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From: Mark Wagner
Subject: Re: Afghan Sunrise (133K) - problem with star background
Date: 24 Sep 2000 03:06:52
Message: <39cda80c@news.povray.org>
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> color rgbft <1.0, 1.0, 1.0, 1.0, 1.0>
There's your problem. Remove either the F or the T component. Also, try
increasing the "diffuse" component of the planet's finish.
Mark
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From: sacrofts
Subject: Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight
Date: 24 Sep 2000 04:47:58
Message: <39cdbfbe@news.povray.org>
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I don't know if this will help, this is an adaptation from a tutorial I
was following. I vaguely remember some improvement in making the
absorption media and scattering media in separate declarations. The
tutorial advised dividing the color statement by the scale used to match
the radius of the atmosphere.
---code
#declare atmos = media { file://atmospheric scatter
scattering {4, rgb <.6,.5,1>/8280.5}
intervals 1 file://set to 10 for final
samples 2, 20
confidence 0.9999
variance 1/1000
density {
spherical
color_map{
[0, rgbf <0,0,0,1>]
[.075, rgbf <.75, .75, .75, 1>]
[.15 rgbf 1]
[.6, rgbf 1]
[.61, rgbf <0,0,0,1>]
[1, rgbf <0,0,0,1>]
}
}
scale 8280.5}
#declare atmos2 = media { file://atmospheric absorption
absorption rgb <.6, .5, 0>/8280.5
intervals 1 file://set to 20 for final
samples 2, 20
confidence 0.9999
variance 1/1000
density {
spherical
color_map{
[0, rgbf <0,0,0,1>]
[.075, rgbf <.75, .75, .75, 1>]
[.15 rgbf 1]
[.6, rgbf 1]
[.61, rgbf <0,0,0,1>]
[1, rgbf <0,0,0,1>]
}
}
scale 8280.5}
sphere {0, 8280.5 hollow file://atmosphere upper layer (low
refraction)
pigment{rgbt 1.0}
interior {ior 1.000292 media {atmos} media {atmos2}} file://050
}
---
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From: Bob Hughes
Subject: Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight
Date: 24 Sep 2000 16:58:17
Message: <39ce6ae9@news.povray.org>
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"sacrofts" <sac### [at] tinyonline co uk> wrote in message
news:39cdbfbe@news.povray.org...
I don't know if this will help, this is an adaptation from a tutorial I was
following. I vaguely remember some improvement in making the absorption
media and scattering media in separate declarations. The tutorial advised
dividing the color statement by the scale used to match the radius of the
atmosphere.
Do you have the URL to that tutorial available to post here? TIA if you do
because I'm sure people will want a look.
Reason I said absorption <0.5,0.5,0.5> was because of the uncertainty about
how it would fit in to begin with, so I was really just saying try
absorption.
Bob
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From: sacrofts
Subject: Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight
Date: 25 Sep 2000 08:37:31
Message: <39cf470b@news.povray.org>
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The tutorial is On Darcy Johnston's website, under the tutorials
section.
Here's the URL
http://www.geocities.com/SiliconValley/Sector/4317/
even following the tutorial, it took me a little while to realize what
changes I would need for my own image but the results, I think, are very
effective.
hope it helps
Steve
> Do you have the URL to that tutorial available to post here? TIA if
you do
> because I'm sure people will want a look.
> Reason I said absorption <0.5,0.5,0.5> was because of the uncertainty
about
> how it would fit in to begin with, so I was really just saying try
> absorption.
>
> Bob
>
>
>
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From: Bob Hughes
Subject: Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight
Date: 25 Sep 2000 17:46:05
Message: <39cfc79d@news.povray.org>
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Thanks, I didn't have that bookmarked.
"sacrofts" <sac### [at] tinyonline co uk> wrote in message
news:39cf470b@news.povray.org...
The tutorial is On Darcy Johnston's website, under the tutorials section.
Here's the URL
http://www.geocities.com/SiliconValley/Sector/4317/
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From: Jörg 'Yadgar' Bleimann
Subject: Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight
Date: 26 Sep 2000 02:27:41
Message: <39CFA447.E933F693@ndh.net>
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Hi Tracers!
sacrofts schrieb:
> The tutorial is On Darcy Johnston's website, under the tutorials section.
> Here's the URL
> http://www.geocities.com/SiliconValley/Sector/4317/
Yes, I tried absorption rgb <1, 0.5, 0> (according to my scattering rgb<0, 0.5, 1> and
reduced this filter, not translucency to 0... but Earth's surface still
remains dull and low in contrast! Also in Darcy's tutorial, I didn't find anything
about avoiding this effect... I browsed through the "finish" section of the
PoV-Ray manual, but it was also no help to me... is it avoidable at all or is it an
essential deficiency of raytracing?
