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Hi:
I'm having problems with ground fog. My image consists of a sky_sphere and a
plane for the clouds. The floor is in -100*z and the camera is in 0*z being
z the up vector. I would like to have a ground fog over the floor so I do
the following:
fog{
fog_type 2
up <0,0,1>
color rgbt<0,0,0,.5>
fog_offset 1
fog_alt 10
distance 50
translate <0,0,-100>
}
It doesnt work. In fact the fog seems to interact in a very strange way with
the skysphere and the plane!!!
I've read the documentation and I found this statement:
http://www.povray.org/documentation/view/3.6.1/254/
"You should also note that translations do not affect the up direction (and
thus do not affect the fog)."
So can anyone tell me what is happening? How can I translate my fog to a
<0,0,-100> position? Is the problem in the camera? With fog it is needed to
work with
a hollow enviroment? But it is not possible to define a sky_sphere, can
anyone give me some light?
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kike nous apporta ses lumieres en ce 2007/10/03 03:34:
>
>
> Hi:
>
> I'm having problems with ground fog. My image consists of a sky_sphere and a
> plane for the clouds. The floor is in -100*z and the camera is in 0*z being
> z the up vector. I would like to have a ground fog over the floor so I do
> the following:
>
> fog{
> fog_type 2
> up <0,0,1>
> color rgbt<0,0,0,.5>
> fog_offset 1
> fog_alt 10
> distance 50
> translate <0,0,-100>
> }
>
> It doesnt work. In fact the fog seems to interact in a very strange way with
> the skysphere and the plane!!!
>
> I've read the documentation and I found this statement:
> http://www.povray.org/documentation/view/3.6.1/254/
> "You should also note that translations do not affect the up direction (and
> thus do not affect the fog)."
>
> So can anyone tell me what is happening? How can I translate my fog to a
> <0,0,-100> position? Is the problem in the camera? With fog it is needed to
> work with
> a hollow enviroment? But it is not possible to define a sky_sphere, can
> anyone give me some light?
>
>
>
>
>
You use a transmit value in your fog, it's effect can look strange. In this
case, it's why the plane is still visible. The transmit value tel how much of
the background will show trough. A transmit of 0.5 mean that any background will
contribute AT LEAST 50%.
It may be beter to remove the transmit and increast the distance, maybe to 100
to 1000.
The sky_sphere never interact with fog nor media, it's a background pigment that
is returned for any ray that don't encounter any opaque object.
Is your plane deffined as: plane{z, -100} or plane{-z, 100}? In the first case,
you are above the plane, in the second case you are "inside" the plane and the
fog don't extend in that half of the space. Both will show identicaly.
Aparently, using offset 1 translate -100*z, you want the fog to be constant up
to 1 usit from the plane. A beter way is to use offset -99.
If you use this fog:
fog{
fog_type 2
up <0,0,1>
color rgb<0,0,0>
fog_offset -99 // changed from +1
fog_alt 10
distance 200 // up from 50
//removed the translate
}
It will blur the horizon and hide the farthest part of the plane.
The plane I used is: plane{z, -100 pigment{Some_Pigment}}
--
Alain
-------------------------------------------------
Change is inevitable, except from a vending machine.
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