Hello:

I am using the jslstarfield (below) to generate a space scene background.  The
problem is that whenever I move the camera, or the starfield itself, the
resulting starfield background appears to randomly re-generate with each frame.
 This gives the animation a bizarre appearance (even when I move the camera a
very small distance, say 0.00001*clock).

What can I do to fix this?

#declare jslStarfield =
texture {
  pigment {
    granite
    color_map {
      [0.00 0.76 color Black  color Black]
      [0.80 0.82 color Gray20 color Gray40]
      [0.82 0.84 color Gray40 color Gray60]
      [0.84 0.86 color Gray60 color Gray80]
      [0.86 0.88 color Gray80 color Gray95]
      [0.88 0.91 color Gray95 color White]
      [0.91 1.00 color Black  color Black]
    }
    scale .015
  }
  finish { ambient 1 diffuse 0 }
}

#declare StarSphere = sphere { <0,0,0>, 100000
  inverse
  texture { jslStarfield scale 1  }
}

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james lake nous illumina en ce 2008-06-17 23:30 -->
> Hello:
> 
> I am using the jslstarfield (below) to generate a space scene background.  The
> problem is that whenever I move the camera, or the starfield itself, the
> resulting starfield background appears to randomly re-generate with each frame.
>  This gives the animation a bizarre appearance (even when I move the camera a
> very small distance, say 0.00001*clock).
> 
> What can I do to fix this?
> 
> #declare jslStarfield =
> texture {
>   pigment {
>     granite
>     color_map {
>       [0.00 0.76 color Black  color Black]
>       [0.80 0.82 color Gray20 color Gray40]
>       [0.82 0.84 color Gray40 color Gray60]
>       [0.84 0.86 color Gray60 color Gray80]
>       [0.86 0.88 color Gray80 color Gray95]
>       [0.88 0.91 color Gray95 color White]
>       [0.91 1.00 color Black  color Black]
>     }
>     scale .015
>   }
>   finish { ambient 1 diffuse 0 }
> }
> 
> #declare StarSphere = sphere { <0,0,0>, 100000
>   inverse
>   texture { jslStarfield scale 1  }
> }
> 
> 
The pigment used relies on sub-pixel details to simulate the apearance of a star 
field. An extremely small movement will cause a ray that hit a bright spot to 
completely miss it after the move.
The solution would be to keep the camera stationary and move the rest the scene. 
You can do this by binding the whole scene, exept the camera and the world 
sphere, in an union and apply the translation to the union.
While that will work for translations, it will not for rotations where the 
visible part of the star field change.


-- 
Alain
-------------------------------------------------
EVERYTHING HAS A GENDER

You may not know this but many nonliving things have a gender...

A Hot Air Balloon is Male, because, to get it to go anywhere, you have to light 
a fire under it, and of course, there's the hot air part.

Post a reply to this message

Or: Render the background with a spherical camera and use the rendered image as
a background (with sky_sphere) for the actual animation.

Depending on the resolution of your final animation and the camera angle you're
using the background image should be rendered with a width of approx
2*final_image_width*360/horizontal_viewing_angle in order to prevent both
blurry appearance (resolution too low) and flickering (resolution to high).

Hope that helps!

Regards Roman



Alain <ele### [at] netscapenet> wrote:
> james lake nous illumina en ce 2008-06-17 23:30 -->
> > Hello:
> >
> > I am using the jslstarfield (below) to generate a space scene background.  The
> > problem is that whenever I move the camera, or the starfield itself, the
> > resulting starfield background appears to randomly re-generate with each frame.
> >  This gives the animation a bizarre appearance (even when I move the camera a
> > very small distance, say 0.00001*clock).
> >
> > What can I do to fix this?
> >
> > #declare jslStarfield =
> > texture {
> >   pigment {
> >     granite
> >     color_map {
> >       [0.00 0.76 color Black  color Black]
> >       [0.80 0.82 color Gray20 color Gray40]
> >       [0.82 0.84 color Gray40 color Gray60]
> >       [0.84 0.86 color Gray60 color Gray80]
> >       [0.86 0.88 color Gray80 color Gray95]
> >       [0.88 0.91 color Gray95 color White]
> >       [0.91 1.00 color Black  color Black]
> >     }
> >     scale .015
> >   }
> >   finish { ambient 1 diffuse 0 }
> > }
> >
> > #declare StarSphere = sphere { <0,0,0>, 100000
> >   inverse
> >   texture { jslStarfield scale 1  }
> > }
> >
> >
> The pigment used relies on sub-pixel details to simulate the apearance of a star
> field. An extremely small movement will cause a ray that hit a bright spot to
> completely miss it after the move.
> The solution would be to keep the camera stationary and move the rest the scene.
> You can do this by binding the whole scene, exept the camera and the world
> sphere, in an union and apply the translation to the union.
> While that will work for translations, it will not for rotations where the
> visible part of the star field change.
>
>
> --
> Alain
> -------------------------------------------------
> EVERYTHING HAS A GENDER
>
> You may not know this but many nonliving things have a gender...
>
> A Hot Air Balloon is Male, because, to get it to go anywhere, you have to light
> a fire under it, and of course, there's the hot air part.

Post a reply to this message