See you in Khyberspace!
Yadgar
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From: sacrofts
Subject: Re. Afghan Sunrise (133K) - problem with star background
Date: 26 Sep 2000 14:12:13
Message: <39d0e6fd@news.povray.org>
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> Yes, I tried absorption rgb <1, 0.5, 0> (according to my scattering
rgb<0, 0.5, 1> and reduced this filter, not translucency to 0... but
Earth's surface still
> remains dull and low in contrast! Also in Darcy's tutorial, I didn't
find anything about avoiding this effect... I browsed through the
"finish" section of the
> PoV-Ray manual, but it was also no help to me... is it avoidable at
all or is it an essential deficiency of raytracing?
>
I'm beginning to wonder whether this effect is what is supposed to
happen to the light as it travels through the simulated atmosphere. For
a similar scene I'm working on, I'm afraid I cheated and used several
light sources, one the source of the rising sun, another shadowless
light to rim light the atmosphere and a bit of artistic license to add a
second sun into the scene from behind the viewer (well I'm not doing
earth!!) But I guess there's no harm in making use of shadowless lights
in this way.
Maybe some control over the contrast could be gained by using a
color_map on your spherical density, this should simulate a thinning of
the atmosphere from the planet's surface to the atmosphere's edge (index
1.0 on the color_map).
One thing my own image is lacking is a descent glow over the planet's
limb, any ideas?
Steve
website being built:
http://website.lineone.net/~sacrofts/home.htm
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From: Mark Wagner
Subject: Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight
Date: 27 Sep 2000 01:23:49
Message: <39d18465@news.povray.org>
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>Yes, I tried absorption rgb <1, 0.5, 0> (according to my scattering rgb<0,
0.5, 1> and reduced this filter, not translucency to 0... but Earth's
surface still
>remains dull and low in contrast! Also in Darcy's tutorial, I didn't find
anything about avoiding this effect... I browsed through the "finish"
section of the
>PoV-Ray manual, but it was also no help to me... is it avoidable at all or
is it an essential deficiency of raytracing?
Try increasing the "diffuse" component of the finish of the planet's surface
to something in the 2.0 to 6.0 range.
Mark
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From: Yadgar
Subject: Re: Afghan Sunrise (133K) - stars now correct, but surface in twilight
Date: 27 Sep 2000 22:22:50
Message: <39D23BB6.ABC2D76B@ndh.net>
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Hi Tracers!
Mark Wagner schrieb:
> >Yes, I tried absorption rgb <1, 0.5, 0> (according to my scattering rgb<0,
> 0.5, 1> and reduced this filter, not translucency to 0... but Earth's
> surface still
> >remains dull and low in contrast! Also in Darcy's tutorial, I didn't find
> anything about avoiding this effect... I browsed through the "finish"
> section of the
> >PoV-Ray manual, but it was also no help to me... is it avoidable at all or
> is it an essential deficiency of raytracing?
>
> Try increasing the "diffuse" component of the finish of the planet's surface
> to something in the 2.0 to 6.0 range.
>
> Mark
Thank you all for your advice, but in the meantime I found out, that in my
recent Iran/Afghanistan-from-orbit scene the (invisible, I commented out the
lensflare for convenience) sun was in fact very low, so that Earth surface just
could not be really bright.
I then moved the camera several dozen latitude degrees eastward into noon
sunlight over Eastern Siberia, and now I got the desired result!
Now I'm fiddling around with various texture patterns and noise modifiers to get
halfway realistic cloud swirls. The cloud layer is in fact a third concentric
sphere around my Earth, its surface 0.005 units (5 kms in my chosen scale) above
Earth surface, a comparatively simple color black-and-white (with a not too soft
transition between) map with filter values counter-corresponding to brightness
(black=1, white 0), so that the Earth surface is only hidden by the white clouds
(which cast nice shadows) ... at least, I found out that irrespective of
distribution patterns the white cloud areas need some relief to emulate the
cumuli structures, so I also have to add a bumpmap...
More on my cloud experiments later!
See you in Khyberspace!
Yadgar
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Bill DeWitt wrote:
>
> ...but I wanted Ken to note the proper way to indent and arrange
> code.
You talking to me boy ?
I will continue to produce my POV-Ray code as I see fit. I will not
conform. I don't want to and I don't have to.
--
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
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