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"Sascha Ledinsky" <sas### [at] users sourceforgenet> schreef in bericht
news:40a33b95@news.povray.org...
> In some cases using one (or more) y planes will produce better looking
clouds
> than a sphere. And it's easy to animate too - you can translate the
texture in
> x/z to simulate wind and in y to make the clouds change their shape...
> -sascha
Or, alternatively, use different nested spheres, but squashed in the
y-direction. You can rotate the spheres too. Condition is that the spheres
be very large (and very squashed). Towards the horizon they look somewhat
better than planes.
Thomas
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In article <40a33b95@news.povray.org>,
Sascha Ledinsky <sas### [at] userssourceforgenet> wrote:
> In some cases using one (or more) y planes will produce better looking clouds
> than a sphere. And it's easy to animate too - you can translate the texture
> in x/z to simulate wind and in y to make the clouds change their shape...
I have never found such a case. Planes will give extremely unrealistic
horizon effects, simply because the horizon is an infinitely distant
flat line. The real world is roughly spherical, and nested spheres model
it much better than stacked planes.
Animation is no harder...you can use exactly the same translations,
because the areas where the difference becomes noticeable are far below
the horizon.
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/
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Christopher James Huff wrote:
> I have never found such a case. Planes will give extremely unrealistic
> horizon effects, simply because the horizon is an infinitely distant
> flat line.
In theory a sphere with a radius of about 6000 km, centered at y = -5999 km
should be the best solution - but then you should use a sphere (the earth)
instead of a ground plane too - and media instead of ground fog - and ...
For clouds I still prefer (layered) planes, and with some ground fog the horizon
looks quite good.
But what I really tried to say is that a large sphere centered near the camera
location gives unrealistic clouds...
-sascha
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> sphere {
> 0, 1000000000
This will create a sphere of clouds centered on the camera, not on the
center of the Earth. That is, the clouds will be extremely unrealistic.
The easiest way of creating more realistic-looking clouds is to use
a plane.
--
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}// - Warp -
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Warp wrote:
|
|>sphere {
|> 0, 1000000000
|
|
| This will create a sphere of clouds centered on the camera, not on the
| center of the Earth. That is, the clouds will be extremely unrealistic.
|
| The easiest way of creating more realistic-looking clouds is to use
| a plane.
|
I wasn't giving a solution for the most realistic clouds, I was
explaining what CFM didn't catch from the tutorial he was following.
Which meant giving a solution to approximate as best as possible the
effect of sky_sphere (which for all intent and purposes is centered
on the camera) with the added benefit of shadow casting clouds.
Jerome
- --
******************************
* Jerome M. Berger *
* mailto:jbe### [at] ifrancecom *
* http://jeberger.free.fr/ *
******************************
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Version: GnuPG v1.2.2 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org
iD8DBQFAo96QqIYJdJhyixIRAl45AJ0R3U3fZ8sJeROXILV9MPHZfAxmrgCcCrN6
76oRVVcA88oKkrlkgwFkZLU=
=NR6E
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> I wasn't giving a solution for the most realistic clouds, I was
> explaining what CFM didn't catch from the tutorial he was following.
> Which meant giving a solution to approximate as best as possible the
> effect of sky_sphere (which for all intent and purposes is centered
> on the camera) with the added benefit of shadow casting clouds.
Do you really think it's a good idea to widespread a simple misconception
without even saying anything about it (eg. something like "note that this
will not give you realistic clouds" etc)?
I wonder why is it so common to put clouds on a giant sphere which is
centered at the camera (or very close to it). Earth clouds certainly
aren't positioned that way. What makes people think they are?
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
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"Warp" <war### [at] tagpovrayorg> schreef in bericht
news:40a3f2e6@news.povray.org...
> I wonder why is it so common to put clouds on a giant sphere which is
> centered at the camera (or very close to it). Earth clouds certainly
> aren't positioned that way. What makes people think they are?
>
The Anthropic Principle, I guess.... ;-}
Thomas
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In article <40a3f2e6@news.povray.org>, Warp <war### [at] tagpovrayorg>
wrote:
> Do you really think it's a good idea to widespread a simple misconception
> without even saying anything about it (eg. something like "note that this
> will not give you realistic clouds" etc)?
I did not see such a note on your suggestion to use planes. ;-)
I still stand by my suggestion: a large sphere for the ground, and one
or more nested spheres for the sky, all centered at the same point far
below the scene. I find the infinite horizon effects very annoying, and
using fog to conceal it often doesn't work very well.
> I wonder why is it so common to put clouds on a giant sphere which is
> centered at the camera (or very close to it). Earth clouds certainly
> aren't positioned that way. What makes people think they are?
The same reason people insisted for ages that the Earth was the center
of the universe.
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/
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Christopher James Huff <cja### [at] earthlinknet> wrote:
> The same reason people insisted for ages that the Earth was the center
> of the universe.
I'm the center of all clouds?-)
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
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> I still stand by my suggestion: a large sphere for the ground, and one
> or more nested spheres for the sky, all centered at the same point far
> below the scene. I find the infinite horizon effects very annoying, and
> using fog to conceal it often doesn't work very well.
I agree, but am not having a lot of success getting this approach working.
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