This is something that worked in the past, but now it doesn't. It might be 
something obvious and basic, but for some reason I can't find it.

I was doing some space animations and used a sphere with an image map for 
the star background.
Using the usual star textures on the sky sphere made the stars jump too 
much between frames.
So I made a png with a pov file - a star texture on a distant plane and 
used that as a map. 

The image I made was very detailed with a size 1280X960.

This gave stars similar to the sky sphere ones - at least with version 3.1.
Now, the mapped texture that I see is less than 1% of the total image used 
as a map (about the amount of stars that would show on a 50X50 square), 
with the result that it is highly pixelated. I would think that a texture 
mapped onto a sphere would show a much greater percentage (and it did 
before).
With interpolate on, the large and few (square) stars just become a little 
blurry. I have made a bigger map image 2000X2000 and the image is only 
slightly improved. The way this is going, I will only get a similar result 
with a 10,000 pixel square image or larger.

I can't clearly remember whether this is definitely a difference between 
3.1 and 3.5, or it is something I have changed.

The syntax I use is 
---------
sphere
{
  <0, 0, 0>,1
   texture{ pigment {image_map { png "stars.png" map_type 1 
    }
    }  
     
} scale 1000000
 hollow on  } 
--------
I have a camera moving mainly between -70 and 100 from back to front.
Changing the size of the sphere and removing scaling, or changing the scale 
makes no difference.

TIA for any hints.

BTW, the starfield discussion was very interesting, but I was aiming for 
something simpler and quicker.


Helen

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Here's my starfield using an image map...
It works great and animates well.
My "starfld.gif" is 2048x2048 It's a PLASMA image from Fractint
and then using the starfield option.
I think what you may be missing is the "once" keyword...
-============================-
sphere 
    {
    0, 1 hollow
    texture
        { 
        pigment
            { 
            image_map
                { 
                gif "starfld.gif" 
                once 
                map_type 1 
               } // type 1 is spherical
            }
        finish{ ambient 2}
        }
    scale 1e6
    }

-============================-

Emory Stagmer

Helen wrote:
> 
> This is something that worked in the past, but now it doesn't. It might be
> something obvious and basic, but for some reason I can't find it.
> 
> I was doing some space animations and used a sphere with an image map for
> the star background.
> Using the usual star textures on the sky sphere made the stars jump too
> much between frames.
> So I made a png with a pov file - a star texture on a distant plane and
> used that as a map.
> 
> The image I made was very detailed with a size 1280X960.
> 
> This gave stars similar to the sky sphere ones - at least with version 3.1.
> Now, the mapped texture that I see is less than 1% of the total image used
> as a map (about the amount of stars that would show on a 50X50 square),
> with the result that it is highly pixelated. I would think that a texture
> mapped onto a sphere would show a much greater percentage (and it did
> before).
> With interpolate on, the large and few (square) stars just become a little
> blurry. I have made a bigger map image 2000X2000 and the image is only
> slightly improved. The way this is going, I will only get a similar result
> with a 10,000 pixel square image or larger.
> 
> I can't clearly remember whether this is definitely a difference between
> 3.1 and 3.5, or it is something I have changed.
> 
> The syntax I use is
> ---------
> sphere
> {
>   <0, 0, 0>,1
>    texture{ pigment {image_map { png "stars.png" map_type 1
>     }
>     }
> 
> } scale 1000000
>  hollow on  }
> --------
> I have a camera moving mainly between -70 and 100 from back to front.
> Changing the size of the sphere and removing scaling, or changing the scale
> makes no difference.
> 
> TIA for any hints.
> 
> BTW, the starfield discussion was very interesting, but I was aiming for
> something simpler and quicker.
> 
> Helen

Post a reply to this message