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I've been to this site countless times but never noticed that this page
was so detailed :
http://freespace.virgin.net/hugo.elias/models/m_clouds.htm
Question for the POV gurus : is it possible to implent this either as a
macro or directly in the POV code ?
G.
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Gilles Tran wrote:
>
> I've been to this site countless times but never noticed that this page
> was so detailed :
> http://freespace.virgin.net/hugo.elias/models/m_clouds.htm
> Question for the POV gurus : is it possible to implent this either as a
> macro or directly in the POV code ?
> G.
This technique seems to combine several renderings to a final picture. The
Povray equivalent would be using the post_process function.
For example: seperate rendering of clouds, sky gradient, sun glow (media), lens
flare and combining them with post_process.
It's definitely worth trying, but on the other hand, the light does not
influence the clouds directly in this technique, so it can't simulate the
"glowing" of clouds on the side directed towards the sun.
The nice thing would be, that you don't have to rerender the time intensive
parts (media clouds) when you want to change for example the lens flare/sun
glow.
Christoph
--
Christoph Hormann <chr### [at] gmx de>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/
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Christoph Hormann wrote:
> This technique seems to combine several renderings to a final picture. The
> Povray equivalent would be using the post_process function.
>
> For example: seperate rendering of clouds, sky gradient, sun glow (media), lens
> flare and combining them with post_process.
There's already a "stars" post_process feature that replaces background and
sky_spheres with a starfield (thanks to Chris Huff).
Anyone that would propose a cloud{} statement would certainly be propelled in pov
stardom in no time and for ever, even with the limits you mentioned .
G.
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In article <3992C208.2FF87C6A@inapg.inra.fr>, Gilles Tran
<tra### [at] inapginrafr> wrote:
> I've been to this site countless times but never noticed that this page
> was so detailed :
> http://freespace.virgin.net/hugo.elias/models/m_clouds.htm
> Question for the POV gurus : is it possible to implent this either as a
> macro or directly in the POV code ?
This is basically mapping a perlin noise texture onto a sphere
representing the sky, layering another texture over it to make the sky
and clouds near the sun glow, adding a lens flare, and using fog. You
could use wrinkles, turbulated bozo, or a custom pattern done with
isosurface functions for the cloud pattern.
To animate them, you might try averaging or multiplying several patterns
together(maybe using isosurface functions to get it exactly right), and
translating them in different directions.
--
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/
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In article <3992C97A.959B3E10@inapg.inra.fr>, Gilles Tran
<tra### [at] inapginrafr> wrote:
> There's already a "stars" post_process feature that replaces
> background and sky_spheres with a starfield (thanks to Chris Huff).
That really isn't very useful...it basically randomly colors pixels in
the background areas. It has several weaknesses: the stars don't reflect
or show up behind transparent objects, for example.
> Anyone that would propose a cloud{} statement would certainly be
> propelled in pov stardom in no time and for ever, even with the
> limits you mentioned .
A cloud-specific feature isn't necessary, since this technique should be
quite easy to duplicate in POV.
--
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/
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In article <3992C86A.D9BF3996@schunter.etc.tu-bs.de>,
chr### [at] gmxde wrote:
> This technique seems to combine several renderings to a final
> picture. The Povray equivalent would be using the post_process
> function.
> For example: seperate rendering of clouds, sky gradient, sun glow
> (media), lens flare and combining them with post_process.
Well, this is because it is a real-time program...the analog of the sky
gradient would be fog or media, and the lens flare and sun glow could be
done with layered textures. Actually, all of it should be possible with
layered textures, but it wouldn't look right for other stuff in the
scene.
The perlin noise textures were generated beforehand, but I doubt using
image_maps in POV would save more than a couple seconds of render
time...again, they only used 4 interpolated maps because it is a
real-time program.
> It's definitely worth trying, but on the other hand, the light does not
> influence the clouds directly in this technique, so it can't simulate the
> "glowing" of clouds on the side directed towards the sun.
This is the big flaw of this method...it is only partially 3D, and
doesn't simulate shadows or the effects of the cloud volume.
--
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/
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>For example: seperate rendering of clouds, sky gradient, sun glow
(media), lens
>flare and combining them with post_process.
I was pondering how to do this and the clouds, sky, and sun are easy
enough to do. The only thing left was the lens flare and sun glow, but
notice that in the cloud program the flare and glow vary with the sun
intensity through the clouds. Could post_process read the filter value
of the sun through the clouds and use this to adjust the intensity of
those?
>It's definitely worth trying, but on the other hand, the light does not
>influence the clouds directly in this technique, so it can't simulate
the
>"glowing" of clouds on the side directed towards the sun.
Double sided shading should take care of this. The diffuse highlight
showing from the back side of a large sphere would create the glow.
-Mike
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In article <3992D0E8.24428FA6@aol.com>, Mike <Ama### [at] aolcom>
wrote:
> I was pondering how to do this and the clouds, sky, and sun are easy
> enough to do. The only thing left was the lens flare and sun glow, but
> notice that in the cloud program the flare and glow vary with the sun
> intensity through the clouds. Could post_process read the filter value
> of the sun through the clouds and use this to adjust the intensity of
> those?
I don't think post_process is necessary...unless you are talking about
something completely different from what I am thinking of.
> Double sided shading should take care of this. The diffuse highlight
> showing from the back side of a large sphere would create the glow.
That wouldn't do the effect of thick clouds having dark areas on the
side facing away from the light source. All it would do is make the
parts closer to the sun-spot brighter, which isn't the same.
--
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/
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>I don't think post_process is necessary...unless you are talking about
>something completely different from what I am thinking of.
I think so. Can you think of any other way to have the lens flare and
glow to only dim when the sun is obscured?
You're right about the double_illuminate idea. It was just a thought.
It might work for a lens flare though.
I'm going to start tinkering with this...
-Mike
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In article <3993091C.C9DB4C5B@aol.com>, Mike <Ama### [at] aolcom>
wrote:
> I think so. Can you think of any other way to have the lens flare and
> glow to only dim when the sun is obscured?
Oh, you were talking about the intensity of the flare being linked to
the amount of cloud covering the sun...this would be possible without
post_process, sort of. Use two spheres for the sky: a shadowless blue
one(background won't work properly with the fog) and a partly
transparent cloud sphere. Put the light source outside the blue sphere,
and use media within the inner sphere to get the glare effects. You
might be able to use the same media to get the fog effect.
To get an actual lens flare would be more difficult though...I think you
are right about the best solution being a post_process flare.
--
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/
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