on it. I see a fairly dark shadow but
absolutely zero evedence of red color bleed. I now repeat the experiment
with other colored objects. Again no color bleed.
Are we trying to mimic real life or photometric experiments ?
I remain unconvinced.
--
Ken Tyler
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From: Christoph Hormann
Subject: Re: Radiosity2-Now with "ambient Normals"
Date: 21 Mar 2001 06:09:45
Message: <3AB88BF9.D2323D7A@gmx.de>
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Ken wrote:
>
> Simple. In front of me I place a solid red ball on a white piece of paper
> with a fairly bright light shining on it. I see a fairly dark shadow but
> absolutely zero evedence of red color bleed. I now repeat the experiment
> with other colored objects. Again no color bleed.
>
I just tried the same with a few colored pencils and a red peace of cloth
and saw quite a lot of bleeding. Sadly i have no digital camera here to
show it :-) It's cloudy today and the pencils have a fairly shiny surface,
but i really think it is quite realistic.
Christoph
--
Christoph Hormann <chr### [at] gmx de>
IsoWood include, radiosity tutorial, TransSkin and other
things on: http://www.schunter.etc.tu-bs.de/~chris/
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in <3AB889A4.D0C40829@pacbell.net> Ken wrote:
>Simple. In front of me I place a solid red ball on a white piece of
>paper with a fairly bright light shining on it.
Dim the light, or better just use the daylight. On the side where the
light comes from the paper has a red tint.
I could make some foto's if you want to be convinced.
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
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ingo wrote:
>
> I could make some foto's if you want to be convinced.
Is Ken trolling us?
______________________________________________________________________
Kari Kivisalo http://www.kivisalo.net
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From: Jan Walzer
Subject: Re: Radiosity2-Now with "ambient Normals"
Date: 21 Mar 2001 07:03:26
Message: <3ab8988e@news.povray.org>
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I don't think the problem was due to the background{} ...
If you turn off the normals in radiosity, you will get a similar (or
the same) result ...
the "ambient-normals" of the sphere just scramble the reflections, so
you can't recognize them ...
--
background{rgb 1}camera{location<1,5,-2>look_at 0}#macro
m(a,b,i)#local d=(b-a)
/8;#local
e=vcross(d,y);#if(i)m(a-e,a+e+2*d,i-1)m(a+e,a+2*d-e,i-1)m(a+3*d-e,a+e
+3*d,i-1)m(a+3*d-e,a+5*d-e,i-1)m(a+6*d-e,a+e+6*d,i-1)m(a+8*d-e,a+e+8*d
,i-1)#else
cylinder{a,b,vlength(d)/3 pigment{rgb 0}}#end#end m(-4*x,2*x,4) // Jan
Walzer
"Kari Kivisalo" <kar### [at] kivisalonet> schrieb im Newsbeitrag
news:3AB88380.89C707E7@kivisalo.net...
> Ken wrote:
> >
> > No, I don't. I have never seen any situation in real life that
this
> > would represent.
>
> How can you compare then?
>
> I have seen several photometric images of physical setups and
> corresponding rad simulations in IEEE and other publications
> which clearly show the validity of radiosity. There are differences
> in implementations, like noise in the ray based radiosity, but the
> basic concept is solid.
>
> The problem with all radiosity implementations is that there are too
> many cryptic parameters to tweak so users in general use non optimal
> setup which ruins the simulation. There is an EU project ARCADE
which
> tries to automate the parameter tweak phase among other things so
that
> you don't have to be "Certified Radiosity Technician" to produce
good
> results. http://www-imagis.imag.fr/ARCADE/
>
> This particular scene is a poor choice for meaasuring how realistic
> the simulation is for two reasons. The "sky" emits the same amount
of
> "energy" as the "sun". Nobody has ever seen this situation so it's a
> bit difficult to compare. The scene is also uniform in all
directions.
>
>
> There is something funny going on with background{} and radiosity.
> I rendered the same scene enclosed in a sphere and the anomaly at
> the bottom of the sphere disappeared.
> http://hammer.prohosting.com/~kkivisal/sphere.jpg
>
>
>
______________________________________________________________________
> Kari Kivisalo
http://www.kivisalo.net
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Jan Walzer wrote:
>
> I don't think the problem was due to the background{} ...
> If you turn off the normals in radiosity, you will get a similar (or
> the same) result ...
This was rendered with normal on.
______________________________________________________________________
Kari Kivisalo http://www.kivisalo.net
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in <3AB890EB.5B9EB478@kivisalo.net> Kari Kivisalo wrote:
>Is Ken trolling us?
>
Or his evil brother ...
(_)
(") W
/ \ |
/ . \ /
\ /`
_M_
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
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ingo wrote:
>
> in <3AB890EB.5B9EB478@kivisalo.net> Kari Kivisalo wrote:
>
> >Is Ken trolling us?
> >
> Or his evil brother ...
>
> (_)
> (") W
> / \ |
> / . \ /
> \ /`
> _M_
Nice pic. I especially like the effect of radiosity here. But can you
post the scene file?
(heh heh heh)
-Xplo
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From: Nekar Xenos
Subject: Re: Radiosity2-Now with "ambient Normals"
Date: 22 Mar 2001 10:38:27
Message: <3aba1c73@news.povray.org>
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It's because the sky is simulated. The light that illuminates sky comes from
the sun. So the blue intensity in the sky should never be higher than the
blue intensity of the sun e.g. sun: rgb ( 1.0, 0.9, 0.5 ) might have a sky
of rgb ( 0.1, 0.3, 0.5 ) and not rgb ( 0.1, 0.3, 1.0 ). (I don't know what
the settings are in the pic)
I think absorbing media and scattering media might make a more 'real' sky.
BTW, has anyone tried making sky with media before?
Nekar
"Jan Walzer" <jan### [at] lzernet> wrote in message
news:3ab7aef0@news.povray.org...
> Hehe ... I asked this myself ...
> The Heaven is blue ...
> so the most ambient is blue ...
> The sun is yellow ...
> so where the sun hits the sphere, there is the ambient and the sun
> (blue + yellow) that gives white ...
>
> The shadow of the sphere, that is not lit by the sun is blue, because
> of the ambient ...
> below the sphere there is no ambient, but the sun brightens some parts
> ...
> so it gets yellow ...
>
> You understand ?
>
> --
> background{rgb 1}camera{location<1,5,-2>look_at 0}#macro
> m(a,b,i)#local d=(b-a)
> /8;#local
> e=vcross(d,y);#if(i)m(a-e,a+e+2*d,i-1)m(a+e,a+2*d-e,i-1)m(a+3*d-e,a+e
> +3*d,i-1)m(a+3*d-e,a+5*d-e,i-1)m(a+6*d-e,a+e+6*d,i-1)m(a+8*d-e,a+e+8*d
> ,i-1)#else
> cylinder{a,b,vlength(d)/3 pigment{rgb 0}}#end#end m(-4*x,2*x,4) // Jan
> Walzer
>
>
>
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In article <3aba1c73@news.povray.org>, "Nekar Xenos"
<vir### [at] iconcoza> wrote:
> I think absorbing media and scattering media might make a more 'real' sky.
> BTW, has anyone tried making sky with media before?
It has been done by several people. I've had fairly good results
producing a sunset by using scattering media in several "shells" and a
large sphere for the land. However, MegaPOV's sampling method 2 or 3 is
almost absolutely necessary for this.
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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