 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Hi, I'm experimenting on POV-Ray trying to make a realistic Earth-like sky
using scattering media and need help finding a place to start. I haven't
found any good tutorials on how to accomplish this, and my own attempts
always seem to make the atmosphere look too dark or too bright.
Also, I'm trying to use realistic proportions for the Sun in my scene,
placing it at a distance of about 1 AU (1.5e11 m) from the observer and
using a sphere of radius 7.0e8 m. However, the sphere isn't visible in my
scene when I do this, even when I scale the units to 1.5e4 and 7.0
respectively. Is the Sun really that small in the sky, or am I doing
something wrong?
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
mtxcoll <mtx### [at] gmail com> wrote:
> Also, I'm trying to use realistic proportions for the Sun in my scene,
> placing it at a distance of about 1 AU (1.5e11 m) from the observer and
> using a sphere of radius 7.0e8 m.
There's no advantage in doing that compared to putting it closer and
making it smaller.
> However, the sphere isn't visible in my
> scene when I do this
It's possible that POV-Ray is just not rendering it because it's too
far away. POV-Ray uses a limit value for how far objects can be for them
to be taken into account.
--
- Warp
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
mtxcoll nous apporta ses lumieres en ce 2007/08/13 16:16:
> Hi, I'm experimenting on POV-Ray trying to make a realistic Earth-like sky
> using scattering media and need help finding a place to start. I haven't
> found any good tutorials on how to accomplish this, and my own attempts
> always seem to make the atmosphere look too dark or too bright.
There is no absolute settings. You need to adjust your media acording to your
scene. Try adjusting the color value by small steps. Try using another
scattering model until you are satisfied.
>
> Also, I'm trying to use realistic proportions for the Sun in my scene,
> placing it at a distance of about 1 AU (1.5e11 m) from the observer and
> using a sphere of radius 7.0e8 m. However, the sphere isn't visible in my
> scene when I do this, even when I scale the units to 1.5e4 and 7.0
> respectively. Is the Sun really that small in the sky, or am I doing
> something wrong?
>
>
You have to large scale variations.
If using a 1 meter = 1POV unit scale, and your objects scale down to about 1mm,
you have a scale range of 1 500 000 000 000 to 0.001! You just can't have such a
range with any kind of acuracy using floating point values.
The best you can do is to fake the huge proportions of the solar system. Make
your sun about 1 000 000 000 times closer and smaller. Scale down any area_light
array extent by the same amount. Add parallel to that light to beter simulate an
extremely distant light source.
You may have to adlust the positioning, the down scaling may make your sun drift
away from the visible area of your scene.
--
Alain
-------------------------------------------------
Keep your eyes wide open before marriage, half shut afterwards.
Benjamin Franklin
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"mtxcoll" <mtx### [at] gmailcom> wrote:
> Hi, I'm experimenting on POV-Ray trying to make a realistic Earth-like sky
> using scattering media and need help finding a place to start. I haven't
> found any good tutorials on how to accomplish this, and my own attempts
> always seem to make the atmosphere look too dark or too bright.
>
might be helpful
http://runevision.com/3d/povgoodies/
Hildur
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Hildur K." <hil### [at] 3dcafemailevery1net> wrote:
> "mtxcoll" <mtx### [at] gmailcom> wrote:
> > Hi, I'm experimenting on POV-Ray trying to make a realistic Earth-like sky
> > using scattering media and need help finding a place to start. I haven't
> > found any good tutorials on how to accomplish this, and my own attempts
> > always seem to make the atmosphere look too dark or too bright.
