Hi Tracers!

Currently, I'm toying with the idea of visualizing one of those freaky
ideas in "The Hitchhiker's Guide to the Galaxy" - the Magrathean
Workshop of Worlds... I started with an animation of a planet's surface
developing out of a plane by using larger and larger hf_gray_16
renderings of the same bozo pattern, the camera moves toward a defined
point in the planet's lowlands, a few meters above the surface, and then

occurs:

For the starry sky (which during the panoramic turn slowly changes to a
blue daytime desert sky), I used a pigment pattern, and when I change
the camera's look_at point, the stars dance wildly across the scene from
frame to frame, instead of moving slowly out of the view field. Of
course I could instead use an image map, but as my heightfield for the
surface is already VERY big (about 8000 by 6000 pixels) and I only have
256 megs of RAM, I'm quite uneasy about doing this - to look properly,
such a star imagemap should at least be 2000 by 1000, not to mention the
distortions towards the poles.

Is there a way to create a procedural starfield which behaves correctly
when animated?

Why, in general, is no steady movement of the stars possible with
pigment patterns on a sky_sphere?

See you in Khyberspace -
http://www.geocities.com/electricafghan/index-e.html

Yadgar

Post a reply to this message

> Is there a way to create a procedural starfield which behaves
correctly
> when animated?
>
> Why, in general, is no steady movement of the stars possible with
> pigment patterns on a sky_sphere?

You could try Chris Colefax's Galaxy generator, though I don't remember
if it can be animated.

In general, the stars will tend to flicker if they are too small, as
rays hit a star by accident almost, and you see a sample of the much
larger number of stars truly present in the texture.  Moving the camera
causes the rays to fall onto a different set of stars.

The way to do this properly (I think) is to make sure the stars are
about 1 pixel in size, which of course means scaling them differently
for different image sizes.  Either that or use extreme AA settings.

BTW, you probably do have enough memory for a decent image map.

Post a reply to this message

> Is there a way to create a procedural starfield which behaves correctly
> when animated?
>
> Why, in general, is no steady movement of the stars possible with
> pigment patterns on a sky_sphere?


In my opinion, stars with 1 pixel-size look ugly no matter what. And they
don't animate well because of their even smaller size internally in Pov. But
even if you make them move steadily, they will not be suited for an
animation because of the compression codecs. All lossy compression codecs,
such as mpeg, don't like small dots.

Your solution: The stars should be between 2 and 4 pixels each, plus have a
small "glow" around them. I think you can do all this with a procedural
texture: Use a lot of small, randomly placed spheres with a minimum size
(you will need to experiment with it) and of course a maximum size (almost
the same as the minimum). Put them all on the X Y plane (Z=0). Then use the
"object pattern" in Pov3.5 or MegaPov to grap all those spheres into a
pigment. The pigment will have no depth, but this should be perfect, as you
map it spherically on your sky sphere.

You can also achieve the glow effect, by averaging the pigment with up to
255 (20 might be just enough) other pigments that are translated a little
around origin.

Good luck! Let me know if you need more help.  :o)

Regards,
Hugo

Post a reply to this message

On my site (Tutorials->POV-Ray->Tips and Tricks) you can find a procedural
starfield using the crackle-pigment, which should be suitable for animation.

cu!
--
ZK AKA SaD
http://www.povplace.be.tf
"You know what they say: No good deed goes unpunished."

Post a reply to this message

Yadgar <j.b### [at] ndhnet> wrote in news:3C3FE682.739BFCD9@ndh.net:

> Is there a way to create a procedural starfield which behaves correctly
> when animated?

It's probably possible, given enough trial and error, but there's no point 
in going to the trouble as Chris Colefax's galaxy package will create 
animatable starfields with a minimum of effort.

Post a reply to this message