Here is a scene I am trying to render with POV 3.1g for win 98.
No ground fog ever appears. Why? 
// Persistence of Vision Ray Tracer Scene Description File
// File: ?.pov
// Vers: 3.1
// Desc: Basic Scene Example
// Date: mm/dd/yy
// Auth: ?[esp]
//

#version 3.1;

#include "colors.inc"
#include "tex.inc" //contains the texture definition.

global_settings
{
  assumed_gamma 1.4
}
default {texture {pigment {color Red}} }
//#include "fog.inc"
fog { fog_type 2 //Layer: Layer2
    rgb <0.620, 0.000, 0.000>
    fog_offset 6
    fog_alt 0.5 //fade away rate
} //fog


// ----------------------------------------
camera
{
  location  <0.0, 0.5, -4.0>
  direction 1.5*z
  right     4/3*x
  look_at   <0.0, 0.0,  0.0>
}

sky_sphere
{
  pigment
  {
    gradient y
    color_map { [0.0 color blue 0.6] [1.0 color rgb 1] }
  }
}

light_source
{
  0*x // light's position (translated below)
  color red 1.0  green 1.0  blue 1.0  // light's color
  translate <-30, 30, -30>
}

light_source
{
  0*x // light's position (translated below)
  color red 1.0  green 1.0  blue 1.0  // light's color
  translate <30, -30, -30>
}

// ----------------------------------------

//#include "shape.inc" //has preview shape
plane { y, -1 pigment {color rgb <0.7,0.5,0.3>}}

sphere { 0.0, 1 //start of shape
    texture { Texture1 }
} //Sphere


-- 
See my Free stuff page. It compares free website providers, and
lists free internet access providers.
http://www.crosswinds.net/~robertsc/free.htm

Win98 help file loaded with hints and tips, including securing a
Win 95/98 PC in a classroom setting. VB4 help file with lots of
code and hints. 
At http://www.crosswinds.net/~robertsc/

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Put the keyword "hollow" into the sky_sphere.

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In article <39c8cb76@news.povray.org> , "Bob Hughes" 
<per### [at] aolcom?subject=PoV-News:> wrote:

> Put the keyword "hollow" into the sky_sphere.

This is nonsense.  They keyword hollow does not belong in the sky_sphere (in
fact it won't work there at all!).   sky_sphere does not have any volume, it
is infinite - otherwise you would also get the "camera in non-hollow object"
warning!   sky_spheres are explained in the POV-Ray manual.


Now to the problem. Simply add the "distance [value]" to the fog statement,
for example:

fog { fog_type 2 //Layer: Layer2
    rgb <0.620, 0.000, 0.000>
    distance  20
    fog_offset 6
    fog_alt 0.5 //fade away rate
} //fog

This will make the fog very visible.


      Thorsten

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Thank you, that worked. The help file led me to believe that
"distance" was only for type 1 fog. 

Thorsten Froehlich wrote:
> 
> In article <39c8cb76@news.povray.org> , "Bob Hughes"
> <per### [at] aolcom?subject=PoV-News:> wrote:
> 
> Now to the problem. Simply add the "distance [value]" to the fog statement,
> for example:
> 
> fog { fog_type 2 //Layer: Layer2
>     rgb <0.620, 0.000, 0.000>
>     distance  20
>     fog_offset 6
>     fog_alt 0.5 //fade away rate
> } //fog
> 
> This will make the fog very visible.
> 
>       Thorsten

-- 
See my Free stuff page. It compares free website providers, and
lists free internet access providers.
http://www.crosswinds.net/~robertsc/free.htm

Win98 help file loaded with hints and tips, including securing a
Win 95/98 PC in a classroom setting. VB4 help file with lots of
code and hints. 
At http://www.crosswinds.net/~robertsc/

Post a reply to this message

Thank you, that worked. The help file led me to believe that
"distance" was only for type 1 fog. 

Thorsten Froehlich wrote:
> 
> In article <39c8cb76@news.povray.org> , "Bob Hughes"
> <per### [at] aolcom?subject=PoV-News:> wrote:
> 
> Now to the problem. Simply add the "distance [value]" to the fog statement,
> for example:
> 
> fog { fog_type 2 //Layer: Layer2
>     rgb <0.620, 0.000, 0.000>
>     distance  20
>     fog_offset 6
>     fog_alt 0.5 //fade away rate
> } //fog
> 
> This will make the fog very visible.
> 
>       Thorsten

-- 
See my Free stuff page. It compares free website providers, and
lists free internet access providers.
http://www.crosswinds.net/~robertsc/free.htm

Win98 help file loaded with hints and tips, including securing a
Win 95/98 PC in a classroom setting. VB4 help file with lots of
code and hints. 
At http://www.crosswinds.net/~robertsc/

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Just for a try. Does 'inverse' to the plane resolve the problem as well ?