> >
>
> might be helpful
>
> http://runevision.com/3d/povgoodies/
>
> Hildur
Thanks! This is pretty useful as a guide for how my atmosphere should look
like. I was still hoping to use just media to create a sky, though, just
to see how it could be done. I've hit a major hiccup though: even though I
can get a consistently blue sky using Rayleigh scattering, when I try
combining it with Mie murky scattering the sun's glare is enormous and I
don't know how to reduce it. If I reduce the amount of light or density of
the atmosphere too much I end up with a black sky. Here's my scene file so
far:
camera {
location <-4, 0, 0>
look_at <0, 0, 0>
rotate y*0
}
light_source {
<1000, 0, 0>
rgb 3
looks_like {
sphere {
<0,0,0>, 10
pigment { color White }
finish { ambient 1 }
}
}
parallel
point_at <0, 0, 0>
rotate z*14
}
plane {
y, -1
pigment { color White }
}
sphere {
<0,0,0>, 300
pigment { transmit 1 }
hollow
interior {
media { // Rayleigh scattering
scattering {4, <50,128,194>/255*0.5}
density { rgb 0.005 }
}
media { // Mie Murky scattering
scattering {3, 1e-9}
density {rgb 1e-9}
}
}
}
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Not sure if this is related but ATM thickness of 300 and sun
distance of 1000 seem a bit mismatched, although of course
you can't use the real numbers due to scaling problems.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
mtxcoll nous apporta ses lumieres en ce 2007/08/14 16:14:
> "Hildur K." <hil### [at] 3dcafemailevery1net> wrote:
>> "mtxcoll" <mtx### [at] gmailcom> wrote:
>>> Hi, I'm experimenting on POV-Ray trying to make a realistic Earth-like sky
>>> using scattering media and need help finding a place to start. I haven't
>>> found any good tutorials on how to accomplish this, and my own attempts
>>> always seem to make the atmosphere look too dark or too bright.
>>>
>> Have you looked into Rune´s Fast Sky?
>> might be helpful
>>
>> http://runevision.com/3d/povgoodies/
>>
>> Hildur
>
> Thanks! This is pretty useful as a guide for how my atmosphere should look
> like. I was still hoping to use just media to create a sky, though, just
> to see how it could be done. I've hit a major hiccup though: even though I
> can get a consistently blue sky using Rayleigh scattering, when I try
> combining it with Mie murky scattering the sun's glare is enormous and I
> don't know how to reduce it. If I reduce the amount of light or density of
> the atmosphere too much I end up with a black sky. Here's my scene file so
> far:
>
> camera {
> location <-4, 0, 0>
> look_at <0, 0, 0>
> rotate y*0
> }
>
> light_source {
> <1000, 0, 0>
> rgb 3
> looks_like {
> sphere {
> <0,0,0>, 10
> pigment { color White }
> finish { ambient 1 }
> }
> }
> parallel
> point_at <0, 0, 0>
> rotate z*14
> }
>
> plane {
> y, -1
> pigment { color White }
> }
>
> sphere {
> <0,0,0>, 300
> pigment { transmit 1 }
> hollow
> interior {
> media { // Rayleigh scattering
> scattering {4, <50,128,194>/255*0.5}
> density { rgb 0.005 }
> }
> media { // Mie Murky scattering
> scattering {3, 1e-9}
> density {rgb 1e-9}
> }
> }
> }
>
>
Try lowering only the second media's density.
Apply a density modifier like spherical. Scale the spherical pattern by less
than 300, something around 180 to 260 could be an acceptable radius. Play around
with color_maps and scaling to modulate it's density.
Try using 2 containers, one for the raleigh model scattering, a second, smaller
one, for the mie murky model.
You can also experiment with mode 5 "Henyey-Greenstein" with an exentricity from
0.75 to 0.97. Higher values make the scattering more directional, tightening the
hallow effect around the "Sun".
--
Alain
-------------------------------------------------
You know you've been raytracing too long when you know the teapot bezier patches
by heart.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Christian Froeschlin <chr### [at] chrfrde> wrote:
> Not sure if this is related but ATM thickness of 300 and sun
> distance of 1000 seem a bit mismatched, although of course
> you can't use the real numbers due to scaling problems.
You're probably right; the only problem with reducing the size of the
bounding sphere further is that it becomes obvious and clashes with the
real horizon.
I've noticed that, when used together, the effect of the Mie scattering
media depends largely on the density of the Rayleigh media. After a certain
point, reducing the density of the former has no effect on the scene. For
now, I've replaced the media with following code:
sphere {
<0,0,0>, 1
pigment { transmit 1 }
hollow
interior {
media { // Rayleigh scattering
scattering {4, <50,128,194>/255*0.5}
density { rgb 0.05 }
}
}
translate z*0.5
}
sphere {
<0,0,0>, 1
pigment { transmit 1 }
hollow
interior {
media { // Mie murky scattering
scattering {3, 0.05}
density {rgb 0.05}
}
}
translate z*-0.5
}
and I've been playing around with the values. I can reduce the intensity of
the glare in the intersection of these two spheres, but not the size.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|