Fabien H

Chuck Roberts a écrit :

> Thank you, that worked. The help file led me to believe that
> "distance" was only for type 1 fog.
>
> Thorsten Froehlich wrote:
> >
> > In article <39c8cb76@news.povray.org> , "Bob Hughes"
> > <per### [at] aolcom?subject=PoV-News:> wrote:
> >
> > Now to the problem. Simply add the "distance [value]" to the fog statement,
> > for example:
> >
> > fog { fog_type 2 //Layer: Layer2
> >     rgb <0.620, 0.000, 0.000>
> >     distance  20
> >     fog_offset 6
> >     fog_alt 0.5 //fade away rate
> > } //fog
> >
> > This will make the fog very visible.
> >
> >       Thorsten
>
> --
> See my Free stuff page. It compares free website providers, and
> lists free internet access providers.
> http://www.crosswinds.net/~robertsc/free.htm
>
> Win98 help file loaded with hints and tips, including securing a
> Win 95/98 PC in a classroom setting. VB4 help file with lots of
> code and hints.
> At http://www.crosswinds.net/~robertsc/

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"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:39c8d2d0$1@news.povray.org...
| In article <39c8cb76@news.povray.org> , "Bob Hughes"
| <per### [at] aolcom?subject=PoV-News:> wrote:
|
| > Put the keyword "hollow" into the sky_sphere.
|
| This is nonsense.  They keyword hollow does not belong in the sky_sphere
(in
| fact it won't work there at all!).   sky_sphere does not have any volume,
it
| is infinite - otherwise you would also get the "camera in non-hollow
object"
| warning!   sky_spheres are explained in the POV-Ray manual.

Curiously the Scene Help doesn't mention that fact in the section The Sky
Sphere or the fog sections either from what I could see there.
I hate to lead people astray like that, sorry.  Glad you corrected me
Thorsten.
I still use sphere instead of sky_sphere so much it's second nature to add
hollow to that anyway.  Guess when I make the mistake and get the error when
putting hollow into one that I don't think twice about it and remove it.

Bob

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"Fabien Hénon" <ffj### [at] club-internetfr> wrote in message
news:39C926BB.1B23DBF2@club-internet.fr...
| Just for a try. Does 'inverse' to the plane resolve the problem as well ?

Shouldn't.  The normal of a plane isn't flipped when the float is negative,
only when the plane normal itself is negative.  Inside and outside of a
plane remains constant otherwise.  Unless I'm wrong about that too.

Bob

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Bob Hughes wrote:

> Curiously the Scene Help doesn't mention that fact in the section The Sky
> Sphere or the fog sections either from what I could see there.

You may be suffering from one of those misconceptions that Warp has
been talking about. A sky_sphere is not a sphere object. It is more
like the background feature that has spherical pigment properties.

-- 
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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Thorsten Froehlich <tho### [at] trfde> wrote:
:> Put the keyword "hollow" into the sky_sphere.

: This is nonsense.  They keyword hollow does not belong in the sky_sphere (in
: fact it won't work there at all!).   sky_sphere does not have any volume, it
: is infinite - otherwise you would also get the "camera in non-hollow object"
: warning!   sky_spheres are explained in the POV-Ray manual.

  Perhaps it could be a good idea to actually TEST the suggestion between
posting it. :)

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Bob Hughes <per### [at] aolcom?subject=pov-news:> wrote:
: I still use sphere instead of sky_sphere so much it's second nature to add
: hollow to that anyway.

  Ever considered using 'inverse' instead?

  If you don't inverse your sky sphere you will be looking at its surface
from the inside and thus the normal vectors will be pointing at the wrong
side producing a possibly unwanted result.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:39c9b0e1@news.povray.org...
| Bob Hughes <per### [at] aolcom?subject=pov-news:> wrote:
| : I still use sphere instead of sky_sphere so much it's second nature to
add
| : hollow to that anyway.
|
|   Ever considered using 'inverse' instead?
|
|   If you don't inverse your sky sphere you will be looking at its surface
| from the inside and thus the normal vectors will be pointing at the wrong
| side producing a possibly unwanted result.

Sage advice, thanks Warp.  I'll certainly try that.

Bob

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:39c9b010@news.povray.org...
| Thorsten Froehlich <tho### [at] trfde> wrote:
| :> Put the keyword "hollow" into the sky_sphere.
|
| : This is nonsense.  They keyword hollow does not belong in the sky_sphere
(in
| : fact it won't work there at all!).   sky_sphere does not have any
volume, it
| : is infinite - otherwise you would also get the "camera in non-hollow
object"
| : warning!   sky_spheres are explained in the POV-Ray manual.
|
|   Perhaps it could be a good idea to actually TEST the suggestion between
| posting it. :)

Yes, well I do when I'm 50% unsure.  I was 99% sure hollow went into
sky_sphere.

Bob

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